Multivariate model for predicting relapse in human brucellosis

Demographic, clinical, and laboratory data from 200 consecutive patients with acute brucellosis were analysed with univariate and multivariate methods to identify correlates of relapse. A risk score for predicting relapse was then calculated by using Cox proportional hazard model. The independent predictors of relapse were temperature of 38.3 degrees C or higher, positive blood cultures at baseline, and the duration of symptoms before treatment <10 days. Stratification according to the risk score demonstrated that rates of relapse were significantly different between risk groups (P<0.0001). The low-risk group had a 4.5% probability (6 of 135) of relapse at 12 months. In contrast, relapse was present in 15 of 47 patients in the medium-risk group (P<0.0017); and in 12 of 18 patients in the high-risk group (P<0.0001). This study provides a rational basis for estimating the risk of relapse in patients with acute brucellosis, and may be helpful in deciding what subjects might benefit from extra attention.