Optimizing Mobile Health Messaging in Digital Interventions: A Choice Experiment

Mobile messaging interventions provide a scalable, low-cost channel to support health behavior change, yet optimal content design remains uncertain, particularly regarding gain- versus loss-framed messages. Guided by the Multiphase Optimization Strategy (MOST), this study examined framing preferences among older adults to inform user-centered digital intervention design for alcohol reduction. In a choice experiment, N=1,348 participants aged 50 years and older evaluated 174 messages (86 gain- and 86 loss-framed) across 6,740 pairwise comparisons. Participants selected which message they would prefer to receive as part of a health messaging program. Gain-framed messages were preferred in 57.8% of direct gain–loss comparisons (95% CI: 0.561–0.594; χ²(1)=83.66, p<.001), independent of message placement or trial order. Substantial variability was observed across individual message content. Results indicate a consistent preference for gain framing but emphasize that framing alone does not determine preference, underscoring the need to study other behavioral mechanisms that can be optimized.