Keywords
► mobile platforms
► quantified self
► chronic illness or
special needs
► electronic health
records and systems
► personal health
records
► smart phone
Abstract
Background Self-tracking through mobile health technology can augment the
electronic health record (EHR) as an additional data source by providing direct patient
input. This can be particularly useful in the context of enigmatic diseases and further
promote patient engagement.
Objectives
This study aimed to investigate the additional information that can be
gained through direct patient input on poorly understood diseases, beyond what is
already documented in the EHR.
Methods
This was an observational study including two samples with a clinically
confirmed endometriosis diagnosis. We analyzed data from 6,925 women with
endometriosis using a research app for tracking endometriosis to assess prevalence
of self-reported pain problems, between- a nd within-person variability in pain over
time, endometriosis-affected tasks of daily function, and self-management strategies.
We analyzed data from 4,389 patients identi fied through a large metropolitan hospital
EHR to compare pain problems with the self-tracking app and to identify unique data
elements that can be contributed via patient self-tracking.
Results
Pelvic pain was the most prevalent problem in the self-tracking sample
(57.3%), followed by gastrointestinal-r elated (55.9%) and lower back (49.2%) pain.
Unique problems that were captured by self-tracking included pain in ovaries (43.7%)
and uterus (37.2%). Pain ex perience was highly variable both across and within
participants over time. Within-person vari ation accounted for 58% of the total variance
in pain scores, and was large in magnitude, based on the ratio of within- to between-
person variability (0.92) and the intraclass correlation (0.42). Work was the most
affected daily function task (49%), and there was signi ficant within- and between-
person variability in self-management effectiveness. Prevalence rates in the EHR were
significantly lower, with abdominal pain being the most prevalent (36.5%).
Conclusion
For enigmatic diseases, patient self-tracking as an additional data source
complementary to EHR can enable learning from the patient to more accurately and
comprehensively evaluate patient health history and status.
received
May 17, 2020
accepted
July 14, 2020
DOI https://doi.org/
10.1055/s-0040-1718755.
ISSN 1869-0327.
© 2020 Georg Thieme Verlag KG
Stuttgart · New York
THIEME
Research Article 769
Article published online: 2020-11-18
Background
and Signi ficance
The Learning Health System (LHS) framework proposes an
improved health care system to accelerate the lengthy ( /C24 17
years) learning health cycle from health care data to research
findings that inform clinical decisions by learning and shar-
ing information from patients, care delivery systems, and
clinical research over time.
1,2 This framework relies on the
electronic health record (EHR) as a primary source for gain-
ing information about patients and generating evidence to
inform care,3 and aims to make the research-to-clinical care
pipeline more ef ficient4 through use of big data, health
technologies, and participatory design. 5,6
The EHR constitutes a rich, convenient source of data for
clinical decision-making, 7 conducting biomedical re-
search,8,9 and generating relevant and actionable knowledge
that can inform the tailoring of treatments. 10 The problem
lists within the EHR are particularly useful as they provide a
structured, comprehensive, and accessible list of patient
problems.11 Problem lists include diagnoses, illnesses, inju-
ries, and other factors that affect the health of the patient,
documented by the provider at the point of care and stored in
standard encoding systems. 12 They facilitate data sharing,
information retrieval, and communication throughout the
health care continuum, and further provide data source for
research studies and other secondary data uses. 12
Yet, sole reliance on the EHR and data collected at point of
care can be insuf ficient,13 particularly when studying condi-
tions that lack adequate documentation, 14 conditions that
have a fluctuating course over time, and in instances where
the clinic assessment of an outcome might differ from its
ambulatory assessment.15 Health providers may not log diag-
nosis codes for observed conditions that do not require treat-
ment, diagnostic testing, or referral.8 Previous studies further
report incompleteness and signi ficant variability in provider
agreement on problem lists,16 and significant burnout due to
EHR use among providers17–19 resulting in less time-treating
patients, incomplete chart notes, and duplicate records. 17
These factors can collectively contribute to de ficiencies in
EHR data accuracy, quality, and level of detail. 20 This can
subsequently pose challenges for not only clinical care, 21 but
also research including disease case identi fication14,22 and
longitudinal analyses.20 In the context of enigmatic diseases,
these de ficiencies can further challenge attempts to under-
stand and describe (i.e., “characterize”) the disease, derive
accurate and comprehensive evaluations of patient ’ s disease
status and subsequently target their needs.
One approach to circumvent these limitations is to aug-
ment the EHR data with direct patient input obtained
through self-tracking.
23–25 Self-tracking is de fined as the
practice of repeatedly collecting data and re flecting on it
to acquire knowledge or achieve a goal such as behavior
change.
26–29 Since these data capture patients ’ day-to-day
experiences outside of formal clinical settings, 28,30 they can
aid in differential diagnosis 31 and monitoring of disease by
providing additional information not obtained from the EHR.
In addition to contributing to better patient care and shared
clinical decision-making, 24,32–34 including the patient in the
data generation and sharing process further circumvents
placing additional documentation burden on the provider
at point of care. As such, this approach could be an attractive
alternative to efforts to increase provider EHR documenta-
tion responsibility.
35 The potential impact of self-tracked
health data through mHealth technology for informing evi-
dence-based care is acknowledged by many, 36,37 including
the World Health Organization (WHO) stating that it can help
address the growing burden of chronic disease.
38 These
factors collectively provide impetus for investigating the
data elements that can be elicited from mobile patient
tracking data for describing enigmatic diseases.
One such enigmatic condition is endometriosis: a systemic,
estrogen-dependent inflammatory condition with a range of
debilitating symptoms,
39 comorbidities,40 and associated with
significant impact on daily function and quality of life
(QoL).41,42 Chronic pelvic pain is its most frequent symptom43;
others include pain with sexual intercourse (dyspareunia),
painful urination (dysuria), and ovulation pain. 44,45 Endome-
triosis is associated with a productivity loss of 6.3 hours/week46
and an estimated $69.4 billion per year in excess health
expenditures in the United States,42 and is the second leading
indication for hysterectomy.47 Despite its prevalence rate of 10%
among women of reproductive age, 44 endometriosis is an
underfunded disease48 that is still considered “clinically con-
fusing” and “surprising,”44,49 with no cure or adequate treat-
ment to date. There further is substantial between-patient
variation in its clinical manifestations, 44,49 which likely con-
tributes to the approximately 6.7 ( /C6 6.3) year delay between
symptom-onset and its surgical diagnosis,50 and the difficulty
of understanding its heterogeneous pathophysiology and iden-
tification of possible subtypes (i.e.,“phenotypes”)o ft h ed i s e a s e .
As a disease demographic, endometriosis patients further
face inequities with respect to access to clinical care, 40,51
including inadequate insurance coverage of endometriosis-
related treatments,
40,52 and gender bias and attitudes in flu-
encing physician ’ s diagnostic and treatment decisions, 53,54
which could be contributing to the underdocumentation of
the patient ’ s disease experience. An investigation 55 of the
patterns of prevalence, incidence, and frequency of endome-
triosis reported that no data are available across the past
30 years to attempt to document changes in presenting
symptom severity, life impact, or short- or long-term prog-
nosis among women with endometriosis. Failure to obtain
the right data about these patients is a missed opportunity
for effectively targeting their unique needs,
56 and we pro-
pose that this lack of proper documentation can be augment-
ed through patient self-report. Improving documentation
can provide the foundation to address the inequities in
diagnosis and care for those with endometriosis and that
including the patient in the generation of such documenta-
tion can be a starting point in this endeavor.
Our inquiry is in line with the goal of LHS to create patient-
centered care systems and is further supported by previous
recommendations
57 for leveraging health information tech-
nologies to support and implement this goal. It is proposed
that patient-centered information technologies can be lever-
aged to democratize the health care system within the LHS
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.770
through patient engagement and inclusion in knowledge co-
creation. As such, our study addresses a timely question by
exploring the potential of patient self-tracking for augment-
ing the currently relied upon clinical data sources.
Objectives
Using endometriosis as a grounding example, we investigate
the additional information that can be gained through mHealth
self-tracking on conditions that are poorly understood and
documented. Accordingly, this study aims to (1) describe
endometriosis pain problems documented through self-track-
ing and in the EHR to investigate the potential of self-tracking
for augmenting the EHR documentation, (2) quantify the
between- and within-personfluctuations in pain to character-
ize the dynamic nature of endometriosis, and (3) asses endo-
metriosis impact on daily function and its self-management
documented through self-tracking as additional data elements
that can provide information about the burden of disease and
possible points of intervention for disease management.
42,43
Methods
Study design and protocols were approved by the Columbia
University Irving Medical Center (CUIMC) Institutional Review
Board (AAAQ9812). This was a retrospective study conducted
with data from two independent samples of women with a
clinician or surgery confirmed diagnosis of endometriosis.
Self-Tracking Sample
We obtained self-tracking data from Phendo, an observational
research app for tracking endometriosis symptoms and avail-
able for iOS
1 and Android. 2 Phendo allows anyone with
endometriosis around the world to download the app at any
time to characterize their endometriosis experience by track-
ing symptoms, activities, and self-management techniques.
