Ocular toxoplasmosis in immunocompetent adults: current cost-effectiveness of four treatment regimens in Colombia

Background: Ocular toxoplasmosis is an infection caused by Toxoplasma gondii. In South America, the clinical course of ocular toxoplasmosis is more severe than in Europe and North America because virulent strains of the parasite are present. Ocular toxoplasmosis is the leading cause of posterior uveitis and retinochoroiditis in Colombia, requiring timely and appropriate treatment. However, there is no standardized therapy protocol based on economic studies for the country. Purpose: To compare the cost-effectiveness of four first-line treatment regimens for active ocular toxoplasmosis in immunocompetent adults in Colombia, using the number of averted therapeutic failures as the outcome. Methods: We performed an economic and cost-effectiveness analysis to compare four first-line treatment regimens for ocular toxoplasmosis from the perspective of a third-party payer (Colombian General System of Social Security in Health). A decision analysis tree was used over a 24-week time horizon, considering only direct costs. Additionally, we performed a discrete sensitivity analysis and a probabilistic sensitivity analysis with 10,000 iterations in the Monte Carlo simulation. Results: For the base case, trimethoprim/sulfamethoxazole showed 86% effectiveness at a cost of <57 United States Dollars, resulting in the most cost-effective first-line alternative. When performing the probabilistic sensitivity analysis and maintaining the willingness to pay 466.00 United States Dollars, the trimethoprim/sulfamethoxazole regimen remained the most cost-effective alternative. Conclusion: Ocular toxoplasmosis is a public health issue in Latin America. Despite severe visual consequences for affected patients, there are no standardized treatment guidelines in countries such as Colombia. Our evidence supports the use of trimethoprim/sulfamethoxazole as first-line treatment in Colombia because of its availability and optimal cost-effectiveness performance; it reduces recurrences and complications, while averting therapeutic failure. Furthermore, our evidence can be generalized to other Latin American countries with similar frequencies and severities of Toxoplasma gondii ocular infection and health systems similar to the Colombian system.