The effect of preferences for print versus telephone interventions on compliance and attrition in a randomized controlled physical activity trial

Objectives: Research indicates that non-face-to-face interventions, such as telephone and print, are effective for increasing physical activity. However, no study that we are aware of, has examined the effect of preference for intervention channel (e.g., telephone, print) on physical activity. This study examined the effect of receiving one's non-preferred intervention channel (print versus telephone) on physical activity, study compliance, and attrition. Methods: Participants (n = 239) were sedentary adults aged 18-65 years who participated in a randomized controlled trial examining the efficacy of telephone and print-based motivationally tailored physical activity interventions. Prior to randomization, participants indicated their preference for the print or telephone intervention. We examined the effect of intervention preference on physical activity behavior, compliance with the protocol (e.g., completing physical activity logs and questionnaires), and study attrition at 6 and 12 months. Results: At baseline, participants were significantly more likely to prefer the telephone versus the print intervention (56.1% versus 42.7%; p < 0.01). There were no differences on physical activity, compliance, and attrition between participants who received their preferred or non-preferred intervention. Conclusions: Our findings suggest that among motivated volunteer participants, concerns regarding how receiving one's non-preferred intervention influences outcome, compliance, and attrition in randomized controlled physical activity trials may not be warranted.