Users are free to track as much or as sporadically as they wish,
and they do not receive any prompts or requests to track a
specific variable from the research team. Endometriosis diag-
nosis is determined through self-report based on participants’
response to a question asking whether the participant has
endometriosis and if so, how it was diagnosed (i.e., surgery or
clinician confirmation). Phendo was designed using a partici-
patory design approach through a series of qualitative and
quantitative studies with endometriosis patients, with the
goal of creating a patient-centered tool that engages the user
as an active participant in the research on better understand-
ing endometriosis.
58–60 As such, users of Phendo self-track as a
form of participatory research to contribute to creation of
better documentation of the patient disease experience.
Aligned with goals of the LHS for promoting patient engage-
ment,
6,61 these aspects of Phendo make it particularly suitable
for undertaking this investigation.
Electronic Health Record Cohort Extraction
The Observational Health Data Sciences and Informatics
(OHDSI) de-identi fied instance of the CUIMC Data Ware-
house62,63 was queried to select a cohort of endometriosis
cases for description of pain problems documented in the
EHR. The CUIMC EHR system is used across the medical
center university hospitals, clinics, and doctors’ offices across
the City of New York, which has a population of approxi-
mately 8.44 million, including 43% White, 24% Black, 14%
Asian, 15% other race, and 3.5% two or more races.
64 The
clinical data warehouse includes both inpatient and outpa-
tient records and contains 36,578 “concepts” (i.e., clinical
entities such as findings, diagnoses, drugs, and procedures)
including 11,952 conditions, 12,334 drugs, and 10,816 pro-
cedures from 5,364,781 patients. 65
We extracted the data using the OHDSI Observational
Medical Outcomes Partnership (OMOP) Common Data Model
(CDM)62,66,67 and SNOMED CT as the standardized EHR
vocabulary.68 The CDM formally speci fies the encoding and
relationships among EHR concepts in a consistent and stan-
dardized way using a hierarchy of subtypes. 62,68 This har-
monizes disparate coding systems with minimal information
loss to a standardized vocabulary by mapping source con-
cepts from different systems (e.g., ICD-9, ICD-10, RxNorm,
CPT4, NDC, etc.) onto a standard concept ID during the
extract-transform-load (ETL) process. SNOMED CT is the
designated U.S. standard terminology for EHR diagnosis
and problem lists, and has distinct advantages over ICD
codes for capturing discrete patient care diagnoses.
69,70 It
hierarchically organizes concepts, which allows aggregation
of information based on subtype classi fication. More specific
(i.e., descendent or child) concepts have more granularity
and detail, whereas more general (i.e., ascendent or parent)
concepts have less granularity and clinical detail, but they
aggregate similar subtype concepts (e.g., “abdominal tender-
ness of left lower quadrant” and “right lower quadrant pain”)
into logical groups (e.g., “abdominal pain ”) which can be a
desirable feature when conducting statistical analyses.
Electronic Health Record Sample
A cohort of women with endometriosis in the EHR was
created using the following set of criteria that have previ-
ously been demonstrated 71 to have a speci ficity of 93% and
precision of 85% for correctly selecting endometriosis
patients in the EHR: women 15 to 49 years old with an
endometriosis-related or endometriosis-prevalent proce-
dure, an endometriosis concept code 30 days prior or post
either of these procedures and documentation of an endo-
metriosis concept code after the initial procedure. For endo-
metriosis condition codes, we used the SNOMED concepts
“endometriosis” (129103003), “endometriosis of the ovary ”
(266589005), “endometriosis of the pelvic peritoneum ”
(198251001), and “endometriosis of the uterus ” (76376003).
Outcomes
Self-Tracked Pain Problems
The Phendo app includes four pain-related questions
(►Table 1 ). Item “Where is the pain? ” allows users to select
responses (e.g., “cervix,”“ vagina,” and “chest”) using a visual
pain scale ( ►Supplementary Figure S1 , available in the
online version), similar to the McGill Pain Questionnaire. 72
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 771
Item “any gastrointestinal/urine symptoms? ” allows partic -
ipants to report painful bowel movements (i.e., dyschezia),
dysuria, and epigastric (e.g., gas) pain.
Pain Problems in the Electronic Health Record
We selected all pain-related problems documented in the
patients’ records and computed their prevalence rates to
describe documentation of endometriosis-related pain in the
EHR. We chose to investigate the problem lists in the EHR due
to their relevance for both research and clinical practice.
Problem lists provide a structured, systematic way to contain
clinician notes, facilitating access to data and conducting
research.
11 From a clinical standpoint, they improve efficien-
cy for multiple providers to coordinate patient management,
and for those who are taking care of new patients to
familiarize themselves with a patient ’ s problems quickly. 73
Pain Variability
Investigations of within- and between-individual variability
in endometriosis pain were conducted using self-tracked
data from Phendo participants. While signi ficant pain vari-
ability has previously been reported in other conditions,
74
between- versus within-individual variability in pain over
time in endometriosis has not been quanti fied. We under-
took this investigation because disease course over time and
across patients can have important implications for deriving
comprehensive profiles of patient disease history and status,
identification of disease phenotypes,
74 and for predicting
change in disease course or functional capacity over time. 75
To jointly assess variability for both dimensions of area
and severity of pain, we created a composite day-level pain
score by adding the severity scores reported for each body
area (e.g., moderate pain in abdomen, mild pains in chest and
leg would yield 2 þ 1 þ 1 ¼ 4 as the total score), removing any
problem-severity duplicate for the day. Removing day-level
duplicates for pain area-severity pairs circumvents several
issues: (1) the possibility of rumination/catastrophizing,
which might look like, for example, a participant tracking
the same intensity of pain in the same area multiple times
within a span of several hours, (2) to account for the day-level
tracking habits of the participants (e.g., some participants
might track a pain area once at the end of the day even if they
experience it multiple times during the day), and (3) any
possible errors during data transfer from the app to the data
warehouse (e.g., if there is no reception or wi- fi at the time of
tracking, there might be a delay in data dumping, potentially
though infrequently leading to duplicates of the entry into
the data warehouse).
Additional Data Elements
Prevalence of affected daily function tasks and self-manage-
ment techniques were assessed for the Phendo sample.
Participants can track free-text responses to these two items,
which then get mapped onto common terms for standardi-
zation (e.g., “go to a family gathering, ”“ hang out with
friends” get mapped onto “socialize”). This standardization
process has been used in other previous research from our
group,71,76 which we maintain for this analysis, and rely on
published literature 43,52 for generalizability and compara-
bility of the prevalence estimates.
Data Analytic Approach
Prevalence of Pain Problems
In Phendo, we computed total counts and percentages of pain
problems across the entire sample by including the total
sample size in the denominator instead of limiting to the
number of participants to those who ever tracked a pain
problem, as a more conservative approach. In the EHR
sample, we computed counts and percentages of pain prob-
lems, aggregating at the ascendent concept level, as this
allows for logical groupings of pain problems.
For pain problems that exist in both samples, we con-
ducted two-sample tests for equality of proportions.
77 We
further computed the standardized z scores and the con fi-
dence intervals around the difference between the two
Table 1 Phendo pain-related variables and tracking statistics ( n ¼ 6,925)
Question Sample
size
Tracked instances
(median/mean/SD/range)
Tracking frequency in
days (mean/SD/range)
Where is the pain?
How severe is the pain? a
5,205 42/105.5/162.5/1 –965 6.3/26.4/1 –1,147
Any other pain symptoms? b
How severe is the symptom? a
4,413 25/66.6/103.8/1 –536 8.2/30.7/1 –1,147
Any gastrointestinal/urine issues?
How severe is the symptom? b
4,578 30/71.9/106.8/1 –573 7.4/29.1/1 –1,147
How was sex? (dyspareunia) 676 50/85.0/87.5/1 –344 4.7/19.7/1 –609
Which activities are hard to do? 5,764 36/96.5/142.1/1 –708 5.5/28.2/1 –999
What did you do to self-manage?
Did it help? ( “helpful ” or “not helpful/no effect ”)
6,025 40/106.0/164.9/1 –958 5.3/27.4/1 –1,019
Abbreviation: SD, standard deviation.
aSeverity of the pain is tracked as “mild” (1), “moderate ” (2), and “severe” (3).
bResponses to item “any other pain symptoms? ” were included to capture pain reports in instances where a participant might have tracked this item
but not item 1 or 3.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.772
proportions.78 We a priori chose to compute prevalence rates
based on the aggregate parent concepts due to reasons
related to the EHR data architecture described earlier (See
Electronic Health Record Cohort Extraction ).
Variability of Pain
To describe the distribution of severity levels across pain
problems at the sample level, we computed frequencies of
three severity levels for each body area (i.e., each pain
location-severity combination is summed and divided by
the participant’ s total counts of tracks to account for tracking
frequency). To quantify pain variability, we first computed
the ratio of within-person to between-person variability
75
(i.e., average within-person standard deviation (SD) divided
by the SD of the overall mean of all the participant-level
mean scores). This ratio provides a standardized expression
of the temporal variability relative to the distribution of the
sample scores.
75 This is analogous to computing an effect size
(e.g., Cohen’ s d or a t-score) where the magnitude of effect is
expressed in SDs, and provides two advantages that make it
particularly suitable when there is both substantial average
within- and between-person variability in the data. First,
because change is expressed as a standardized score, change
and its statistical signi ficance can be evaluated for an indi-
vidual without referring to scores from other individuals.
Second, it incorporates between-person differences in mag-
nitude of variability by adjusting the change in terms of each
individual’ s magnitude of variability.
