PREDICTION OF RELAPSE AFTER TREATMENT OF COCCIDIOIDOMYCOSIS

Relapse after apparently successful treatment of coccidioidomycosis ha s been a problem with both amphotericin B and the azoles. We conducted a retrospective cohort study of 34 patients who required therapy for coccidioidomycosis between 1973 and 1993; 10 relapsed and 25 (one pati ent received two courses of therapy) did not relapse during follow-up. The mean time to relapse after completion of therapy was 7.3 months ( range, 1-21 months). All 34 patients responded clinically to therapy, A fourfold or greater decrease in titers of antibody, as determined by complement fixation (CF), during therapy was seen in seven (78%) of n ine patients who relapsed and 17 (85%) of 20 patients who did not rela pse (P = .956), There was no significant difference between relapsers and nonrelapsers in terms of the lowest CF titer during therapy, the C F titer at the end of therapy, or the peak CF titer. The risk of relap se was increased among those with a peak CF titer of greater than or e qual to 1:256 (relative risk [RR] = 4.7; 95% confidence interval [CI] = 1.4-16.1), as compared with patients who did not mount such a high a ntibody response, Similarly, the risk of relapse was higher among thos e with serially negative coccidioidin skin tests (CSTs) than those wit h serially positive CSTs (RR = 4.8; 95% CI = 1.2-19.5). We conclude th at clinical response, lowest CF titer, end-of-therapy CF titer, and de crease in the CF titer of at least fourfold are not predictive of rela pse in patients with coccidioidomycosis. Negative serial coccidioidin skin tests and a peak CF antibody titer of greater than or equal to 1: 256 are independently associated with increased risk of relapse.