Trimethoprim-Sulfamethoxazole Versus Placebo in Reducing the Risk of Toxoplasmic Retinochoroiditis Recurrences: A Three-Year Follow-up

Abstract

To compare the effects of 1 year of treatment with trimethoprim/sulfamethoxazole (TMP-SMZ) vs a placebo in reducing the risk of toxoplasmic retinochoroiditis recurrences during a 3-year follow-up period. Randomized, double-masked clinical trial. This cohort included 141 volunteers recruited in Campinas, Brazil. Inclusion criterion was unilateral active recurrent toxoplasmic retinochoroiditis. All volunteers were treated with 1 tablet of TMP-SMZ (160 mg/800 mg) twice daily for 45days, and all lesions healed after this treatment. After this initial treatment, the volunteers were randomly assigned to Group 1(1TMP-SMZ tablet every 2days for 311days) or Group 2 (1 identical placebo tablet containing starch with no active ingredients every 2days for 311days). At the second- and third-year follow-up appointments, none of the volunteers received treatment unless a new recurrence episode had occurred. The primary outcomes were recurrent toxoplasmic retinochoroiditis within the first year of follow-up and recurrent toxoplasmic retinochoroiditis within the third year of follow-up. The cumulative probability of recurrence at 1, 2, and 3 years of follow-up were, respectively, 13.0% (9/69), 17.4% (12/69), and 20.3% (14/69) in the placebo group and 0% (0/72) in the TMP-SMZ group (P < .001, log-rank test). There was no case of multiple recurrences in the same individual. No treatment-limiting toxicity or side effects were observed in either group. New recurrences were more frequent among female volunteers. TMP-SMZ may be used safely for prophylaxis of recurrent toxoplasmic retinochoroiditis, with long-term benefits.