The roles of motivational interviewing and self-efficacy on outcomes and cost-effectiveness of a community-based exercise intervention for inactive middle-older aged adults

Abstract

Increasing physical activity (PA) among inactive middle-older aged adults in rural communities is challenging. This study investigates the efficacy of a PA intervention supporting inactive adults in rural/ semi-rural communities. Inactive participants enrolled on either a single signposting session (n=427), or multi-session pathway combining signposting with motivational interviewing (MI) (n=478). Pre-post outcomes data assessed activity levels (IPAQ-S; SISEM), self-efficacy (NGSE) and well-being (WHO-5). Measures were repeated at longitudinal time points (26, 52 weeks) for the MI pathway. Outcomes were contrasted with results from an unmatched comparison group receiving treatment as usual (TAU). Cost-utility (QALY-ICER) and return on investment (NHS-ROI; QALY-ROI) were estimated for short (5 years), medium (10 years) and long (25 years) time horizons. Both pathways significantly increased participants’ PA. The MI pathway resulted in significantly greater increases in PA than signposting-only and TAU. Improvements in psychological outcomes (NGSE; WHO-5) were significantly greater in the MI pathway than TAU. Longitudinal results indicated MI pathway participants sustained increases in light-intensity PA at 52 weeks (p<.001; ηp2=.16). Regression analyses found baseline self-efficacy predicted increased PA at 52 weeks, while baseline wellbeing did not. The relationship between self-efficacy and PA increased successively across time points. However, the magnitude of participants’ increased self-efficacy did not predict PA at any time point. Both pathways were cost-effective and costsaving for participants aged ≥ 61 years from the short time horizon, with the MI pathway having greater return on investment estimates. Overall, MI increased efficacy of a signposting PA intervention, and was cost-saving for older adults.