75
Next, we estimated the between- and within-person var-
iances using a linear mixed-effects model (LMM) where day-
level pain was regressed on the grouping variable of partici-
pant as a random effect. LMMs are commonly used in repeated
measures designs and provide estimates of variance in the
outcome (i.e., pain) explained by the predictor variables (i.e.,
participant).
79 The predictor term for participant in the model
is included as a random effect, which handles nonindepen-
dence in the data and estimates a separate intercept for each
participant. This provides an estimate of the between-partici-
pant variance, that is, variation in pain explained by the
“grouping structure” where, group here refers to each partici-
pant. In this type of model where the only predictor is the
participant variable and the intercept, the total variance is
assumed to equal to the sum of between-participant and
within-participant (i.e., the residual) variances. Using these
estimates, we computed the intraclass correlation (ICC), which
is calculated as the variance among participant means over the
sum of participant-level and data-level (residual) variances.
80
The ICC (also referred to as “repeatability”) is a common and
recommended measure for assessing stability or fluctuation
over time, and represents the fraction of the total variance in
the population of interest that can be attributed to variation
among groups. 80 It further provides an estimation of the
expected correlation between two randomly drawn units
that are in the same group81 (e.g., two repeated measurements
of pain for one individual). Larger ICC values indicate larger
within-group correlation or repeatability and larger magni-
tude of the variance explained by the between-group varia-
tion. Finally, we estimated the confidence intervals for the ICC
using parametric bootstrapping and the statistical significance
of the ICC in the LMM using a likelihood ratio test (LRT).
80,82
The LRT assesses goodness-of-fit between two competing (e.g.,
null and alternative) models by comparing their log
likelihoods.
Additional Data Elements
Using the Phendo sample, we computed prevalence rates for
daily function tasks, self-management techniques, and fre-
quency of effectiveness (and its SD) of each self-management
technique.
Results
Sample Characteristics
Phendo sample characteristics are provided in ►Table 2 .
There were 6,925 participants with a surgical- or clinician-
confirmed diagnosis of endometriosis who responded to at
least one of the questions pertaining to pain, daily function
tasks, or self-management techniques. The EHR query iden-
tified 4,389 endometriosis patients, which translates to a
prevalence of 0.4% documented endometriosis cases (i.e., out
of 1,097,250 females in the same age bracket documented
within the same time frame) in the clinical database. The
sample consisted of women aged 14 to 49, with a mean age of
36.4 (SD ¼ 7.4) and median age of 37 (mean absolute devia-
tion ¼ 7.4). With respect to race, 1,227 (56.0%) were white,
431 (9.8%) were Black/African-American, 202 (4.6%) were
Asian, 18 (0.4%) were other Paci fic -Islander, 23 (0.5%) were
Asian Indian, 3 (0.06%) were American Indian or Alaska
Native, 20 (0.4%) were of other race, and 2,462 (56.0%) did
not have race data. Ethnicity data were unavailable on more
than half the patients; 651 (14.8%) were Hispanic, 1,420
(32.3%) were non-Hispanic, and no data were available from
2,318 patients. We further searched for data on other demo-
graphic factors (e.g., such as employment and education
status); however, no further information was available.
Outcomes
D e s c r i p t i o no fP a i nP r o b l e m si nP h e n d o
A visual depiction of the prevalence of pain problems in Phendo
are provided in ►Figure 1 . Pelvic pain was the most prevalent
problem (57.3%), followed by lower back pain (49.2%) and
ovarian pain (43.7%). Gastrointestinal (i.e., epigastric and in-
testinal) problems collectively were prevalent in 55.9% of the
sample, comparable to that of pelvic pain. Unique pain prob-
lems identified through self-tracking included pain in ovaries,
uterus, vagina, cervix, dyschezia, dyspareunia, and rectal pain
(
►Supplementary Table S1 , available in the online version).
D e s c r i p t i o no fP a i nP r o b l e m si nt h eE l e c t r o n i cH e a l t h
Record
Pain problem counts and prevalence rates in the EHR sample
are provided in ►Supplementary Table S2 (available in the
online version). We identi fied 19 parent pain concepts and
101 unique descendent concepts mapped onto one or more
parent concepts. Abdominal pain was the most prevalent
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 773
pain problem (36.5%), followed by pain in pelvis (29.8%). Rest
of the pain problems were documented for less than 10% of
the patients, including chest pain (9%), dysuria (4.3%), and
backache (6.8%). Of note, 856 pelvic pain concepts were also
mapped under “abdominal pain,” which included dysmenor-
rhea, renal colic, and bladder pain. Excluding these repeated
cases, there were 1,147 unique “abdominal pain ” concepts
documented in the EHR sample (26.1%). Upon further in-
spection, we identi fied 101 instances of breast pain under
the “chest pain” concept (2.3%), and 128 instances of epigas-
tric pain under “abdominal pain ” (2.9%).
Two Samples Proportion Tests
Results
from the two-sample proportion tests are provided
in ►Table 3 . All pain problems were signi ficantly more
prevalent in the Phendo sample ( p ¼ 0.01 for abdominal
pain, p < 0.001 for all others). Largest differences in propor-
tions were observed for back pain, headache/migraines, and
pelvic pain ( ►Table 3 ).
Variability in Pain
Qualitative Description of Variability
Visualization of self-tracked pain reports at different levels of
severity and through time indicated large variability in the
average intensities reported across participants ( ►Figures 2
and 3). Moderate pain was the most prevalent severity across
body areas (►Figure 2 top), in line with previous literature on
pain typology in endometriosis.45 However, tracking frequen-
cies of all three severity levels signi ficantly varied for all pain
problems based on the SDs ( ►Figure 2 bottom). The trajecto-
ries of pain frequencies in a subsample of 194 participants over
a 4-week duration are depicted using a Sankey ’ s diagram
(
►Figure 3 top), which is a type of flow diagram for showing
factors’ states and transitions over time. 83 For easier visual
representation of the differential path transitions represented
by the “links” across 4 weeks, weekly frequencies are catego-
rized as low ( 10
times). The cut-off points were selected such that each 5-point
interval corresponds to approximately half a SD, based on the
sub-sample’ s mean (9.0) and SD (11.2) for weekly pain fre-
quency. The links connecting the bars ( “nodes”)d e p i c tt h e
variability in the pain frequency through time, both within and
between participants. The tile grid diagram (
►Figure 3 bot-
tom) shows dailyfluctuations in pain location and severity over
time for a single Phendo participant. Darker colors indicate
larger number of pain locations reported by the participant. For
example, the depicted participant reported severe pain in three
body locations on March 19, while on March 20, they reported
moderate and severe pain in six body locations each.
Quantitative Description of Variability
All participants who provided at least 7 days of tracking data
on pain were included in the variability analysis, yielding a
total of 43,539 person-level days from 1,534 Phendo partic -
ipants. Mean average (i.e., “mean of means ”) day-level pain
score was 7.75 (SD ¼ 5.61). Median average day-level pain
score was 6.21 (mean absolute deviation ¼ 3.79). Within-
Table 2 Descriptive statistics for the Phendo sample
Participant characteristics Mean (SD)/Frequency (%)
Age (y) ( N ¼ 5,915) 29.6 (6.9)
Median ¼ 28.9 (MAD ¼ 7.2)
Body mass index ( N ¼ 5,522)a 26.5 (7.0)
Median ¼ 24.7 (MAD ¼ 5.6)
Endometriosis diagnosis
Surgically con firmed
Clinician con firmed
5,224 (75.4)
1,701 (24.5)
Employment status
Employed 3,876 (55.9)
Not employed 856 (12.3)
Student 844 (12.1)
Unknown 1,349 (19.4)
Race/Ethnicity
Non-Hispanic White 4,861 (70.1)
Non-Hispanic Black 160 (2.3)
Hispanic (White or non-White) 327 (4.7)
Asian 156 (2.2)
Native American 45 (0.6)
Other (including mixed
race/ethnicity)
371 (5.3)
Unknown 1,005 (14.5)
Marital status
Married/in a domestic
partnership
3,298 (47.5)
Separated/divorced 191 (2.7)
Single, never married 2,086 (30.1)
Widowed 3 (0.04)
Unknown 1,016 (14.6)
Living environment
Urban 2,428 (35.0)
Suburban 2,489 (35.9)
Rural 992 (14.3)
Unknown 17 (0.38)
Primary work location
Home 1,481 (21.3)
Outside home 4,084 (58.9)
Unknown 1,360 (19.6)
Education level
High school or less 831 (2)
Some college 1,828 (26.3)
College or higher 3,251 (46.9)
Unknown 1,015 (14.6)
Abbreviations: BMI, body mass index; MAD, mean absolute deviation;
SD, standard deviation.
Note: Unknown indicates not tracked by the participant in the Phendo
app pro file, and therefore, data are not available.
aValues below 12 and over 70 are excluded from BMI summary statistics.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.774
person SD in day-level pain was 5.17 (SD ¼ 3.45). Expressed
in SDs to obtain a standardized measure of the within-person
variability75 (5.17/5.61), this yields a ratio of 0.92 and similar
to other effects sizes, can be interpreted as large. 75
Results
of the LMM analysis are provided in ►Table 4 .T h e
ICC was 0.42 (95% con fidence interval ¼ 0.40– 0.44) and was
statistically signi ficant (LRT Chi-square ¼ 22,600, p < 0.001).
