Analytical approach:
A decision tree model was constructed to assess the cost-effectiveness of double-bundle anterior cruciate ligament reconstruction compared with single-bundle, in an otherwise-healthy young person with a reconstructed anterior cruciate ligament tear, over the 12 years after operation. The authors stated that a societal perspective was used.
Effectiveness data:
The clinical and effectiveness data were derived from published data or estimated by the authors, where published data were not available. The was reviewed to derive the estimates for probabilities of anterior cruciate ligament reconstruction failure (revision rates), which was the main measure of effectiveness. For double-bundle reconstruction, failure rates at four years were from a synthesis of 11 randomised controlled trials for single-bundle reconstruction identified by a review and considered to be the most unbiased level I studies of single-bundle anterior cruciate ligament reconstruction. For single-bundle reconstruction, failure rates were from two studies, with long-term follow-up. The percentages of patients with postoperative International Knee Documentation Committee (IKDC) outcomes were identified by a literature search.
Monetary benefit and utility valuations:
The utility values were derived, using a rating scale method, from a published survey of college student athletes and non-athletes. Expert opinion was used to correlate the states reported in the study with the IKDC grades A, B, C, and D (A was the best outcome).
Measure of benefit:
The measure of benefit was quality-adjusted life-years (QALYs) and these were discounted at an annual rate of 3%.
Cost data:
The direct health care costs included acute care hospitalisation, out-patient care, surgeon and anaesthesia fees, physical therapy, and durable medical equipment. All costs were from published studies. The indirect costs, such as productivity losses, were not included as they were assumed to be captured in the QALY outcome. All costs were reported in US dollars ($) for the year 2009 and discounted at an annual rate of 3%.
Analysis of uncertainty:
: One-way and multivariate sensitivity analyses were undertaken for model variables that included the cost of single-bundle repair, the marginal cost of a double-bundle repair, the utilities, the failure rates, the percentage of patients who experienced different IKDC grade outcomes, the discount rate, and the cost and outcomes of revision surgery. The results of the multivariate sensitivity analyses were presented graphically as the net monetary benefit for a willingness-to-pay threshold of $50,000 per QALY gained.