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| Lifestyle interventions for knee pain in overweight and obese adults aged >=45: economic evaluation of randomised controlled trial |
| Barton G R, Sach T H, Jenkinson C, Doherty M, Avery A J, Muir K R |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. CRD summary This study examined the cost-effectiveness of four lifestyle interventions; dietary advice plus quadriceps strengthening exercises, dietary advice alone, quadriceps strengthening exercises alone, and leaflet provision. Patients were aged 45 years or older, with knee pain, and a body mass index of 28 or more. Dietary advice plus strengthening exercises was the most cost-effective strategy, but there was high uncertainty. The analysis was well conducted although some details were not presented. The authors’ conclusions are likely to be valid. Type of economic evaluation Study objective This study examined the cost-effectiveness of four different lifestyle interventions for patients aged 45 years or older with knee pain and a body mass index (BMI) of 28 or more. Interventions The four interventions were: dietary advice plus quadriceps strengthening exercises; dietary advice alone; quadriceps strengthening exercises alone; and leaflet provision. The dietary advice consisted of a personalised diet plan, which created a deficit of 600kcal a day. Quadriceps strengthening exercises were taught in groups and were then repeated at home daily. Methods Analytical approach:This economic analysis was based on a single study with a two-year time horizon. The authors stated that the analysis was carried out from the perspective of the UK National Health Service (NHS).
Effectiveness data:The clinical data came from a randomised controlled trial (RCT) that was published in an accompanying clinical paper. The study sample was enrolled from five general practices in the UK and included 109 participants in the dietary plus quadriceps strengthening intervention, 122 in the dietary intervention, 82 in the quadriceps strengthening intervention, and 76 in the leaflet intervention. The mean age of the sample was 61.3 years, 66% were women, and the length of follow-up was two years. The primary clinical outcome was the amount of knee pain, assessed using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC).
Monetary benefit and utility valuations:The utility valuations were derived from the sample of patients enrolled in the RCT using the European Quality of life (EQ-5D) questionnaire. These were estimated at baseline, six, 12 and 24 months and UK tariffs were used.
Measure of benefit:Quality-adjusted life-years (QALYs) were the summary benefit measure and a 3.5% discount rate was applied to those accrued over the second year.
Cost data:The economic analysis considered the costs of: visits (personnel time for travel and the home visit, and travel costs), materials (dyno bands for the strengthening exercise group), and analgesics. Visits to other health care professionals and hospitalisations were also assessed in a sub-sample of patients, but these were not included in the base-case analysis. The resource use data were derived directly from the RCT and missing data were replaced using a multiple imputation approach. The unit costs came from official NHS sources such as the Personal Social Services Research Unit and the Prescribing Support Unit of the Government Statistical Service. The unit costs and quantities of resources used were not presented separately. All costs were in UK pounds sterling (£) for the financial year 2006 to 2007. A 3.5% discount rate was applied to costs incurred in the second year.
Analysis of uncertainty:A probabilistic approach was used to generate cost-effectiveness acceptability curves. Confidence intervals (CIs) around the cost-utility ratios were calculated using the bootstrap technique. In an alternative scenario, it was assumed that patients in the leaflet arm incurred an initial visit, which was considered to be protocol-driven in the base case and thus excluded. Results The expected two-year gain in QALYs from baseline was 0.147 in the dietary plus strengthening exercise intervention, 0.133 in the dietary intervention, 0.090 in the strengthening exercise intervention, and 0.085 in the leaflet intervention.
The changes in costs were £615.64 for diet and exercise, £735.57 for diet, £214.66 for exercise, and -£31.07 for leaflets.
The incremental analysis showed that the diet alone was dominated by diet plus exercise. Exercise alone was not cost-effective as it was extendedly dominated, which means that the combination of leaflets with diet plus exercise could provide a higher benefit at equivalent cost. The incremental cost per QALY gained with diet plus exercise over leaflets was £10,469.44 (95% CI: 3,738.28 to dominated).