This indicates that the 42% of the variance in daily pain is
attributed to between-participant variation and that pain
scores are signi ficantly correlated from day to day for each
participant. Within-person variance estimate was 38.72,
indicating that approximately 58% of the total variance in
daily pain is attributed to within-participant variation
(►Table 4 ). A plot of each participant ’ s estimated mean
scores and con fidence intervals are provided in ►Figure 4 ,
demonstrating the variability that occurs across participants
(x-axis), and within-participant (y-axis). Taken together,
these suggest that substantial variability occurs not just
between participants but also within-participant over
time. Of note, number of tracked days was not a signi ficant
Fig. 1 Prevalence of pain problems reported in the Phendo sample.
Table 3 Results of the two-sample test for equality of proportions
Pain problem
(SNOMED ID)
EHR counts
(proportion)
Phendo counts
(proportion)
Chi-square
statistic
95% CI z statistic
Abdominal a (200219) 1,603 (0.36) 2,690 (0.38) 6.14 ( p ¼ 0.01) /C0 0.04 to 0.004 /C0 2.47
Abdominal
(200219)
885 (0.20) 2,690 (0.38) 433.74 b /C0 0.20 to 0.17 /C0 20.82
Headache/Migraines
(378253/318736)
480 (0.05) 2,644 (0.38) 1,494 b /C0 0.33 to 0.31 /C0 38.65
Backache (134736) 299 (0.06) 3,414 (0.49) 2,198.30 b /C0 0.43 to 0.41 /C0 46.88
Chest (77670) 405 (0.09) 1,026 (0.14) 75.93 b /C0 0.06 to 0.04 /C0 8.71
Joint (77074) 334 (0.07) 733 (0.10) 27.83 b /C0 0.04 to 0.02 /C0 5.27
Dysuria (197684) 191 (0.04) 944 (0.13) 256.33 b /C0 0.10 to 0.08 /C0 16.01
Lower limb (4024561) 261 (0.05) 1,998 (0.28) 882 b /C0 0.24 to 0.21 /C0 29.69
Upper limb (4009890) 149 (0.03) 419 (0.06) 39.73 b /C0 0.03 to 0.06 /C0 6.30
Hip (200219) 35 (0.003) 570 (0.08) 338.49 b /C0 0.08 to 0.07 /C0 18.39
Bone (4129418) 16 (0.03) 570 (0.08) 338.49 b /C0 0.003 to 0.08 /C0 18.39
Pelvis (4147829) a 1,312 (0.29) 3,969 (0.57) 811.57 b /C0 0.29 to 0.25 /C0 28.48
Abbreviations: CI, con fidence interval; EHR, electronic health record.
Note: 95% con fidence interval built around the difference in proportions.
aIncludes the 885 conditions that are mapped under both “abdominal pain ” and “pain in pelvis. ”
bp < 0.0001.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 775
covariate in the variance estimation model (B ¼ 0.001, stan-
dard error ¼ 0.003, t ¼ 0.485, p ¼ 0.62), or correlated with
pain scores (Pearson ’ s r ¼ 0.01, t ¼ 0.41, p ¼ 0.68). Therefore,
it was not included in the final model as a covariate.
Additional Data Elements
Prevalence rates of reported affected daily function tasks are
provided in ►Table 5 . We identified a total of 22 distinct tasks
reported by the participants, who on average reported three
unique affected tasks (SD ¼ 2.2, range ¼ 1– 14). Working
(53.1%), getting out of bed (52.2%), standing (47.4%), and using
the toilet (47.3%) were the most frequently reported tasks. Of
note, 43% of the participants reported sleeping as an affected
task. Similarly, there were multiple physical mobility-related
tasks reported including sitting, walking, and climbing the
stairs, reported by at least 30% of the participants.
Prevalence rates of all self-management techniques are
provided in ►Figure 5 and ►Supplementary Table S3 (avail-
able in the online version). Participants reported a median of
three unique techniques (mean ¼ 3.21, SD ¼ 2.21, range ¼ 1–
14). Rest and using a heat pack were the most prevalent (52.4
and 50.7%, respectively). Assessment of effectiveness frequen-
cy indicated considerable variability in the reported helpful-
ness of the techniques. For example, breathing exercises
(reported as the third most frequently used technique by
38%) and ice packs were tracked as unhelpful 51 and 52% of
Fig. 2 Top: Prevalence of mild, moderate, and severe pains by body locati on as reported in the Phendo cohort. Each body area-intensity pair
counted once per participant. For all body locations, participants tracked predominantly moderate pain, with severe pain as second most
common, and mild as least common. Bottom: Mean proportion of severity reported for each body area normalized by total tracks of pain reports
and averaged across the sample. One-sided error bars were used for visual display purposes and represent standard deviations.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.776
the time on average. Moreover, even though rest was the most
prevalent technique, it was reported as helpful only 55.3% of
the time on average. On the other hand, acupuncture and
medical marijuana were the least prevalent (2.8 and 4.6%,
respectively) but most frequently effective techniques on
average (78.4 and 74.6% of the time, respectively).
Discussion
In this study, we investigate the potential of using direct
patient input via mobile technology to identify additional
data elements that can be obtained for contributing to
existing data sources in the context of enigmatic disease:
(1) improve prevalence estimates and characterization of
traditionally underdocumented diseases, (2) provide multi-
dimensional data (e.g., symptom severity, location, and
temporal fluctuations84) on the disease for generating infor-
mation that can aid in the personalization of care, and (3)
provide contextual information to characterize burden of
disease under real life circumstances and identify possible
points of intervention. To our knowledge, this study is the
first to provide a quantitative analysis to demonstrate how
participatory research-based self-tracking data compare
with EHR and what additional information could be
extracted for investigation of underdocumented diseases.
Our finding that pelvic pain is the most prevalent symp-
tom in our sample is in line with previous studies that use
self-reported questionnaires to assess pain symptomology in
endometriosis.
45 We extend this by reporting signi ficantly
fewer instances of pelvic pain and lack of any documentation
of several other endometriosis-related pain problems (e.g.,
dyschezia
85) in the EHR. Similarly, epigastric problems were
significantly underdocumented in the EHR, even though this
was the fourth most frequently reported problem in the
Phendo sample. This could be due to various reasons. There
could have been a higher number of patients presenting with
epigastric pain, but these instances might have been docu-
mented as “abdominal pain ” by the provider in the EHR
without providing further details. From the patient ’ s
Fig. 3 Top: Sankey diagram of pain frequencies over time in a sample of 194 Phendo participants over the course of a 4-week period. Weekly
frequencies are categorized into low ( 10 times), depicted by the different colors. The links depict
the variability in the pain frequency through time, both within participant, and between participants. Bottom: Daily fluctuations in pain intensity
over time for a sample individual in the Phendo cohort by severity and nu mber of pain locations. Darker color indicates larger number of pain
locations reported by the participant. For example, the depicted participant reported severe pain in three body locations on March 19, while on
March 20, they reported moderate and severe pain in six body locations each.
Table 4 Between- and within-person variance estimates
obtained from the linear mixed-effects model ( n ¼ 1,534)
Between-person
variance (t ^2)
Within-person
variance ( σ^2)
Variance SD
(95% CI)
Variance SD
(95% CI)
Pain
score
28.7 5.3
(5.1–5.5)
39.2 6.2
(6.1–6.2)
Abbreviations: CI, con fidence interval; ICC, intraclass correlation coef-
ficient; SD, standard deviation; SE, standard error.
Note: Phendo participants who provided at least 7 days of data were
included in the analysis. Number of days was not a signi ficant predictor
in the model (B ¼ 0.001, SE ¼ 0.003, t ¼ 0.485, p ¼ 0.62) and therefore
excluded from the final models for estimating variances and the ICC.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 777
perspective, previous studies report patient resistance to
disclosing pain, 86 and that patient ’ s physical pain can nega-
tively affect patient– provider communication.87 It is possible
that patients feel less stigmatized when sharing their symp-
toms through a mobile app rather than directly sharing with
their physician.
53,88 Another possibility could be lack of
adequate health insurance for access to point of care, which
has been linked to not only delays in diagnosis, but also
disparities in primary and/or specialist care and treat-
ment.
40,89 A similar study 90 comparing patient self-reported
surveys to EHR problem lists and chart notes for common
medical conditions reported that fewer than half of the 380
problems were shared across the data sources, and that 22%
of all diagnoses were found only in patient self-report. Our
findings reinforce these findings in demonstrating direct
patient input provides an opportunity to bring these differ-
ent data sources together to improve our understanding of
patient health history and disease status.
90 We further
demonstrate the added value of mHealth tools designed
based on participatory research to promote patient engage-
ment and self-tracking for improving our understanding of
diseases that are underdocumented and clinically not well
understood. Within the LHS framework, these have been
identified as opportunities for patient inclusion to democra-
tize the health care system.
57
Assessment of variation in pain indicated substantial
between- and within-individual variability in our sample,
which is in line with findings from other chronic pain
samples reported in the literature. 74 It has been long alluded
to that endometriosis is a heterogeneous disease that fluc -
tuates in symptoms within individual over time, and that the
magnitude of this fluctuation is moreover variable across
individuals, yet this has not been quanti fied. Our results
provide quantitative support for the dynamic nature of
Fig. 4 Plot of the person-level pain scores e stimated from the multilevel model ( n ¼ 1,534). Y-axis ( “effect range ”) represents pain scores. Each
black dot represents one participant and gray lines indicate 95% con fidence intervals. Distribution of points across the x-axis indicate large
variability across individuals (i.e., between-group variance). D ark gray lines indicate random effects that are statistically signi ficant.
