Effects of cannabis ingestion on endometriosis-associated pelvic pain and related symptoms

Justin Sinclair, Laura Collett, Abbott J, Jason Abbott, David W. Pate, Pate DW, Jerome Sarris, Mike Armour
PloS one · 2021 · vol. 16(10) , pp. e0258940 · doi:10.1371/journal.pone.0258940 · PMID:34699540 · PMC8547625 · W3182583282
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This retrospective study of endometriosis patients found cannabis reduced pelvic pain, GI symptoms, and improved mood, with inhaled forms being more effective for pain and oral forms for GI symptoms and mood.

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This retrospective cohort study used anonymized archival data from the StrainprintTM medicinal cannabis smartphone app to examine self-rated cannabis efficacy among 252 users who reported endometriosis, across symptom clusters of pelvic pain/cramps, gastrointestinal symptoms, and mood-related symptoms, accounting for dosage form, dose, and THC:CBD ratio. Across 16,187 analyzed cannabis use sessions (2017–2020), pain was the most common reason for use, while gastrointestinal symptoms showed the greatest self-reported improvement after cannabis; inhaled forms had higher efficacy for pain and oral forms were superior for mood and gastrointestinal outcomes, with a statistically significant but clinically small effect of THC:CBD ratio depending on ingestion method. A key limitation is reliance on self-reported symptom ratings with no control group and short, fixed reassessment windows (20 minutes for inhaled vs 90 minutes for oral), plus dosing and symptom selection occurring through app prompts. This paper is centrally about endometriosis—assessing how cannabis ingestion affects endometriosis-associated pelvic pain and related symptoms via real-world app-recorded outcomes.

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Abstract

BACKGROUND: The use of cannabis for symptoms of endometriosis was investigated utilising retrospective archival data from Strainprint Technologies Ltd., a Canadian data technology company with a mobile phone application that tracks a range of data including dose, mode of administration, chemovar and their effects on various self-reported outcomes, including pelvic pain. METHODS: A retrospective, electronic record-based cohort study of StrainprintTM users with self-reported endometriosis was conducted. Self-rated cannabis efficacy, defined as a function of initial and final symptom ratings, was investigated across the included symptom clusters of cramps, pelvic pain, gastrointestinal pain, nausea, depression, and low libido. Cannabis dosage form, dose and cannabinoid ratio information was also recorded. RESULTS: A total number of 252 participants identifying as suffering endometriosis recorded 16193 sessions using cannabis between April 2017 and February 2020. The most common method of ingestion was inhalation (n = 10914, 67.4%), with pain as the most common reported symptom being treated by cannabis (n = 9281, 57.3%). Gastrointestinal symptoms, though a less common reason for cannabis usage (15.2%), had the greatest self-reported improvement after use. Inhaled forms had higher efficacy for pain, while oral forms were superior for mood and gastrointestinal symptoms. Dosage varied across ingestion methods, with a median dose of 9 inhalations (IQR 5 to 11) for inhaled dosage forms and 1 mg/mL (IQR 0.5 to 2) for other ingested dosage forms. The ratio of THC to CBD had a statistically significant, yet clinically small, differential effect on efficacy, depending on method of ingestion. CONCLUSIONS: Cannabis appears to be effective for pelvic pain, gastrointestinal issues and mood, with effectiveness differing based on method of ingestion. The greater propensity for use of an inhaled dosage delivery may be due to the rapid onset of pain-relieving effects versus the slower onset of oral products. Oral forms appeared to be superior compared to inhaled forms in the less commonly reported mood or gastrointestinal categories. Clinical trials investigating the tolerability and effectiveness of cannabis for endometriosis pain and associated symptoms are urgently required.
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Intro