The cost-effectiveness acceptability curve showed that for threshold values of £30,000 or more per QALY, the probability of being cost-effective was less than 30% for all interventions. At a threshold value of £20,000 per QALY, the probability that diet plus exercise was the most cost-effective was 23.1%. When the cost of the initial visit was included, the leaflet strategy was dominated by exercise. Authors' conclusions The authors concluded that dietary advice plus strengthening exercises was the most cost-effective strategy, but there was high uncertainty. They also stated that further research should focus on the value of personalised knee pain interventions to improve adherence. CRD commentary Interventions:The selection of the comparators was based on the interventions in the RCT. These strategies were appropriate in the context of primary care. A description of the key features of each intervention was provided. The authors noted that a group exercise programme, which other studies had shown to be effective, was not considered to be relevant.
Effectiveness/benefits:The use of a RCT to derive the data on treatment effectiveness was appropriate as the RCT design is usually associated with high internal validity. The key features of the RCT were reported, but the full details were published in a companion paper. This prevents an exhaustive and comprehensive judgement of whether the clinical analysis was robust. The RCT enrolled a relatively large sample of patients, was carried out in several practices, and used a validated tool for the assessment of the clinical efficacy, which should enhance the validity of the clinical analysis. Some relevant details on the derivation of the utility valuations were provided. QALYs are a validated benefit measure, which capture the impact of the interventions on quality of life and survival (although survival was not relevant for this patient population), and they allow cross-disease comparisons to be made.
Costs:The analysis of costs included all the relevant categories of resources for the economic viewpoint of the third-party payer. Little information on the unit costs and resource quantities was given, which limits the transparency of the economic analysis. Other details on the price year, sources of data, and use of discounting were reported. In general, the authors justified their choice of the categories of costs. The sensitivity analysis considered the inclusion of the initial visit in the leaflet group.
Analysis and results:The analytic method used to combine the costs and benefits was appropriate since it allowed the exclusion of dominated strategies and identified the most cost-effective option. The findings were clearly presented and discussed. The issue of uncertainty was satisfactorily investigated in the sensitivity analysis, the key findings of which were important, as they showed the uncertainty underlying the selection of the most cost-effective strategy. The authors acknowledged that a longer time horizon would have been more appropriate. A potential justification was provided for the differences between the findings of this study and those of other studies.
Concluding remarks:The analysis was well conducted although some details were not presented. The authors’ conclusions are likely to be valid. Funding Funded by the UK Arthritis Research Campaign. Bibliographic details Barton G R, Sach T H, Jenkinson C, Doherty M, Avery A J, Muir K R. Lifestyle interventions for knee pain in overweight and obese adults aged >=45: economic evaluation of randomised controlled trial. BMJ 2009; 339:b2273 Other publications of related interest Jenkinson CM, Doherty M, Avery AJ, et al. Effects of dietary intervention and quadriceps strengthening exercises on pain and function in overweight people with knee pain: randomised controlled trial. BMJ 2009;339:b3170.
Thomas KS, Miller P, Doherty M, et al. Cost effectiveness of a two-year home exercise program for the treatment of knee pain. Arthritis Rheum 2005;53:388-94.
Hurley MV, Walsh NE, Mitchell HL, et al. Economic evaluation of a rehabilitation program integrating exercise, self-management, and active coping strategies for chronic knee pain. Arthritis Rheum 2007;57:1220-9. Indexing Status Subject indexing assigned by NLM MeSH Aged; Arthralgia /economics /prevention & Body Mass Index; Cost-Benefit Analysis; Exercise Therapy /economics; Humans; Knee Joint; Life Style; Middle Aged; Obesity /diet therapy /economics /rehabilitation; Overweight /diet therapy /economics /rehabilitation; Pamphlets; Patient Education as Topic; Quadriceps Muscle; Quality-Adjusted Life Years; Treatment Outcome; control AccessionNumber 22009102761 Date bibliographic record published 09/09/2009 Date abstract record published 21/10/2009 |
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