Table 5 Prevalence of daily function tasks reported (%) in the
Phendo sample
Daily function task Count Prevalence (%)
Working 3,681 53.1
Getting out of bed 3,619 52.2
Standing 3,287 47.4
Using the toilet 3,281 47.3
Sitting 3,273 47.2
Walking 3,214 46.4
Socializing 3,122 45.1
Sleeping 2,950 42.6
Dressing 2,706 39.0
Climbing stairs 2,334 33.7
Running 2,294 33.1
Eating 2,292 33.1
Preparing food 2,230 32.2
Stretching 2,191 31.6
Lying down 1,917 27.6
Jumping 1,812 26.1
Sex 1,778 25.6
Housework 1,755 25.3
Shopping 1,638 23.6
Lifting 1,469 21.2
Kneeling 1,309 18.9
Bathing 854 12.3
Note: Out of the total 6,925, all 5,764 participants tracked at least one
daily function task in Phendo. Denominator of 6,925 is used to compute
prevalence rates.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.778
endometriosis pain and quantifying this variability is a
starting point for being able to derive clinically relevant
associations. That a patient ’ s pain symptoms over time
fluctuate almost as much as the variability in overall pain
experience observed across a sample of patients indicates, at
minimum, that information gathered about a patient at
single contact time point (e.g., doctor of fice visit) might
not be representative of the person ’ s overall disease experi-
ence as it unfolds over time. Similarly, attempts to character-
ize endometriosis through data collection designs relying
solely on EHR problem lists might yield incomplete or biased
results, findings supported by previous studies conducting in
other conditions.
14,16,90 From a clinical standpoint, pain
variability has been demonstrated to be predictive of treat-
ment response and disease outcomes. 79,91 For example, a
study79 reported that higher within-person pain variability
at baseline in a randomized controlled trial for a fibromyalgia
pain drug was predictive of placebo response and nonspecific
treatment effects. In another study with fibromyalgia
patients, authors demonstrated that between- and within-
person variability predicted disease symptomology clusters
and help identify disease phenotypes. In sum, frequent
monitoring can capture this dynamic nature of chronic
pain, yielding a more comprehensive and accurate disease
profile than what can be estimated through EHR which relies
on contact incidence.
Our observations on prevalence of impaired daily func -
tion are in line with others who report substantial disease
impact on QoL in endometriosis.
43,50,52 For example, Phendo
participants reported work as their most affected task and
almost half of the sample report their sleep being affected by
their endometriosis, findings previously reported in a survey
with 107 Puerto Rican women (mean age ¼ 34.5) with en-
dometriosis.
43 In addition, our findings on the prevalence of
socializing and walking as affected daily function tasks are
closely aligned with those reported in another sample of 193
Puerto Rican women with endometriosis (45.0 vs. 48% and
46.4 vs. 41.4%, respectively).
52 With respect to self-manage-
ment techniques, acupuncture was self-reported as effective
most of the time ( /C24 87%), though only 2.8% of the Phendo
participants reporting its use. Similarly, physical therapy was
reported by only 4.6% of the participants. These low frequen-
cies might indicate lack of access to such treatments, based
on prior evidence that insurance coverage, costs and changes
in insurance policy have been identi fied as signi ficant bar-
riers to receiving musculoskeletal (e.g., physical and pelvic)
therapy and rehabilitation services.
92 The ability to identify
these nuances in patient experiences with respect to their
disease management is another strength of using direct
patient input via mobile technology. Though beyond the
scope of the aims of this study, between-individual variabili-
ty in the effects of self-management techniques merits
further investigation. Taken together with our observations
on the self-management technique effect variability, these
findings not only underscore the burden of endometriosis
and its impact on daily living, but also the potential of using
Fig. 5 Average effect of self-management techniques reported by the Phendo participants (n ¼ 6,025). One-sided error bars were used for visual display
and indicate standard deviations. Proportions of each technique tracked as helpful or unhelpful (i.e.,“did not help” or “no effect”) out of the total number of
times tracked was averaged across all participants. There was significant variability as indicated by the standard deviations. For example, for the average user,
acupuncture was reported to be helpful approximately 75% of the time, and unhelpful approximately 25% of the time.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 779
direct input from the patient for identifying suitable targets
for intervention and effective strategies for symptom
management.
While mHealth and self-tracking for self-management
and improving health care have been widely advocated
both by the scienti fic community
93,94 and public health
agencies (e.g., WHO), 38 their use to generate better evi-
dence about chronic diseases is still rare. 95,96 We demon-
strate that self-tracking data can be valuable particularly
for conducting observational research on pain-related dis-
eases that are poorly understood and/or studied. Another
strength of our study is the participatory design aspect of
Phendo, which ensures that the items included in the app
are relevant to the patient population. This has been
identified as a way to improve study retention and long-
term adherence to tracking,
97 which is particularly impor-
tant when the goal is to increase documentation base for an
enigmatic disease.
60 Indeed, the prevalence rate of endo-
metriosis cases in our EHR database was 0.4%, which is
substantially lower than the reported 10% prevalence esti-
mated in the population. This provides further rationale for
focusing efforts to augment the typically relied upon EHR
databases through direct patient input to promote patient
engagement and inclusion in the data generation process,
which have been recommended as approaches for accom-
plishing the patient-centered-care system promoted within
the LHS framework.
57 Self-tracking facilitates documenta-
tion of not only severe pain, but also mild and moderate
pain instances. This can reduce the likelihood of over-
representing severe cases, a potential limitation of EHR.
41
Daily tracking allows for monitoring acute pain, which can
have distinctive differences in physiology compared with
chronic pain,
98 but still be associated to subsequent risk for
developing chronic pain in clinical populations, 99,100 par-
ticularly in women. 101 As such, information on temporal
fluctuations can improve our understanding of the dynamic
course of the disease and subsequently making timely
clinical decisions.
We note the potential of patient self-recording for im-
proving the completeness of demographic data in the health-
care systems. This paucity of data on common demographic
factors (e.g., race, ethnicity and education level)
102 and the
exclusive reliance on ICD-9 coding 103 in the EHR is a com-
monly reported issue in the literature. 104 In a recent
study,105 among the 2.4 million patients in New York Pres-
byterian Hospital healthcare system ’ s EHR (used also for
extracting the EHR sample in this study), race, or ethnicity
was unknown for 57%, compared with 86% when patients
directly recorded themselves. Accomplishing this is critical
for supporting precision medicine initiatives and reducing
health care disparities and inequities.
We note several limitations in our study. First, we had
independent samples of women with endometriosis, and
as such there might have been differences in characteristics
of the two samples that in fluence the proportion estimates.
Next, we were unable to conduct statistical tests of signi fi-
cance for pain intensity, frequency of their fluctuations,
and self-management techniques and daily function tasks
reported, as these data were not provided in the EHR for
our sample. Third, EHR data from the clinical warehouse
were available from January 1996 onward; therefore, our
search precludes identi fication of cases prior to that year.
Demographic factors were substantially missing in the
EHR, an observation that has been consistently reported
by others in the literature.
102,103,105 Likewise, some of the
demographic information was also missing in the Phendo
sample. The study samples therefore might not be repre-
sentative of endometriosis patients of some socioeconomic
and ethnic/racial backgrounds. Though we are not aware of
race/ethnicity as a predictive risk factor for endometriosis
diagnosis, we cannot ascertain if these results would have
been different with a more diverse sample. Approximately,
60% of the Phendo participants self-reported residing in the
United States and approximately 30% reported residing in
other countries, whereas EHR data were obtained from a
single (though ethnoracially and linguistically diverse)
metropolitan city and we do not have data on the patients ’
living or working environments. As such, there could be
differences between the two samples in comparison with
respect to environmental factors that could have in flu-
enced the outcomes. Similarly, we do not know the exact
breakdown of specialist versus general medicine practi-
tioners using the EHR system. Though beyond the scope of
the present study, future studies could investigate pain
problem documentation by practitioner specialty area.
Finally, we note the challenges of investigations in the
EHR, a topic extensively discussed in the literature,
106,107
which might have in fluenced our results. The ETL process
that converts the clinical data into the OMOP data tables is a
dynamic process that improves over time, but is not
completely error free. As such, the EHR search might have
missed some pain-related conditions. A recent study of EHR
problem list completeness and accuracy reports that pro-
viders struggle more with maintaining complete problem
lists for patients whose diseases status are less severe and
less symptomatic.
16 Accordingly, some of the patients iden-
tified in the EHR cohort might have reported additional pain-
related findings, but these might have not been documented
by the provider.
Conclusion
Patient self-tracking has been linked to increased self-ef fica-
cy, patient adherence, engagement as advocates in their
personalized care, and improved health outcomes.
108–110
This approach can enhance the research process by increas-
ing inclusion of those prone to health inequities,111 including
disease-level inequities as demonstrated herein using endo-
metriosis as a grounding example. Direct patient input via
self-tracking can facilitate collecting and sharing informa-
tion in a timely manner without increasing provider docu-
mentation responsibility and associated burden. In the same
way, the EHR are both the source of information and the
target of interventions; mHealth applications could play a
critical role by promoting patient engagement in aspects of
the health care system.