Endometriosis is a common, chronic inflammatory condition in women characterised by the presence of endometrial-like tissue found outside the uterus [ 1 ]. Prevalence rates of the disease have been estimated at between 5% [ 2 ] and 11% [ 3 ] of reproductive-aged women, impacting an estimated 176 million women worldwide. [ 4 ]. In addition, endometriosis can also affect post-menopausal women, ranging from between 2–5% of cases [ 5 ]. Endometriosis is associated with a variety of symptoms including chronic pelvic pain, fatigue, dysmenorrhoea (period pain), dyspareunia (painful sex), dyschezia (painful bowel movements) and dysuria (pain related to urination) [ 6 , 7 ]. In addition, co-morbid anxiety and/or depression in the endometriosis cohort is frequently reported [ 8 , 9 ], along with irritable bowel syndrome (IBS)-like gastrointestinal symptoms [ 10 , 11 ] and significant fatigue [ 6 ]. These symptoms contribute to substantial reductions in many aspects of quality-of-life including social, academic, work and sexual relationships [ 12 , 13 ]. In addition, endometriosis causes a noteworthy cost of illness burden to the economy, mostly due to lost productivity [ 14 – 16 ]. Recent studies have suggested that a dysfunction in the endocannabinoid system (ECS) is present in endometriosis patients [ 17 , 18 ], and that aspects of endometriosis-associated pain may be targeted by modulating the ECS [ 19 ]. Previous research on the use of illicit cannabis in women with endometriosis has shown promise in the treatment of endometriosis pain and co-morbid symptoms such as poor sleep, gastrointestinal upset and mood disorders [ 20 – 22 ]. However, these findings were all based on self-reported data and could not be reliably used to determine the relative effectiveness of different modes of cannabis administration, dose amount, cannabinoid ratios, or other determining factors (such as patient age), all of which may influence clinical outcomes. This study sought to investigate the self-rated effectiveness, dosage forms, dosage amount and cannabinoid ratios of quality-assured legal cannabis products that women are using in the Canadian regulated market, via their use of the Strainprint TM smartphone application (“app”), which is used to track legal cannabis product usage for medicinal purposes.

