Cost-effectiveness of strength exercise or aerobic exercise compared with usual care for patients with knee osteoarthritis: secondary results from a multiarm randomised controlled trial in Norway

Abstract

Objectives To evaluate the 1-year cost-effectiveness of strength exercise or aerobic exercise compared with usual care for patients with symptomatic knee osteoarthritis (OA), from a societal and healthcare perspective. Design Cost-effectiveness analysis embedded in a three-arm randomised controlled trial. Participants and setting A total of 161 people with symptomatic knee OA seeking Norwegian primary or secondary care were included in the analyses. Interventions Participants were randomised to either 12 weeks of strength exercise (n=54), 12 weeks of aerobic exercise (n=53) or usual care (n=54). Outcome measures Quality-adjusted life-years (QALYs) estimated by the EuroQol-5 Dimensions-5 Levels, and costs related to healthcare utilisation and productivity loss estimated in euros (€), aggregated for 1 year of follow-up. Cost-effectiveness was expressed with mean incremental cost-effectiveness ratios (ICERs). Bootstrapping was used to estimate ICER uncertainty. Results From a 1-year societal perspective, the mean cost per patient was €7954, €8101 and €17 398 in the strength exercise, aerobic exercise and usual care group, respectively. From a 1-year healthcare perspective, the mean cost per patient was €848, €2003 and €1654 in the strength exercise, aerobic exercise and usual care group, respectively. Mean differences in costs significantly favoured strength exercise and aerobic exercise from a 1-year societal perspective and strength exercise from a 1-year healthcare perspective. There were no significant differences in mean QALYs between groups. From a 1-year societal perspective, at a willingness-to-pay threshold of €27 500, the probability of strength exercise or aerobic exercise being cost-effective was ≥98%. From a 1-year healthcare perspective, the probability of strength exercise or aerobic exercise being cost-effective was ≥97% and ≥76%, respectively. Conclusion From a 1-year societal and healthcare perspective, a 12-week strength exercise or aerobic exercise programme is cost-effective compared with usual care in patients with symptomatic knee OA. Trial registration number NCT01682980.