Prescribing smartphone applications for physical activity promotion in primary care: modeling health gain and cost savings (Preprint)

BACKGROUND Inadequate physical activity is a substantial cause of health loss globally with this loss attributable to such diseases as coronary heart disease, diabetes, stroke, and certain forms of cancer. OBJECTIVE We aimed to assess the potential impact of the prescription of smartphone applications (apps) in primary care settings on physical activity levels, health gains (in quality-adjusted life years (QALYs)), and health system costs in New Zealand (NZ). METHODS A proportional multistate lifetable model was used to estimate the change in physical activity levels and to predict resultant health gains in QALYs and health system costs over the remaining lifespan of the NZ population alive in 2011 at a 3% discount rate. RESULTS The modeled intervention resulted in an estimated 430 QALYs (95% uncertainty interval: 320 to 550), with net cost-savings of NZ $2.2 million (2018 US $1.6 million) over the remaining lifespan of the 2011 NZ population. On a per capita basis, QALY gains were generally larger in women than men, and larger in Māori than non-Māori. The health impact and cost-effectiveness of the intervention were highly sensitive to assumptions around intervention uptake and decay. For example, the scenario analysis with the largest benefits, which assumed a five-year maintenance of additional physical activity levels, delivered 1750 QALYs and NZ $22.5 million in cost-savings. CONCLUSIONS The prescription of smartphone apps for promoting physical activity in primary care settings is likely to generate modest health gains and cost-savings at the population level, in this high-income country. Such gains may increase with ongoing improvements in app design and increased health worker promotion to patients.