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A cost-effectiveness analysis of total hip arthroplasty for osteoarthritis of the hip |
Chang R W, Pellissier J M, Hazen G B |
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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. Health technology Total hip arthroplasty (THA) for the osteoarthritis of the hip.
Economic study type Cost-effectiveness analysis.
Study population Persons with functionally significant hip osteoarthritis.
Setting Hospital. The economic study was conducted in Chicago, USA.
Dates to which data relate Effectiveness data related to studies published after 1986 (although relevant studies published before this date were also included); costs data related to 1990 and 1992.
Source of effectiveness data Effectiveness data was taken from a review of previously completed studies.
Modelling Decision analytic models of the THA and nonoperative strategies were constructed using the factored stochastic tree method described by Hazen. Stochastic trees resemble decision trees in that chance nodes and decision nodes are incorporated. However, branches can represent not only instantaneous probabilistic events, such as the result of a THA or perioperative death, but also competing risks that can occur over the course of time, such as aseptic loosening, prosthetic infection, and death form other causes.
Outcomes assessed in the review Probabilities and rates required by the model were calculated based on efficacy of primary and revision THA, operative mortality, long-term infection failure rates, long-term aseptic failure rates, and natural progression of functional class III osteoarthritis.
Study designs and other criteria for inclusion in the review Studies were include if their publication date was after 1986 (although relevant studies published before this date were also included) and if they used outcome measures and provided enough follow-up data to allow for the estimation of the probabilities and rates needed for the analyses.
Sources searched to identify primary studies The literature was identified by searching MEDLINE.
Criteria used to ensure the validity of primary studies Whether the study used outcome measures and provided enough follow-up data to allow for the estimation of the probabilities and rates needed for the analyses.
Methods used to judge relevance and validity, and for extracting data Whether the study used outcome measures and provided enough follow-up data to allow for the estimation of the probabilities and rates needed for the analyses.
Number of primary studies included 25 studies were included in the review.
Methods of combining primary studies Investigation of differences between primary studies Results of the review Functional outcome was considered the primary measure of effectiveness for THA. For modelling purposes, the authors adapted the four-state American College of Rheumatology (ACR) status classification for use in hip osteoarthritis, ranging from class I - complete ability to carry on all usual duties without handicaps, to class IV - incapacitated. The goal of the decision analytic model was to estimate expected times in each ACR functional class.
Measure of benefits used in the economic analysis The functional classes detailed in the four-state ACR classification were assigned utility values to allow the relative effectiveness of THA to be expressed in quality-adjusted life years (QALYs).
Direct costs Direct health service costs were considered, such as: THA hospital costs, recurring medical costs for functionally significant hip osteoarthritis and for custodial care. THA hospital cost data were obtained from local teaching hospitals' cost accounting systems. Recurring medical cost data were derived from the literature. Costs were discounted at 3%.
Statistical analysis of costs Sensitivity analysis Although not explicitly stated as sensitivity analysis, the authors made calculations for two scenarios: base-case and worst case.
Estimated benefits used in the economic analysis The incremental quality-adjusted life years (QALYs) gained were estimated to be between 0.52 and 6.88 depending on gender and scenarios. QALYs were discounted by 3% per year.
Cost results In the base-case scenario for 60-year-old white women who have functionally significant, but not dependent, hip osteoarthritis, the model predicts that THA is cost-saving because of the high costs of custodial care associated with dependency due to worsening hip osteoarthritis. In the base-case scenario for men aged 85 years and older, the average life time cost associated with THA is $9100 more than for non-operative management.
Synthesis of costs and benefits The incremental cost-effectiveness ratio of THA vs no THA varied between $17,115 and $79,029 per QALY depending on gender and scenarios. The THA cost-effectiveness ratio increases with age and is higher for men than women. In the base-case scenario for 60-year-old white women who have functionally significant, but not dependent, hip osteoarthritis, the model predicts that THA is cost-saving because of the high costs of custodial care associated with dependency due to worsening hip osteoarthritis and that the procedure increases QALE by about 6.9 years.
In the base-case scenario for men aged 85 years and older, the average life time cost associated with THA is $9100 more than non-operative management, with an average increase in QALE of about 2 years. Thus, the THA cost-effectiveness ratio for men aged 85 years and older is $4600 per QALY gained, less than that of procedures such as coronary artery bypass surgery or renal dialysis. Worst-case analysis suggests that THA remains minimally cost-effective for this oldest age category ($80000/QALY).
Authors' conclusions For persons with hip osteoarthritis associated with significant functional limitation, THA can be cost saving, or, at worst, cost-effective in improving QALE when both short- and long-term outcomes are considered.
CRD Commentary This was an interesting and complex modelling exercise that manages to comply with almost all the requirementsof a quality cost-effectiveness analysis.
Implications of the study Further research is needed to determine whether this procedure is actually being used in this cost-effective manner, especially in older age groups.
Source of funding The study was supported by National Institutes of Health, National Institute of Arthritis, Musculoskeletal, and Skin Diseases Multipurpose Arthritis and Musculoskeletal Diseases grant, National Science Foundation grant, and a grant form the Arthritis Foundation.
Bibliographic details Chang R W, Pellissier J M, Hazen G B. A cost-effectiveness analysis of total hip arthroplasty for osteoarthritis of the hip. Journal of the American Medical Association 1996; 275(11): 858-865 Indexing Status Subject indexing assigned by NLM MeSH Age Factors; Aged; Aged, 80 and over; Cost-Benefit Analysis; Data Collection; Decision Trees; Disease Progression; Female; Hip Prosthesis /economics /mortality; Humans; Male; Middle Aged; Models, Economic; Osteoarthritis, Hip /economics /physiopathology /surgery; Probability; Prosthesis Failure; Quality-Adjusted Life Years; Reoperation /economics /mortality; Sex Factors; Stochastic Processes; United States /epidemiology; Value of Life AccessionNumber 21996008079 Date bibliographic record published 31/03/1998 Date abstract record published 31/03/1998 |
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