Effect of malnutrition on tuberculosis microbiologic severity in India
The relationship between malnutrition and tuberculosis disease (TB) severity is understudied. This study analyzed data collected by a large cohort study to investigate the effect malnutrition, measured by BMI, had on TB mycobacterial burden. A study population of 538 subjects was utilized for this secondary data analysis. Multivariate negative binomial regression was used to evaluate relationships between body mass index (BMI) categories and mycobacterial growth indicator tube (MGIT) days to positive. Of the 538 subjects, 79% were male and 21% were female. The median age was 45 years of age. One subject was HIV seropositive and was excluded from the final analysis. There were incomplete outcome data for 63 subjects, who were excluded from the final analysis. BMI was categorized as severe malnutrition (BMI<16.5 kg/m2), malnutrition (16.5≤BMI<18.5), normal (18.5≤BMI<25), and overweight/obese (BMI≥25), with 27%, 32%, 36%, and 5% of the population comprising these categories, respectively. The median MGIT days to positive was 8 days. After adjusting for confounders, individuals who had severe malnutrition or malnutrition had an adjusted RR of 1.05 (95% CI, 0.90–1.23) and 1.08 (95% CI, 0.94, 1.24), neither measure was significant for the association between TB disease burden and MGIT. Overweight/obese individuals had an 8% decreased risk (RR=0.92, 95% CI, 0.79–1.19) of shorter time to result compared to those with normal BMI, after adjusting for confounders. The results of this study indicate that there is no significant association between BMI and MGIT in an adjusted model. However, there are several limitations to this result including, lack of cavitation data and failure to account for collinearity in the final model.