The cost-effectiveness of a home-based exercise programme for the treatment of knee pain in the community
Objectives: o To determine the prevalence of knee pain in the population aged ≥45 years. o To determine the benefit or otherwise of regular home exercise and telephone contact in reducing the burden of knee pain in the community. o To determine the economic burden of knee pain from a societal perspective. o To determine the cost-effectiveness and cost-utility of the compared interventions. Design: An initial postal questionnaire regarding knee pain was sent to 9296 individuals aged ≥45 years registered with two large general practices in Nottingham. This was followed by a two-year, single-blind, randomised factorial trial. Treatment arms included: exercise therapy, telephone social support, a placebo health food product and no intervention. Economic data were collected prospectively alongside the trial. Analysis was conducted on an intent-to-treat basis. Primary outcome: Self-reported knee pain at 24 months. This was assessed using the Western Ontario MacMaster's Universities Osteoarthritis Index (WOMAC) - a knee specific questionnaire. Results: The postal questionnaire was returned by 65% of the study population. The prevalence of self-reported knee pain in the community in those aged ≥45 years was 32% (35% in females and 28% in males). Costs incurred during the 6-month period prior to randomisation showed medical costs for the treatment of knee pain to be 7% of total medical costs and 11% of primary care costs. Annual societal costs were estimated to be £48 per person. The intervention study demonstrated that a simple, home-exercise programme could reduce self-reported knee pain, knee stiffness and knee related physical disability after 24 months (p=<0.001, 0.01 and <0.001 respectively). Effect sizes were modest, but improvements were incremental to normal care. The number needed to treat (NNT) in order to achieve a ≥ 50% reduction in pain at 24 months for individuals allocated to the exercise programme was between 8 and 13. Neither telephone contact nor the placebo dolomite tablet contributed significantly to the observed reduction in pain. The cost per person of delivering the two-year exercise programme was £ 113. Analysis of GP records revealed no change in medical costs during the trial. Cost-effectiveness analysis suggested hat the cost per unit change on the WOMAC pain scale was £ 108. The cost-effectiveness of achieving a ≥ 50% reduction in pain in a single individual (based on NNT figures) was £1,012. Conclusion: Knee pain is common in the general UK population aged ≥45 years and incurs an estimated cost of £218 to £350 million per annum (excluding indirect costs) in 1996 prices. The burden of knee pain could be reduced by the implementation of a cost-effective primary care-based exercise programme, although such improvements are likely to be modest.