Results

A total number of 252 participants were identified as having endometriosis, with a total of 16,193 sessions. Six sessions were excluded from this dataset due to ingestion method (suppository, n = 1), outlying THC (>500 mg/mL, n = 3), outlying CBD (>500 mg/mL, n = 1), and negative dosage (n = 1), yielding a total of 16,187 sessions included in the final analysis. Prevalence of cannabis use was rated highest for the pain subgroup (n = 9281/57.3%), followed by gastrointestinal (n = 4715/29.1%) and mood (n = 2191/13.5%). The mean age at the beginning of each session of women identifying as having endometriosis within the Strainprint TM dataset was 35 years, with the majority using the app for approximately 5.5 months (See Table 1 ). Pulmonary administration was the favoured dosage form, with inhaled forms accounting for 67.4% of all dosage forms utilised by the cohort: Vapouriser (40.6%), Smoked (25.9%), dab bubbler or concentrate (0.9%). Orally ingested dosage forms were the next most utilised, accounting for 32.3% of the cohort: Oils (25.0%), Pills (3.5%), Edible products (2.4%), Tincture as spray or oral drops (1.4%). Topicals (0.2%) and transdermals (0.1%) had minimal reported usage in this dataset. Pelvic Pain (42.4% of all participants) was the primary clinical indication for use of cannabis, with Gastrointestinal Distress (15.2%) and Cramps (14.9%) following in frequency. Nausea (13.9%) and Depression (13.2%) were also notable findings, with Low Libido (0.3%) being the least reported symptom. Dosage varied according to ingestion method, but not for the symptom being treated, with the highest median dose being taken by those using inhalation (9 mg/mL or puff, IQR: 5, 11, n = 10,914). Lowest median dose was taken by those treating pain and mood via oral dosage forms, with a median dose of 1 mg/mL, capsule or piece (with an IQR of 0.5 to 2, n = 5220). The median dose for topical application was 2 mg/mL (IQR: 1.5 to 20, n = 53). THC and CBD levels (and THC/CBD ratios) varied widely, depending on the ingestion method ( Fig 1 ). Inhaled methods typically had a high THC to CBD ratio, with a median % or mg/mL THC of 16 (IQR 8 to 19.6), a median % or mg/mL CBD of 0.07 (IQR 0 to 8.01) and a median THC/CBD ratio of 90 (IQR 0.6 to 304). Ingested dosage forms exhibited the opposite tendency, having a high CBD to THC ratio, with a median for THC of 2.5 (IQR 1.0 to 12), a median for CBD of 13.5 (IQR 5 to 25) and a median THC/CBD ratio of 0.08 (IQR 0.04 to 1). The median amounts of THC and CBD for topical dosage forms was equal (median ratio of 1, IQR 0.4 to 13.2). The THC/CBD ratio remained similar as median ratios across the symptoms: Pain 0.95 (IQR 0.1 to 197) vs . Gastrointestinal Distress 0.88 (IQR 0.08 to 242) vs . Mood 0.89 (IQR 0.08 to 220), although approximately 8% less THC than CBD was used overall. Results of the multilevel model are reported in Table 2 . Overall, cannabis was shown to have a positive effect, with a modelled mean baseline efficacy rating of 31.98 (95% CI 31.26 to 32.71, p<0.0001). The symptom with the largest effect was seen for gastrointestinal symptoms, with an estimated increase in efficacy of 9.02 (95% CI 8.15 to 9.90, p<0.0001) compared to pain. Mood symptoms had effects not significantly different from baseline of pain. Despite there being relatively few participants reporting use of topical administrations, this had the strongest effect of all the ingestion methods, with an estimated increase in efficacy of 13.64 (95% CI 6.11 to 21.17, p = 0.0004) in comparison to the baseline for inhalation. Orally ingested products had a slightly lower efficacy than the baseline observed for inhaled cannabis (-2.11 with 95% CI –3.23 to –1.00, p = 0.0002). Ingestion methods varied according to symptom. Examination of the interaction between symptom group and ingestion method revealed an increase in efficacy when taking oral cannabis for gastrointestinal symptoms, with an estimate of 7.82 (95% CI 6.26 to 9.37, p<0.0001) adding to the effect of oral and gastrointestinal seen alone. There was also an increase in efficacy for those treating mood with orally ingested forms (5.16 with 95% CI 2.96 to 7.36, p<0.0001). Effects of topical administration on gastrointestinal and mood symptoms were intriguing, but should be treated with caution as these subgroups had minimal usage in this dataset. The effect of THC/CBD ratio gave an increase in efficacy of 1.72 (95% CI 1.22 to 2.23, p<0.0001) for every ten-fold increase in THC. Age also had a statistically significant effect, with an increase in efficacy of 0.26 (95% CI 0.20 to 0.31, p<0.0001) for each year increase in age, with older women having better overall efficacy. As seen in Fig 1 , the relationship between THC and CBD levels differed between ingestion methods, and the model showed that efficacy also differed subsequently. There was no evidence of a difference in efficacy according to the ratio of THC to CBD between topical and inhaled treatments. However, there was a difference between inhaled and orally ingested cannabis in combination with the ratio of THC to CBD, where for ingested methods, there was a reduction in efficacy of 4.75 (95% CI 5.62 to 3.88) for every 10-fold increase in THC compared to CBD (an increase in efficacy for every 10-fold increase in CBD compared to THC).

Conclusions

With emerging evidence internationally demonstrating that women are utilising illicit cannabis as a self-management strategy for the pain and the associated symptoms of endometriosis, this paper demonstrates that Canadian women are also utilising legally obtained and quality-assured products to manage endometriosis symptoms across domains such as pelvic pain, gastrointestinal symptoms and mood. Cannabis appears to be effective across all reported symptoms, with a noted propensity for inhaled delivery due to the potential increased speed of onset of effects versus the slower onset of oral products, particularly for pelvic pain. Conversely, oral forms appeared to be superior for the less reported mood and gastrointestinal categories, possibly due to higher CBD concentrations in the products utilised. Whilst topical products demonstrated a good effect on pain, due to a very small data set, caution should be exercised in interpreting or extrapolating from this data. The importance of quality-assured and standardised (i.e., cannabinoid potency and ratios) cannabis products to obtain reproduceable clinical results, and to mitigate possible adverse effects due to potential adulteration or contamination of products, is an important clinical consideration for medicinal cannabis moving forward, particularly when considering the urgent need for clinical trials investigating the safety, tolerability and effectiveness of cannabis for endometriosis pain and associated symptoms.

