COST-EFFECTIVENESS ANALYSIS OF PROPHYLACTIC PINNING OF THE CONTRALATERAL HIP FOLLOWING UNILATERAL SLIPPED CAPITAL FEMORAL EPIPHYSIS

Abstract

Slipped capital femoral epiphysis (SCFE) is the most common pediatric hip disorder. The most devastating complication is development of avascular necrosis of the femoral head. In order to reduce the potential for this complication occurring following delayed contralateral SCFE, there has been consideration in the literature of prophylactic pinning of the contralateral hip. The objective of this study was to determine the cost-effectiveness of this treatment strategy.

The outcome probabilities and utilities utilised in a decision analysis of prophylactic pinning of the contralateral hip in SCFE, reported by Kocher et al, were used in this study. Costing data, reported in 2005 Canadian dollars, was obtained from our institution. Using this data, an economic evaluation was performed. The time horizon was four years, so as to follow the adolescents to skeletal maturity. Discounting was performed at 3% per year. Sensitivity analyses were conducted to determine the effect of variation of the outcome probabilities and utilities.

In all analyses, prophylactic pinning resulted in cost savings but lower utility, compared to the currently accepted strategy of observation of the contralateral hip. The results were most sensitive to an increase in the probability of a delayed contralateral SCFE to 27%. Using the base case analysis, the incremental cost-effectiveness ratio was $7856.12 per utility gained. Using the most sensitive probability of a delayed contralateral SCFE of 27%, the incremental cost-effectiveness ratio was $27,252.92 per utility gained.

The results of this study demonstrated overall cost savings with prophylactic treatment, however the utility was lower than the standard treatment of observation. For both the base case and sensitivity analysis, the incremental cost-effectiveness ratio was less than the accepted threshold of $50,000 per quality adjusted life year gained. It should be noted that the use of a four year time horizon excluded consideration of the costs related to total hip arthroplasty for the sequelae of AVN. A prospective, randomised controlled trial, with an accompanying economic evaluation, is required to definitively answer the question of the cost-effectiveness of this treatment. On the basis of this cost-effectiveness analysis, prophylactic pinning of the contralateral hip in SCFE cannot be recommended. A prospective, randomised controlled trial, with an accompanying economic evaluation, is required to definitively answer the question of the cost-effectiveness of this treatment.