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.780
Clinical Relevance Statement
Use of mHealth technology for obtaining direct patient input
can supplement clinical documentation captured during
point of care to more accurately and comprehensively evalu-
ate patient health history and status. Patient inclusion in the
data generation and sharing process can further alleviate
burden due to EHR use, and enable patient as an active
participant in their care. This approach can be applied to
other conditions beyond endometriosis, especially those that
are chronic and fluctuating in symptoms over time.
Multiple Choice Questions
1. Which of the following is a primary endometriosis-related
problem detected in the self-tracking sample in line with
previous literature, but was found to be signi ficantly missing
in the electronic health record (EHR)?
a. Hip pain
b. Pelvic pain
c. Breast pain
d. Headache
Correct Answer:The correct answer is option b. Pelvic pain is a
primary characteristic symptom in endometriosis. It was the
most prevalent problem in the Phendo sample (57.3%, com-
pared with 29.8% in the EHR), a finding in line with previous
studies that assess pain symptomology in endometriosis.
45
Upon comparison, we further report significantly fewer instan-
ces of epigastric pain and dysuria in the EHR, as well as other
endometriosis-related pain problems (e.g., dyschezia85).
2. Which contributory aspect of direct patient input via
mobile technology is investigated in this study?
a. Increase the number of patients we can add into the
Learning Health System (LHS)
b. Increase the mHealth use among stakeholders of LHS
c. Expand upon the characterization of burden of disease in
the EHR
d. Increase documentation on diseases that are
underdocumented
Correct Answer: The correct answer is option d. While there
are numerous potential bene fits of including direct patient
input to complement information gathered from EHR for
conducting research and informing medical decisions, this
study focuses on how these data could help generate addi-
tional information on underdocumented diseases (e.g., en-
dometriosis) that would not be possible to obtain from EHR.
3. In addition to clinical conditions, what other type of
information has been indicated to be signi ficantly under-
documented in the EHR?
a. Patient preferences for treatment
b. Diagnosis dates
c. Demographic factors
d. Date of documentation
Correct Answer: The correct answer is option c. Information
on common demographic factors (e.g., race, ethnicity, and
education level) were substantially missing in the EHR in our
analyses, an observation that has been also reported by
others in the literature. For example, a study
105 reported
that among the 2.4 million patients in a large New York City
university health care system ’ s EHR, race, or ethnicity was
unknown for 57%, compared with 86% when patients directly
recorded themselves.
4. This study investigates endometriosis pain variability based
on patient self-reported data collected frequently over time.
What do the results of the linear mixed model (LMM) with
respect to the estimated intercepts (
►Figure 4 ) indicate?
a. The ratio of within-participant to group-level pain vari-
ability is comparable.
b. The mean day-level pain scores substantially vary across
participants.
c. There is signi ficant intraclass correlation of pain scores
over time.
d. Within-participant variation in daily pain accounts for
58% of the total model variance.
Correct Answer: The correct answer is option b. The use
of LMM with a random intercept for participant allows
estimation of a separate person-level mean in daily pain
scores, represented by the intercept. This random effect
was statistically signi ficant in the model, indicating that
there is substantial variability across participants in their
daily pain levels. This is depicted in
►Figure 4 where
variability across participants is apparent across the x-axis,
while within-participant variability is apparent across the y-
axis, represented by the variable 95% con fidence intervals.
Protection of Human and Animal Subjects
All procedures performed in studies involving human
participants were in accordance with the ethical stand-
ards of the institutional and/or national research commit-
tee and with the 1964 Helsinki Declaration and its later
amendments or comparable ethical standards. All proce-
dures followed were in accordance with ethical standards
of the responsible committee on human experimentation
(institutional and national) and with the Helsinki Decla-
ration of 1975, as revised in 2000. Informed consent
was obtained from all patients for being included in the
study.
• Available at https://itunes.apple.com/us/app/phendo/
id1145512423
• Available at https://play.google.com/store/apps/details?
id¼com.appliedinformaticsinc.phendo
Funding
This study received financial support from Columbia
University Data Science Institute Postdoctoral Fellowship,
Endometriosis Foundation of America, National Science
Foundation (grant number: 1344668), and from National
Institutes of Health, U.S. National Library of Medicine
(grant number: R01 LM013043).
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 781
Conflict of Interest
None declared.
References
1 Institute of Medicine (US) Roundtable on Evidence-Based Medi-
cine Olsen L, Aisner D, McGinnis JM, eds. The Learning Health-
care System: Workshop Summary. Washington, DC: National
Academies Press; 2007
2 McGinnis JM, Powers B, Grossmann C. Digital Infrastructure
for the Learning Health System: The Foundation for Continu-
ous Improvement in Health and Health Care: Workshop
Series Summary. Washington, DC: National Academies Press;
2011
3 Friedman CP, Wong AK, Blumenthal D. Achieving a nationwide
learning health system. Sci Transl Med 2010;2(57):57cm29
4 Riley WT, Glasgow RE, Etheredge L, Abernethy AP. Rapid, re-
sponsive, relevant (R3) research: a call for a rapid learning health
research enterprise. Clin Transl Med 2013;2(01):10
5 Greene SM, Reid RJ, Larson EB. Implementing the learning health
system: from concept to action. Ann Intern Med 2012;157(03):
207– 210
6 Green LW. Making research relevant: if it is an evidence-based
practice, where ’ s the practice-based evidence? Fam Pract 2008;
25(Suppl 1):i20 – i24
7 Cortez A, Hsii P, Mitchell E, Riehl V, Smith P. Conceptualizing a
data infrastructure for the capture, use, and sharing of patient-
generated health data in care delivery and research through
2024. Accenture. . Available at: https://www.healthit.gov/sites/
default/files/onc_pghd_practical_guide.pdf?plat-
form¼hootsuite. Accessed January, 2018
8 Casey JA, Schwartz BS, Stewart WF, Adler NE. Using electronic
health records for population health research: a review of methods
and applications. Annu Rev Public Health 2016;37:61– 81
9 Lin KJ, Singer DE, Glynn RJ, Murphy SN, Lii J, Schneeweiss S.
Identifying patients with high data completeness to improve
validity of comparative effectiveness research in electronic
health records data. Clin Pharmacol Ther 2018;103(05):
899– 905
10 Jensen PB, Jensen LJ, Brunak S. Mining electronic health records:
towards better research applications and clinical care. Nat Rev
Genet 2012;13(06):395 – 405
11 Acker B, Bronnert J, Brown T, et al. Problem list guidance in the
EHR. J AHIMA 2011;82(09):52 – 58
12 Blondeau C. Pocket Glossary of Health Information Management
and Technology. 3rd Edition Chicago, IL: AHIMA; 2011
13 Daskivich TJ, Abedi G, Kaplan SH, et al. Electronic health record
problem lists: accurate enough for risk adjustment? Am J Manag
Care 2018;24(01):e24 – e29
14 Wang M, Cyhaniuk A, Cooper DL, Iyer NN. Identi fication of
patients with congenital hemophilia in a large electronic health
record database. J Blood Med 2017;8:131 – 139
15 Wang YC, Shimbo D, Muntner P, Moran AE, Krakoff LR, Schwartz
JE. Prevalence of masked hypertension among US adults with
nonelevated clinic blood pressure. Am J Epidemiol 2017;185
(03):194– 202
16 Wang EC -H, Wright A. Characterizing outpatient problem list
completeness and duplications in the electronic health record.
J Am Med Inform Assoc 2020;27(08):1190 – 1197
17 Ommaya AK, Cipriano PF, Hoyt DB, et al. Care-centered clinical
documentation in the digital environment: solutions to alleviate
burnout. NAM Perspectives . Available at: https://nam.edu/wp-
content/uploads/2018/01/Care-Centered-Clinical-Documenta-
tion.pdf. Accessed January 29, 2018
18 Collier R. Electronic health records contributing to physician
burnout. Can Med Assoc . Available at: https://europepmc.org/
article/med/29133547. Accessed 2017
19 Gardner RL, Cooper E, Haskell J, et al. Physician stress and
burnout: the impact of health information technology. J Am
Med Inform Assoc 2019;26(02):106 – 114
20 West SL, Johnson W, Visscher W, Kluckman M, Qin Y, Larsen A.
The challenges of linking health insurer claims with electronic
medical records. Health Informatics J 2014;20(01):22 – 34
21 Adane K, Gizachew M, Kendie S. The role of medical data in
efficient patient care delivery: a review. Risk Manag Healthc
Policy 2019;12:67 – 73
22 Rhodes ET, Laffel LM, Gonzalez TV, Ludwig DS. Accuracy of
administrative coding for type 2 diabetes in children, adoles-
cents, and young adults. Diabetes Care 2007;30(01):141 – 143
23 Valikodath NG, Newman-Casey PA, Lee PP, Musch DC, Niziol LM,
Woodward MA. Agreement of ocular symptom reporting be-
tween patient-reported outcomes and medical records. JAMA
Ophthalmol 2017;135(03):225 – 231
24 Cahill S, Makadon H. Sexual orientation and gender identity data
collection in clinical settings and in electronic health records: a key
to ending LGBT health disparities. LGBT Health 2014;1(01):34– 41
25 Bagley SC, Altman RB. Computing disease incidence, prevalence
and comorbidity from electronic medical records. J Biomed
Inform 2016;63:108 – 111
26 Almalki M, Gray K, Sanchez FM. The use of self-quanti fication
systems for personal health information: big data management
activities and prospects. Health Inf Sci Syst 2015;3(Suppl 1):S1
27 Swan M. Emerging patient-driven health care models: an exam-
ination of health social networks, consumer personalized medi-
cine and quanti fied self-tracking. Int J Environ Res Public Health
2009;6(02):492– 525
28 Khovanskaya V, Baumer EPS, Cosley D, Voida S, Gay G. Everybody
knows what you’ re doing: a critical design approach to personal
informatics. Proceedings of the SIGCHI Conference on Human
Factors in Computing Systems . Available at: https://stephen.
