The Association of Pretreatment Nutritional Status With Lung Function After Microbiologic Tuberculosis Cure

Abstract Rationale: Tuberculosis remains a public health tragedy with more than ten million people infected per year, majority of whom are from low and middle income settings. Malnutrition and HIV remain the leading risk factors for TB infection. Despite the advocacy and awareness about TB, post-TB morbidity and disability have been neglected by TB programs in Africa. We have previously showed that HIV-positive status is associated with preserved lung function at TB microbiologic cure, although the mechanisms are not clear. While supplemental feeding has showed an improvement in TB treatment outcomes, it is not known if undernutrition before treatment is associated with impaired lung function at TB cure. Methods: We prospectively enrolled patients with microbiologically confirmed drug-susceptible pulmonary TB at Mbarara University teaching hospital in Uganda from November 2021 to November 2023. Participants had no known prior lung disease and willing to be followed up for at least 18 months. We measured their pre-treatment clinical and sociodemographic characteristics. At TB cure, we assessed the pulmonary function using spirometry according to the ATS/ERS criteria. We calculated the percentage predicted forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) using the 2021 Global lung initiative race-neutral equations. We defined undernutrition as a body mass index (BMI) less than 18.5 kg/m2. We then fitted multivariate linear models to determine the association between pre-treatment undernutrition and lung function at TB cure. Results: We enrolled 189 participants of whom 137 participants were declared TB cured and eligible for lung function testing. Their average age was 41 years, 57 (42%) were HIV positive. 98 (72%) were men who were more underweight compared to females (56 (80%) versus 14 (20.0%), p=0.025. Underweight participants had lower mean percentage predicted FEV1 compared to those with normal nutritional state (62.8 vs 75.3%, p<0.001), and lower percentage predicted FVC (68.1 vs 78.14%, p = 0.002). On multivariate linear regression analysis adjusting for gender, age, HIV serostatus, and smoking, undernourished patients had a 9.03%, lower percentage predicted FEV1 (95% confidence interval -16.1 to -2.02%, p <0.001) and 8.3% lower percentage predicted FVC (95% confidence interval -15 to -1.6%, p <0.001). Conclusion: These findings suggest a significant relationship between pre-treatment nutritional status and lung function at microbiologic TB cure. Future studies on reducing the burden of PTLD may consider investigating nutritional interventions at the time of TB diagnosis.