Materials|Methods

Strainprint Technologies Ltd. is a Canadian-based data and analytics company that provides a free mobile phone app that allows individuals to prospectively track medicinal cannabis usage, including the varieties of cannabis, dosage form, dosage and changes in symptom severity of users over time. During the initial session, users enter basic demographic information such as age and gender, and then identify the medical conditions or symptoms they are experiencing as part of the onboarding process. Prior to using cannabis, users open the app and identify the symptom for which they will be using cannabis, which is then recorded as a “session”. A session was defined as the process by which participants select the symptom(s) they are currently experiencing (allowing categorization), self-rate the severity of the symptom(s) using an 11-point numerical rating scale (0 being lowest severity to 10 being highest) prior to cannabis use, select the product and dosage form they will use to address the aforementioned symptom(s), and record the dose taken. Product choices are pre-populated from a list of over 6500 laboratory-verified products in the Strainprint TM database offered by licenced medicinal Cannabis cultivators and distributors, including the records of the delta -9-tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations and ratios, in addition to dominant terpene expressions within the database. Whilst the baseline severity of each symptom is obtained prior to taking the dose, the app prompts users after a set time period (20 minutes for inhaled forms and 90 minutes for oral forms) to revaluate the specific symptom severity scores. Archival data in Excel format was provided by Strainprint Technologies Ltd. for the period April 2017 until February 2020. During this period, only pre-populated and lab-verified product selection was available, with no ability for manual entry by users. Demographic data and the breakdown of clinical indications and dosage forms from the data set are noted in Table 1 . To facilitate multilevel analysis, symptoms were classified into clinically meaningful subgroups a priori , arranged as either “Pain” (including pelvic pain and cramps), “Gastrointestinal” (including gastrointestinal pain and nausea) and “Mood” (incorporating depression and low libido). Further characterisation was applied to the dosage form utilised by the users and included “Oral” (including edibles [mg], oils [mL], capsules [mg], tinctures [mL] or sprays [mL], “Topical” (including transdermal and topical) and “Inhaled” forms (“puffs” for smoked and vapourised). Due to the nature of the research project utilising fully anonymised retrospective archival datasets, this project was exempt from ethical review by the Western Sydney University Human Ethics Committee as per the National Health & Medical Research Council (NHMRC) National Statement [ 23 ]. All individuals who register to use the Strainprint TM app signed a Consent to Collection and Use of Data form for research purposes Self-rated cannabis efficacy, defined as a function of initial and final symptom ratings before and after cannabis use was utilised. Where x = initial symptom rating (score out of 10) and y = final symptom rating (score out of 10). Statistical analysis was carried out using multilevel linear regression to examine the effect of various independent factors on efficacy rating. Participants and sessions were classed as random effects to take into account dependence between observations in the same session from the same user, and all other factors were classed as fixed effects. Additionally, the ratio of THC to CBD was hypothesised to be an important determinant of efficacy, and due to the fact that some participants’ recorded cannabinoids with zero amounts of THC or CBD, trace levels (0.0001) of THC or CBD were assigned to these data points for the purpose of modelling, so that ratios could be calculated and missing data minimised.

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Condition tags

endometriosischronic_pelvic_pain

MeSH descriptors

Analgesics Endometriosis Medical Marijuana Pelvic Pain Administration, Oral Administration, Oral Adult Adult Analgesics Analgesics Analgesics Endometriosis Endometriosis Female Female Humans Humans Medical Marijuana Medical Marijuana Medical Marijuana

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