Lack of Weight Gain and Relapse Risk in a Large Tuberculosis Treatment Trial

Abstract Background Readily identified markers of tuberculosis relapse risk are needed, particularly in resource-limited settings. The association between weight gain or loss during antituberculosis therapy and relapse has not been well studied. Methods Subjects in the Tuberculosis Trials Consortium Study 22 were studied. Underweight was defined as 10% or more below ideal body weight at diagnosis. Weight change was assessed between (1) diagnosis and completion of induction phase therapy, (2) diagnosis and end of continuation phase therapy, and (3) completion of induction to completion of continuation phase therapy. Results A total of 857 subjects were monitored for 2 yr, and 61 of 857 (7.1%) relapsed. Relapse risk was high among persons who were underweight at diagnosis (19.1 vs. 4.8%; p 0.001) or who had a body mass index of less than 18.5 kg/m2 (19.5 vs. 5.8%; p 0.001). Among persons who were underweight at diagnosis, weight gain of 5% or less between diagnosis and completion of 2-mo intensive phase therapy was moderately associated with an increased relapse risk (18.4 vs. 10.3%; relative risk, 1.79, 95% confidence interval, 0.96–3.32; p = 0.06). In a multivariate logistic regression model that was adjusted for other risk factors, a weight gain of 5% or less between diagnosis and completion of 2-mo intensive phase therapy among persons underweight at diagnosis was significantly associated with relapse risk (odds ratio, 2.4; p = 0.03). Conclusions Among persons underweight at diagnosis, weight gain of 5% or less during the first 2 mo of treatment is associated with an increased relapse risk. Such high-risk patients can be easily identified, even in resource-poor settings. Additional studies are warranted to identify interventions to decrease risk of relapse in such patients.