Remaining underweight during Tuberculosis (TB) treatment is associated with a higher risk of unsuccessful TB treatment outcomes and relapse. Previous studies conducted in Ethiopia found that bodyweight not adjusted for height at the start of treatment is associated with poor treatment outcomes. However, the association of body mass index (BMI) and weight change during treatment with treatment outcomes has not been studied. We aimed to investigate the association of BMI at the time of diagnosis and after two months of treatment and TB treatment outcomes.
Using an ambi-directional cohort study design (retrospective and prospective), a total of 456 participants were enrolled among 30 randomly selected public health centers residing within six sub-cities of Addis Ababa, Ethiopia. Data were collected using medical chart abstraction and face to face interviews. We compared TB treatment outcomes in persons with a body mass index (BMI) <18.5kg/m2 (underweight) versus persons with BMI ≥18.5kg/m2 (normal or overweight) at treatment initiation and after two months of treatment. Treatment was classified as successful in persons who were free of symptoms and had a negative sputum smear for acid-fast bacilli at the end of the 6-month treatment course. We analysed outcomes using univariable and multivariable logistic regression with 95% CI and p value< 0.05.
Of enrolled study participants, 184 (40.4%) were underweight and 272 (59.6%) were normal or overweight. Body mass index (BMI ≥18.5kg/m2) at the start and second month of treatment were independent predictors for successful treatment outcome (AOR = 2.15; 95% CI: 1.05, 4.39) and (AOR = 3.55; 95% CI: 1.29, 9.73), respectively. The probability of treatment success among patients with BMI≥18.5kg/m2 at the start and second month of treatment was 92.9% and 97.1%, respectively versus 86.5% and 91.7% in patients with BMI<18.5kg/m2. Bodyweight not adjusted for height and change in the bodyweight after the second and sixth months of treatment were not significantly associated with treatment success.
In persons treated for TB disease, being underweight at baseline and after two months of treatment was a predictor for unsuccessful treatment outcomes. Nutritional assessment, counselling, and management are important components of TB treatment programs with the potential to improve treatment outcomes.