Prospective Measurement of Daily Health Behaviors: Modeling Temporal Patterns in Missing Data, Sexual Behavior, and Substance Use in an Online Daily Diary Study of Gay and Bisexual Men
INTRODUCTION Interactive voice response (IVR) technology uses the telephone to collect patient reports. This study examined whether IVR adherence during a year-long clinical trial was related to subject retention in the trial. METHODS As part of a randomized, double-blind, placebo-controlled study of daily multivitamin supplementation for recurrent aphthous stomatitis, 160 study participants were asked to make 1 weekly IVR call for the one-year study duration. RESULTS The 114 subjects who completed the study made 90.5% of their expected number of IVR calls, as compared to 55.7% of expected calls made by the 46 subjects who withdrew prematurely (p<0.001). Subjects who successfully completed the study were also more likely to initiate their IVR calls as compared to subjects who withdrew from the study (p<0.001). A multivariable model incorporating different adherence variables was able to successfully predict retention status of more than 80% of subjects. IVR adherence during the first few weeks of study participation was strongly predictive of subsequent retention and successful completion of this one-year study. DISCUSSION Subjects who withdrew prematurely had more missing data than study completers, even after accounting for period of study participation, potentially introducing bias into IVR results. Sub-optimal adherence to weekly IVR might provide an early signal of subsequent premature withdrawal in clinical trials. IVR adherence could be used as a screening tool during a trial period, to identify subjects most likely to stay on long clinical trials. CONCLUSION IVR adherence may be useful in anticipating retention in long-term clinical studies.