Costs and Cost-Effectiveness at 12 and 24 Months of an Enhanced Web-Based Physical Activity Intervention for Latina Adults: Secondary Analysis of a Randomized Controlled Trial.

BACKGROUND: We previously established the efficacy and cost-effectiveness of a web-based physical activity (PA) intervention for Latina adults, which increased PA, but few participants met PA guidelines, and long-term maintenance was not examined. A new version with enhanced intervention features was found to outperform the original intervention in long-term guideline adherence. OBJECTIVE: This study aimed to determine the costs and cost-effectiveness of the enhanced multitechnology PA intervention compared to the original web-based intervention in increasing minutes of activity and adherence to guidelines. METHODS: Latina adults (N=195) were randomly assigned to receive a Spanish-language, individually tailored web-based PA intervention (original) or the same intervention with additional phone calls and interactive SMS text messaging (enhanced). PA was measured at baseline, 12 months (end of active intervention), and 24 months (end of tapered maintenance) using self-report (7-day PA recall interview) and ActiGraph accelerometers. Costs were estimated from a payer perspective and included all features needed to deliver the intervention, including staff, materials, and technology. Cost-effectiveness was calculated as the cost per additional minute of PA added over the intervention and the incremental cost-effectiveness ratios of each additional person meeting guidelines. RESULTS: At 12 months, the costs of delivering the interventions were US $16 per person per month in the enhanced arm and US $13 per person per month in the original arm. These costs decreased to US $14 and US $8 at 24 months, respectively. At 12 months, each additional minute of self-reported activity in the enhanced group cost US $0.09 compared to US $0.11 in the original group (US $0.19 vs US $0.16 for ActiGraph), with incremental costs of US $0.05 per additional minute in the enhanced group beyond the original group. At the end of the maintenance period (24 mo), costs per additional minute decreased to US $0.06 and US $0.05 (US $0.12 vs US $0.10 for ActiGraph), with incremental costs of US $0.08 per additional minute in the enhanced group (US $0.20 for ActiGraph). Costs of meeting PA guidelines at 12 months were US $705 in the enhanced group compared to US $503 in the original group and increased to US $812 and US $601 at 24 months, respectively. The incremental cost-effectiveness ratio for meeting guidelines at 24 months was US $1837 (95% CI US $730.89-US $2673.89) per additional person in the enhanced group compared to the original group. CONCLUSIONS: The enhanced intervention was more expensive but yielded better long-term maintenance of activity, costing US $1837 per extra person meeting guidelines beyond those in the original group. Both conditions were low cost relative to other medical interventions. The enhanced intervention may be preferable in populations at high risk, where more investment in meeting guidelines could yield more cost savings. TRIAL REGISTRATION: ClinicalTrials.gov NCT03491592; https://clinicaltrials.gov/study/NCT03491592. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1186/s13063-022-06575-4.