Association between Sputum Culture Conversion and Body Mass Index among Multidrug-Resistant Tuberculosis Patients in Punjab, Pakistan: A Multicenter Retrospective Study.

Background: The global challenge of Multidrug-resistant Tuberculosis (MDR-TB) presents a substantial public health concern, requiring extended and complex treatment regimens. Understanding the factors impacting treatment results, particularly sputum culture conversion and Body Mass Index (BMI), is crucial. This retrospective cohort investigation conducted in Punjab, Pakistan, sought to explore the correlation between BMI and sputum culture conversion in individuals diagnosed with MDR-TB.

Material and methodology: Data from 2663 confirmed MDR-TB patients across multiple Programmatic Management of Drug-Resistant Tuberculosis PMDT sites in Punjab, Pakistan, were retrospectively analyzed. Demographic and clinical characteristics, BMI, comorbidities, previous TB treatments, and drug resistance were evaluated. Cox proportional hazards regression models were employed to assess the association between time to sputum culture conversion and patient characteristics.

Results: The study compared MDR-TB treatment outcomes based on BMI categories (≥18.5 vs. <18.5 Kg/m^2). It involved 1626 employed patients, with a mean age of 33 ± 15 years, displaying baseline body weights averaging 48±7 kg (normal weight) and 37±6 kg (underweight). On average, sputum culture conversion occurred at four months, with approximately 37% achieving conversion within this period. Among several factors studied, the univariate analysis identified BMI <18.5 Kg/m^2, prior firstline drug treatment, and comorbidities as significantly associated with failure to achieve sputum culture conversion within 6 months. In multivariate analysis, the inability to achieve conversion was notably linked to BMI <18.5 Kg/m^2, previous first-line drug treatment, and resistance to fluoroquinolone drugs.

Conclusion: This study provided valuable insights into sputum culture conversion, BMI, and drug resistance among MDR-TB patients. While around half of the patients achieved sputum culture conversion within six months, factors, such as comorbidities, previous TB treatment, and drug resistance, significantly influenced treatment outcomes.