voida.com/uploads/Publications/Publications/khovanskaya-
chi13.pdf. Accessed 2013
29 Figueiredo M, Caldeira C, Chen Y, Zheng K. Routine self-tracking
of health: reasons, facilitating factors, and the potential impact
on health management practices. AMIA Annu Symp Proc 2018;
2017:706– 714
30 Shapiro M, Johnston D, Wald J, Mon D. Patient-generated health
data. RTI International . Available at: https://www.healthit.gov/
sites/default/files/rti_pghd_whitepaper_april_2012.pdfApril.
Accessed April 2012
31 Boyer GS, Templin DW, Goring WP, et al. Discrepancies between
patient recall and the medical record. Potential impact on
diagnosis and clinical assessment of chronic disease. Arch Intern
Med 1995;155(17):1868 – 1872
32 Sampson UKA, Kaplan RM, Cooper RS, et al. Reducing health
inequities in the U.S.: recommendations from the NHLBI ’ sh e a l t h
inequities think tank meeting. J Am Coll Cardiol 2016;68(05):
517– 524
33 Ahmed S, Berzon RA, Revicki DAInternational Society for Quality
of Life Research. , et al; . The use of patient-reported outcomes
(PRO) within comparative effectiveness research: implications
for clinical practice and health care policy. Med Care 2012;50
(12):1060– 1070
34 Pichon A, Schiffer K, Horran E, Bakken S, Mamykina L, Elhadad N.
Divided We Stand: The Collaborative Work of Patients and Pro-
viders in an Enigmatic Chronic Disease. [under anonymous re-
view]. . Available at: http://www.columbia.edu/ /C24 ab3886/docs/
APichon_CV_Jan2020.pdf. Accessed 2020
35 Payne TH, Corley S, Cullen TA, et al. Report of the AMIA EHR-2020
task force on the status and future direction of EHRs. J Am Med
Inform Assoc 2015;22(05):1102 – 1110
36 Rycroft-Malone J, Seers K, Titchen A, Harvey G, Kitson A, McCor-
mack B. What counts as evidence in evidence-based practice?
J Adv Nurs 2004;47(01):81 – 90
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.782
37 Dullabh P, Hovey L, Heaney-Huls K, Rajendran N, Wright A, Sittig
DF. Application programming interfaces in health care: findings
from a current-state sociotechnical assessment. Appl Clin Inform
2020;11(01):59– 69
38 Executive B. mHealth: use of appropriate digital technologies for
public health: report by the Director-General. GenevaWorld
Health Organization; Available at: https://apps.who.int/iris/bit-
stream/handle/10665/274134/B142_20-en.pdf?sequence ¼1&
isAllowed¼y. Accessed November 27, 2017
39 Tamaresis JS, Irwin JC, Goldfien GA, et al. Molecular classification
of endometriosis and disease stage using high-dimensional
genomic data. Endocrinology 2014;155(12):4986 – 4999
40 Fourquet J, Zavala DE, Missmer S, Bracero N, Romaguera J, Flores
I. Disparities in healthcare services in women with endometri-
osis with public vs private health insurance. Am J Obstet Gynecol
2019;221(06):623.e1 – 623.e11
41 De Graaff AA, D ’ Hooghe TM, Dunselman GA, Dirksen CD, Hum-
melshoj L, Simoens SWERF EndoCost Consortium. The signi fi-
cant effect of endometriosis on physical, mental and social
wellbeing: results from an international cross-sectional survey.
Hum Reprod 2013;28(10):2677 – 2685
42 Simoens S, Dunselman G, Dirksen C, et al. The burden of
endometriosis: costs and quality of life of women with endome-
triosis and treated in referral centres. Hum Reprod 2012;27(05):
1292– 1299
43 Fourquet J, Gao X, Zavala D, et al. Patients ’ report on how
endometriosis affects health, work, and daily life. Fertil Steril
2010;93(07):2424– 2428
44 Rogers PA, D ’ Hooghe TM, Fazleabas A, et al. Priorities for endo-
metriosis research: recommendations from an international
consensus workshop. Reprod Sci 2009;16(04):335 – 346
45 Schliep KC, Mumford SL, Peterson CM, et al. Pain typology and
incident endometriosis. Hum Reprod 2015;30(10):2427 – 2438
46 Soliman AM, Coyne KS, Gries KS, Castelli-Haley J, Snabes MC,
Surrey ES. The effect of endometriosis symptoms on absenteeism
and presenteeism in the workplace and at home. J Manag Care
Spec Pharm 2017;23(07):745 – 754
47 Whiteman MK, Hillis SD, Jamieson DJ, et al. Inpatient hysterec -
tomy surveillance in the United States, 2000-2004. Am J Obstet
Gynecol 2008;198(01):34.e1 – 34.e7
48 Health NIo Estimates of funding for various research, condition,
and disease categories (RCDC). Available at: https://report.nih.gov/
categorical_spending.aspx. Published 2019. Accessed March 15,
2020
49 Garry R. Is insulin resistance an essential component of PCOS?:
the endometriosis syndromes: a clinical classi fication in the
presence of aetiological confusion and therapeutic anarchy. Hum
Reprod 2004;19(04):760 – 768
50 Nnoaham KE, Hummelshoj L, Webster PWorld Endometriosis
Research Foundation Global Study of Women ’ s Health consor-
tium. , et al; . Impact of endometriosis on quality of life and work
productivity: a multicenter study across ten countries. Fertil
Steril 2011;96(02):366 – 373
51 Farland LV, Horne AW. Disparity in endometriosis diag-
noses between racial/ethnic groups. BJOG 2019;126(09):1115 –
1116
52 Fourquet J, Báez L, Figueroa M, Iriarte RI, Flores I. Quanti fication
of the impact of endometriosis symptoms on health-related
quality of life and work productivity. Fertil Steril 2011;96(01):
107– 112
53 Chen EH, Shofer FS, Dean AJ, et al. Gender disparity in analgesic
treatment of emergency department patients with acute ab-
dominal pain. Acad Emerg Med 2008;15(05):414 – 418
54 Leresche L. Defining gender disparities in pain management. Clin
Orthop Relat Res 2011;469(07):1871 – 1877
55 Ghiasi M, Kulkarni MT, Missmer SA. Is endometriosis more
common and more severe than it was 30 years ago? J Minim
Invasive Gynecol 2020;27(02):452 – 461
56 Budrionis A, Bellika JG. The learning healthcare system: where are
we now? A systematic review. J Biomed Inform 2016;64:87– 92
57 Galvin HK, Petersen C, Subbian V, Solomonides A. Patients as
agents in behavioral health research and service provision:
recommendations to support the learning health system. Appl
Clin Inform 2019;10(05):841 – 848
58 McKillop M, Mamykina L, Elhadad N. Designing in the dark:
eliciting self-tracking dimensions for understanding enigmatic
disease. Proceedings of the 2018 CHI Conference on Human
Factors in Computing Systems . Available at: http://people.dbmi.
columbia.edu/noemie/papers/18chi.pdf. Accessed 2018
59 McKillop M, Voigt N, Schnall R, Elhadad N. Exploring self-
tracking as a participatory research activity among women
with endometriosis. J Particip Med 2016;8:e17
60 Ensari I, Elhadad N. mHealth For Research: Participatory
Research Applications to Gain Disease Insights. In Digital Health:
Mobile and Wearable Devices for Participatory Health Applica-
tions. Eds. Syed-Abdul S, Zhu X, Fernandez-Luque L. Elsevier,
2020. Forthcoming. ISBN: 978-0128200773
61 Friedman C, Rubin J, Brown J, et al. Toward a science of learning
systems: a research agenda for the high-functioning Learning
Health System. J Am Med Inform Assoc 2015;22(01):43 – 50
62 Hripcsak G, Duke JD, Shah NH, et al. Observational health data
sciences and informatics (OHDSI): opportunities for observational
researchers. Stud Health Technol Inform 2015;216:574– 578
63 Hripcsak G, Albers DJ. Correlating electronic health record con-
cepts with healthcare process events. J Am Med Inform Assoc
2013;20(e2):e311– e318
64 United States Census Bureau QuickFacts. New York City, New
YorkUnited States Census Bureau. Available at: https://data.
