Cost-effectiveness of rapid latex agglutination testing and throat culture for streptococcal pharyngitis.

Decision analysis was used to evaluate the cost-effectiveness of four alternative strategies for management of pharyngitis in children ("treat all," "antigen test alone," "culture alone," "antigen test + culture"). In the model, estimates of test sensitivity and specificity, disease prevalence, treatment rates after positive test results, rates of complications for treated and untreated patient-cases, rates of antibiotic-induced complications, treatment effectiveness, and direct dollar costs of diagnosis and therapy were used. Results were expressed in terms of severe penicillin reactions per disease case prevented and dollars per complication prevented. Sensitivity analysis was performed to assess the impact of changes in parameter estimates on model outcomes. With treat all, 90% of streptococcal complications were prevented and there were low short-term direct dollar costs. However, treat all is associated with a high rate of penicillin allergy (70% of which occurs in uninfected children) and is the least cost-effective strategy when the costs of treating complications are included. The marginal cost of antigen test + culture is less than the cost of either one-test strategy. Antigen test + culture is the most cost-effective strategy when the costs of managing the complications of streptococcal infection are considered. Antigen test + culture is the most clinically effective strategy, and its benefits are obtained at a modest marginal cost relative to the one-test strategy.