Objective: To assess the safety of discontinuing prophylaxis with antimicrobial agents in patients judged to be at relatively low risk for recurrence of acute rheumatic fever.
Design: Observational cohort study.
Setting: Public health clinics in the Southeast Health District of Santiago, Chile.
Patients: Fifty-nine patients (19 men, 40 women) ranging in age at study entry from 15 to 44 years (mean, 24.5 years). Forty-eight had completed their prescribed period of prophylaxis. Eleven refused or were allergic to intramuscular benzathine penicillin G and were noncompliant with oral sulfadiazine.
Intervention: In patients who did not have carditis during their previous attack(s), prophylaxis was discontinued after 5 years or at age 18, whichever was longer. In those with only mild mitral regurgitation or healed carditis, prophylaxis was stopped after 10 years or at age 25. Symptomatic intercurrent streptococcal throat infections were treated with antibiotics.
Measurements: Patients were seen every 3 months during the study (July 1982 to September 1988). For the first 4.25 years, throat cultures as well as sera samples for antistreptolysin O and anti-DNAse B assays were obtained at each visit.
Results: During laboratory surveillance, significant increases in antibody titers were detected in 56 instances (28.1 [95% CI, 21.7 to 36.5] per 100 patient-years), and 29 isolations of group A streptococci occurred (14.5 [CI, 10.1 to 20.8] per 100 patient-years). The patients were followed for a total of 3349 patient-months, during which time two acute rheumatic fever recurrences were observed (0.7 [CI, 0.2 to 2.6] per 100 patient-years). No recurrences occurred during an outbreak of acute rheumatic fever in 52 patients in the study area in 1986.
Conclusions: These and other data indicate that acute rheumatic fever prophylaxis can safely be discontinued in young adults judged to be at low risk for recurrence and who are maintained under careful prospective surveillance.