census.gov/cedsci/all?q¼new%20york%20cit-
y&g¼1600000US3651000&hidePreview ¼false&tid¼ACSDP1-
Y2018.DP05&vintage¼2018. Accessed 2020
65 Ta CN, Dumontier M, Hripcsak G, Tatonetti NP, Weng C. Columbia
Open Health Data, clinical concept prevalence and co-occurrence
from electronic health records. Sci Data 2018;5:180273 – 180273
66 Awad E, Ahmed HAH, Yousef A, Abbas R. Ef ficacy of exercise on
pelvic pain and posture associated with endometriosis: within
subject design. J Phys Ther Sci 2017;29(12):2112 – 2115
67 The Observational Medical Outcomes Partnership (OMOP) Com-
mon Data Model. Available at: https://ohdsi.github.io/Common-
DataModel/background.html. Accessed 2020
68 International Health Terminology Standards Development Or-
ganization SNOMED CT Worldwide. Available at: http://www.
ihtsdo.org/snomed-ct/snomed-ct-worldwide. Accessed 2016
69 Zini EM, Lanzola G, Bossi P, Quaglini S. An environment for
guideline-based decision support systems for outpatients mon-
itoring. Methods Inf Med 2017;56(04):283 – 293
70 Ramakrishnan N, Hanauer D, Keller B. Mining electronic health
records. Computer 2010;(10):77 – 81
71 McKillop MM. Phenotyping endometriosis from observational
health data. Columbia University . Available at: https://academ-
iccommons.columbia.edu/doi/10.7916/d8-1est-dh56. Accessed
March 18, 2019
72 Melzack R. The McGill Pain Questionnaire: major properties and
scoring methods. Pain 1975;1(03):277 – 299
73 Simborg DW, Star field BH, Horn SD, Yourtee SA. Information
factors affecting problem follow-up in ambulatory care. Med
Care 1976;14(10):848 – 856
74 Bartley EJ, Robinson ME, Staud R. Pain and fatigue variability
patterns distinguish subgroups of fibromyalgia patients. J Pain
2018;19(04):372– 381
75 Salthouse TA. Implications of within-person variability in cog-
nitive and neuropsychological functioning for the interpretation
of change. Neuropsychology 2007;21(04):401 – 411
76 Urteaga I, McKillop M, Elhadad N. Learning endometriosis
phenotypes from patient-generated data. NPJ Digit Med 2020;
3:88
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al. 783
77 Wilson EB. Probable inference, the law of succession, and statis-
tical inference. J Am Stat Assoc 1927;22(158):209 – 212
78 Newcombe RG. Interval estimation for the difference between
independent proportions: comparison of eleven methods. Stat
Med 1998;17(08):873 – 890
79 Harris RE, Williams DA, McLean SA, et al. Characterization and
consequences of pain variability in individuals with fibromyal-
gia. Arthritis Rheum 2005;52(11):3670 – 3674
80 Stoffel MA, Nakagawa S, Schielzeth H. rptR: Repeatability estima-
tion and variance decomposition by generalized linear mixed ‐
effects models. Methods Ecol Evol 2017;8(11):1639– 1644
81 Hox JJ, Moerbeek M, Van de Schoot R. Multilevel Analysis:
Techniques and Applications. Routledge 2010
82 Nakagawa S, Schielzeth H. Repeatability for Gaussian and non-
Gaussian data: a practical guide for biologists. Biol Rev Camb
Philos Soc 2010;85(04):935 – 956
83 Huang C -W, Lu R, Iqbal U, et al. A richly interactive exploratory
data analysis and visualization tool using electronic medical
records. BMC Med Inform Decis Mak 2015;15:92 – 92
84 Bougie O, Healey J, Singh SS. Behind the times: revisiting endome-
triosis and race. Am J Obstet Gynecol 2019;221(01):35.e1– 35.e5
85 Seracchioli R, Mabrouk M, Guerrini M, et al. Dyschezia and
posterior deep in filtrating endometriosis: analysis of 360 cases.
J Minim Invasive Gynecol 2008;15(06):695 – 699
86 Cagle J, Bunting M. Patient reluctance to discuss pain: under-
standing stoicism, stigma, and other contributing factors. J Soc
Work End Life Palliat Care 2017;13(01):27 – 43
87 Norouzinia R, Aghabarari M, Shiri M, Karimi M, Samami E.
Samami EJGjohs. Communication barriers perceived by nurses
and patients. Glob J Health Sci 2015;8(06):65 – 74
88 Hoffmann DE, Tarzian AJ. The girl who cried pain: a bias against
women in the treatment of pain. J Law Med Ethics 2001;29(01):
13– 27
89 As-Sanie S, Black R, Giudice LC, et al. Assessing research gaps and
unmet needs in endometriosis. Am J Obstet Gynecol 2019;221
(02):86– 94
90 Weiskopf NG, Cohen AM, Hannan J, Jarmon T, Dorr DA. Towards
augmenting structured EHR data: a comparison of manual chart
review and patient self-report. AMIA Annu Symp Proc 2020;
2019:903– 912
91 Farrar JT, Troxel AB, Haynes K, et al. Effect of variability in the 7-
day baseline pain diary on the assay sensitivity of neuropathic
pain randomized clinical trials: an ACTTION study. Pain 2014;
155(08):1622– 1631
92 Carvalho E, Bettger JP, Goode AP. Insurance coverage, costs, and
barriers to care for outpatient musculoskeletal therapy and
rehabilitation services. N C Med J 2017;78(05):312 – 314
93 Genes N, Violante S, Cetrangol C, Rogers L, Schadt EE, Chan YY.
From smartphone to EHR: a case report on integrating patient-
generated health data. NPJ Digit Med 2018;1(01):23
94 Alexander S. mHealth Technologies for the Self-management of
Diabetes in the Older Population. ACM SIGACCESS Accessibility
and Computing 2015;(111):14 – 18
95 Steinhubl SR, Muse ED, Topol EJ. The emerging field of mobile
health. Sci Transl Med 2015;7(283):283rv3
96 Faurholt-Jepsen M, Munkholm K, Frost M, Bardram JE, Kessing
LV. Electronic self-monitoring of mood using IT platforms in
adult patients with bipolar disorder: a systematic review of the
validity and evidence. BMC Psychiatry 2016;16(01):7
97 Perski O, Blandford A, West R, Michie S. Conceptualising engage-
ment with digital behaviour change interventions: a systematic
review using principles from critical interpretive synthesis.
Transl Behav Med 2017;7(02):254 – 267
98 Honoré P, Menning PM, Rogers SD, Nichols ML, Mantyh PW.
Neurochemical plasticity in persistent in flammatory pain. In: .
Progress in brain research. Vol 129 Elsevier; 2000:357 – 363
99 Sinatra R. Causes and consequences of inadequate management
of acute pain. Pain Med 2010;11(12):1859 – 1871
100 Tasmuth T, Kataja M, Blomqvist C, von Smitten K, Kalso E.
Treatment-related factors predisposing to chronic pain in
patients with breast cancer – a multivariate approach. Acta Oncol
1997;36(06):625– 630
101 Poleshuck EL, Katz J, Andrus CH, et al. Risk factors for chronic
pain following breast cancer surgery: a prospective study. J Pain
2006;7(09):626– 634
102 Fremont A, Lurie N. Eliminating health disparities: measurement
and data needs. Appendix D, The role of racial and ethnic data
collection in eliminating disparities in health care Washington
(DC): National Academies Press (US); 2004
103 Birkhead GS, Klompas M, Shah NR. Uses of electronic health
records for public health surveillance to advance public health.
Annu Rev Public Health 2015;36(01):345 – 359
104 Douglas MD, Dawes DE, Holden KB, Mack D. Missed policy
opportunities to advance health equity by recording demo-
graphic data in electronic health records. Am J Public Health
2015;105(Suppl 3):S380 – S388
105 Polubriaginof FCG, Ryan P, Salmasian H, et al. Challenges with
quality of race and ethnicity data in observational databases.
J Am Med Inform Assoc 2019;26(8-9):730 – 736
106 Kiepek W, Sengstack PP. An evaluation of system end-user
support during implementation of an electronic health record
using the model for improvement framework. Appl Clin Inform
2019;10(05):964– 971
107 Thyvalikakath TP, Duncan WD, Siddiqui ZNational Dental PBRN
Collaborative Group. , et al; . Leveraging electronic dental record
data for clinical research in the national dental PBRN practices.
Appl Clin Inform 2020;11(02):305 – 314
108 Charmel PA, Frampton SB. Building the business case for patient-
centered care. Healthc Financ Manage 2008;62(03):80 – 85
109 Chiauzzi E, Rodarte C, DasMahapatra P. Patient-centered activity
monitoring in the self-management of chronic health conditions.
BMC Med 2015;13(01):77
110 Korotitsch WJ, Nelson-Gray RO. An overview of self-monitoring
research in assessment and treatment. Psychol Assess 1999;11
(04):415
111 Chase HS, Radhakrishnan J, Shirazian S, Rao MK, Vawdrey DK.
Under-documentation of chronic kidney disease in the electron-
ic health record in outpatients. J Am Med Inform Assoc 2010;17
(05):588– 594
Applied Clinical Informatics Vol. 11 No. 5/2020
Self-Tracking Data and Clinical Documentation in Endometriosis Ensari et al.784
Text is read by the "Ask this paper" AI Q&A widget below.
Extraction quality varies by source — PMC NXML preserves structure
cleanly, OA-HTML may include some navigation residue, and OA-PDF can
have broken hyphenation. The publisher copy
(via DOI)
is the canonical version.