@Article{info:doi/10.2196/10143, author="Bricker, Jonathan B and Sridharan, Vasundhara and Zhu, Yifan and Mull, Kristin E and Heffner, Jaimee L and Watson, Noreen L and McClure, Jennifer B and Di, Chongzhi", title="Trajectories of 12-Month Usage Patterns for Two Smoking Cessation Websites: Exploring How Users Engage Over Time", journal="J Med Internet Res", year="2018", month="Apr", day="20", volume="20", number="4", pages="e10143", keywords="engagement; trajectories; eHealth; websites; tobacco; smoking; acceptance and commitment therapy; smokefree.gov; patient participation; telemedicine; tobacco use cessation; smoking cessation", abstract="Background: Little is known about how individuals engage with electronic health (eHealth) interventions over time and whether this engagement predicts health outcomes. Objective: The objectives of this study, by using the example of a specific type of eHealth intervention (ie, websites for smoking cessation), were to determine (1) distinct groups of log-in trajectories over a 12-month period, (2) their association with smoking cessation, and (3) baseline user characteristics that predict trajectory group membership. Methods: We conducted a functional clustering analysis of 365 consecutive days of log-in data from both arms of a large (N=2637) randomized trial of 2 website interventions for smoking cessation (WebQuit and Smokefree), with a primary outcome of 30-day point prevalence smoking abstinence at 12 months. We conducted analyses for each website separately. Results: A total of 3 distinct trajectory groups emerged for each website. For WebQuit, participants were clustered into 3 groups: 1-week users (682/1240, 55.00{\%} of the sample), 5-week users (399/1240, 32.18{\%}), and 52-week users (159/1240, 12.82{\%}). Compared with the 1-week users, the 5- and 52-week users had 57{\%} higher odds (odds ratio [OR] 1.57, 95{\%} CI 1.13-2.17; P=.007) and 124{\%} higher odds (OR 2.24, 95{\%} CI 1.45-3.43; P<.001), respectively, of being abstinent at 12 months. Smokefree users were clustered into 3 groups: 1-week users (645/1309, 49.27{\%} of the sample), 4-week users (395/1309, 30.18{\%}), and 5-week users (269/1309, 20.55{\%}). Compared with the 1-week users, 5-week users (but not 4-week users; P=.99) had 48{\%} higher odds (OR 1.48, 95{\%} CI 1.05-2.07; P=.02) of being abstinent at 12 months. In general, the WebQuit intervention had a greater number of weekly log-ins within each of the 3 trajectory groups as compared with those of the Smokefree intervention. Baseline characteristics associated with trajectory group membership varied between websites. Conclusions: Patterns of 1-, 4-, and 5-week usage of websites may be common for how people engage in eHealth interventions. The 5-week usage of either website, and 52-week usage only of WebQuit, predicted a higher odds of quitting smoking. Strategies to increase eHealth intervention engagement for 4 more weeks (ie, from 1 week to 5 weeks) could be highly cost effective. Trial Registration: ClinicalTrials.gov NCT01812278; https://www.clinicaltrials.gov/ct2/show/NCT01812278 (Archived by WebCite at http://www.webcitation.org/6yPO2OIKR) ", issn="1438-8871", doi="10.2196/10143", url="http://www.jmir.org/2018/4/e10143/", url="https://doi.org/10.2196/10143", url="http://www.ncbi.nlm.nih.gov/pubmed/29678799" }