@Article{info:doi/10.2196/mhealth.8162, author="Druce, Katie L and McBeth, John and van der Veer, Sabine N and Selby, David A and Vidgen, Bertie and Georgatzis, Konstantinos and Hellman, Bruce and Lakshminarayana, Rashmi and Chowdhury, Afiqul and Schultz, David M and Sanders, Caroline and Sergeant, Jamie C and Dixon, William G", title="Recruitment and Ongoing Engagement in a UK Smartphone Study Examining the Association Between Weather and Pain: Cohort Study", journal="JMIR Mhealth Uhealth", year="2017", month="Nov", day="01", volume="5", number="11", pages="e168", keywords="epidemiology; mHealth; chronic pain; methods", abstract="Background: The huge increase in smartphone use heralds an enormous opportunity for epidemiology research, but there is limited evidence regarding long-term engagement and attrition in mobile health (mHealth) studies. Objective: The objective of this study was to examine how representative the Cloudy with a Chance of Pain study population is of wider chronic-pain populations and to explore patterns of engagement among participants during the first 6 months of the study. Methods: Participants in the United Kingdom who had chronic pain (≥3 months) and enrolled between January 20, 2016 and January 29, 2016 were eligible if they were aged ≥17 years and used the study app to report any of 10 pain-related symptoms during the study period. Participant characteristics were compared with data from the Health Survey for England (HSE) 2011. Distinct clusters of engagement over time were determined using first-order hidden Markov models, and participant characteristics were compared between the clusters. Results: Compared with the data from the HSE, our sample comprised a higher proportion of women (80.51{\%}, 5129/6370 vs 55.61{\%}, 4782/8599) and fewer persons at the extremes of age (16-34 and 75+). Four clusters of engagement were identified: high (13.60{\%}, 865/6370), moderate (21.76{\%}, 1384/6370), low (39.35{\%}, 2503/6370), and tourists (25.44{\%}, 1618/6370), between which median days of data entry ranged from 1 (interquartile range; IQR: 1-1; tourist) to 149 (124-163; high). Those in the high-engagement cluster were typically older, whereas those in the tourist cluster were mostly male. Few other differences distinguished the clusters. Conclusions: Cloudy with a Chance of Pain demonstrates a rapid and successful recruitment of a large, representative, and engaged sample of people with chronic pain and provides strong evidence to suggest that smartphones could provide a viable alternative to traditional data collection methods. ", issn="2291-5222", doi="10.2196/mhealth.8162", url="http://mhealth.jmir.org/2017/11/e168/", url="https://doi.org/10.2196/mhealth.8162", url="http://www.ncbi.nlm.nih.gov/pubmed/29092810" }