Economic evaluation of a rehabilitation program integrating exercise, self-management, and active coping strategies for chronic knee pain

Abstract

Objective: To conduct an economic evaluation of the Enabling Self-Management and Coping with Arthritic Knee Pain through Exercise (ESCAPE-knee pain) program.

Methods: Alongside a clinical trial, we estimated the costs of usual primary care and participation in ESCAPE-knee pain delivered to individuals (Indiv-rehab) or groups of 8 participants (Grp-rehab). Information on resource use and informal care received was collected during face-to-face interviews. Cost-effectiveness and cost-utility were assessed from between-group differences in costs, function (primary clinical outcome), and quality-adjusted life years (QALYs). Cost-effectiveness acceptability curves were constructed to represent uncertainty around cost-effectiveness.

Results: Rehabilitation (regardless of whether Indiv-rehab or Grp-rehab) cost 224 pounds (95% confidence interval [95% CI] 184 pounds, 262 pounds) more per person than usual primary care. The probability of rehabilitation being more cost-effective than usual primary care was 90% if decision makers were willing to pay 1,900 pounds for improvements in functioning. Indiv-rehab cost 314 pounds/person and Grp-rehab 125 pounds/person. Indiv-rehab cost 189 pounds (95% CI 168 pounds, 208 pounds) more per person than Grp-rehab. The probability of Indiv-rehab being more cost-effective than Grp-rehab increased as willingness to pay (WTP) increased, reaching 50% probability at WTP 5,500 pounds. The lack of differences in QALYs across the arms led to lower probabilities of cost-effectiveness based on this outcome.

Conclusion: Provision of ESCAPE-knee pain had small cost implications, but it was more likely to be cost-effective in improving function than usual primary care. Group rehabilitation reduces costs without compromising clinical effectiveness, increasing probability of cost-effectiveness.

Figure 1

Cost-effectiveness acceptability curves: probability (given as percentage) that 1) rehabilitation (individual or group) is cost-effective compared with usual primary care and 2) Indiv-rehab is cost-effective compared with Grp-rehab, for a range of values of health care commissioners' willingness to pay for an increase in the proportion of participants improving in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC-func) by 15% at 6 months, from a health/social care perspective. Rehabilitation = costs of individual and group rehabilitation programs combined; Indiv-rehab = rehabilitation program delivered to individual participants; Grp-rehab = rehabilitation program delivered to groups of 8 participants; £ = English pounds sterling. Conversion rate to US dollars at 2003 purchasing power parity: £1 = $1.613.

Figure 2

Cost-effectiveness acceptability curves: probability that each treatment strategy is cost-effective compared with the other 2, for a range of values of decision makers' willingness to pay for an additional quality-adjusted life year (QALY), from a health/social care perspective at 6 months. Indiv-rehab = rehabilitation program delivered to individual participants; Grp-rehab = rehabilitation program delivered to groups of 8 participants; £ = English pounds sterling. Conversion rate to US dollars at 2003 purchasing power parity: £1 = $1.613.