Cost-benefit analysis in screening. Unexplained visual loss

Cost-effectiveness analysis (CEA) and cost-benefit analysis (CBA) are accounting techniques that have been applied to medical decision-making. These techniques are applied here to two alternative diagnostic strategies in the work-up of patients with "unexplained visual loss." The first uses the results of visual field examination to decide if patients should have a CT scan ("visual field strategy"), the second bypasses visual fields and orders a CT scan on all patients ("CT strategy"). The analysis reveals that the visual field strategy is cost-effective only if perimetrists are able to identify hemianopic field defects in more than 80% of cases. It is doubtful that perimetrists are presently as accurate as that. These conclusions must be considered tentative since the epidemiologic data that support them are often weak. Another drawback in applying such an analysis to medical problem-solving is that costs may not accurately reflect patient valuations and choices. Nevertheless, in forcing a more comprehensive consideration of the effects of medical decisions, CEA/CBA is likely to promote increased cost-consciousness and epidemiologic research.