Identifying chest-worn light logger adherence: a validation study

Background Light exposure plays an important role in overall health because it entrains circadian rhythms. Recent technological advances in wearable light loggers allow measurement daily light exposure habits. Using a chest-worn light logger, our goal was to 1) develop methodology for differentiating adherent versus non-adherent use, and 2) define differences in lighting intensity in indoor and outdoor environments, to improve data reliability in future clinical studies using this technology.

Five testers used a 10-channel chest worn light logging device under different conditions of wear and non-wear, and across a variety of indoor and outdoor lighting environments. Measurements from the light logger (photopic illuminance, device orientation, accelerometer data, time of day) were used to train and validate a logistic regression model to differentiate wear from non-wear and correct nighttime placement. This model was then applied to 20 adolescents and young adults with migraine who wore the light logger device for one week. Furthermore, measurements of photopic illuminance and melanopic equivalent daytime illuminance (mEDI) of indoor versus outdoor lighting environments were compared to identify the optimal distinction point between darker indoor and brighter outdoor environments for the chest-worn light logger.

Movement, device orientation, light, and time-of-day used as predictors in a logistic regression model had excellent differentiation between wear, non-wear and nighttime use (AUC 0.93 – 0.94), and retained good-to-excellent differentiation when applied to the validation dataset (AUC 0.84 – 0.91). When this model was applied to 20 participants with migraine, we found that 92.9% of participant-days and 71.4% of participant-nights demonstrated at least 80% appropriate use. For differentiating indoor and outdoor lighting environments, the optimal cut-point was 442 lux for photopic illuminance, and 412 lux for mEDI.

We demonstrate that internal measurements from a chest-worn light logging device can reliably differentiate wear from non-wear. We also found that the optimal cut-off to differentiate indoor and outdoor lighting environments was similar though slightly lower than then 1,000 lux cut-offs traditionally used to define bright light conditions. These findings can be used to improve data reliability in studies of everyday light exposure in clinical populations using chest-worn light loggers. Competing Interest Statement C.P.G.: Dr. Patterson Gentile is currently funded by the National Institutes of Health/National Institute of Neurological Disorders and Stroke (K23 NS124986). C.L.S.: Dr. Szperka has received research/grant support from the PCORI. Dr. Szperka or her institution have received compensation for her consulting work for Eli Lilly; Teva Pharmaceutical Industries Ltd; Upsher-Smith Laboratories, LLC; Abbvie; and Lundbeck. Dr. Szperka has intellectual property as the inventor of the text-based headache diary used in the study. She did not receive any financial compensation related to this paper. G.K.A.: Dr. Aguirre receives funding/grant support from the National Institute of Neurological Disorders and Stroke, the National Eye Institute, and the Binational Science Foundation. A.T., R.S., B.M.P., and N.R. do not have conflicts of interest. Funding Statement This work was supported by the Childrens Hospital of Philadelphia Foerderer Grant and by the National Institutes of Health National Institute of Neurological Disorders and Stroke (K23NS124986 to C.P.G) and The National Eye Institute (P30EY001583 to G.K.A.) and the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under Award Number (R25HD101365 to A.T.). Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The protocol received approval from the Institutional Review Board at Children's Hospital of Philadelphia and was in accordance with the Declaration of Helsinki. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Footnotes Conflict of interest statement: Commercial Relationships Disclosures: C.P.G.: Dr. Patterson Gentile is currently funded by the National Institutes of Health/National Institute of Neurological Disorders and Stroke (K23 NS124986). C.L.S.: Dr. Szperka has received research/grant support from the PCORI. Dr. Szperka or her institution have received compensation for her consulting work for Eli Lilly; Teva Pharmaceutical Industries Ltd; Upsher-Smith Laboratories, LLC; Abbvie; and Lundbeck. Dr. Szperka has intellectual property as the inventor of the text-based headache diary used in the study. She did not receive any financial compensation related to this paper. G.K.A.: Dr. Aguirre receives funding/grant support from the National Institute of Neurological Disorders and Stroke, the National Eye Institute, and the Binational Science Foundation. A.T., R.S., B.M.P., and N.R. do not have conflicts of interest. Financial support: This work was supported by the Children’s Hospital of Philadelphia Foerderer Grant, and by the National Institutes of Health National Institute of Neurological Disorders and Stroke (K23NS124986 to C.P.G) and The National Eye Institute (P30EY001583 to G.K.A.), and the Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health under Award Number (R25HD101365 to A.T.). Data Availability Data collected by the researchers is available for this current study upon request to the authors. Data from the participants with migraine that have been previously published is not available due to legal limitations based on the consent form. Abbreviations - AUC - Area under the curve - CHOP - Children’s Hospital of Philadelphia - CI - Confidence interval - mEDI - Melanopic Equivalent Daylight Illuminance - ROC - receiver operating curve - TAT - Time above threshold