The impact of nutritional state on the duration of sputum positivity of Mycobacterium tuberculosis.

The outcome of anti-tuberculosis treatment varies according to patient factors.To retrospectively identify risks related to the extension of time to negative sputum culture (Tn) and to determine their clinical significance.Patients with bacilli susceptible to isoniazid and rifampicin who received initial standard treatment without cessation were recruited into the study. A total of 630 consecutive in-patients were included in the risk development analysis (development cohort) and another 611 consecutive in-patients in the risk validation analysis (validation cohort).Univariate analysis showed that Tn was related to sex, body mass index (BMI), white blood cell count (WBC), serum albumin, fasting blood sugar, haemoglobin A1c, C-reactive protein and total cholesterol levels and sputum smear positivity (SSP). Multivariate analysis showed that BMI, WBC and SSP were significant risk factors related to extended Tn. Optimal cut-offs of BMI and WBC for predicting good (Tn < 46 days) and poor responders (Tn ⩾ 46 days) according to each risk were determined by receiver operating characteristics analysis. Risks were verified with the validation cohort. Tn increased according to the number of risks; the median Tn for patients with three risks was 21 days longer than that of patients with none.The nutritional state of a TB patient can be used to predict Tn.