Association of undernutrition and tuberculosis outcomes: a retrospective multicentre cohort study in Italy.

OBJECTIVES: Undernutrition remains one of the most powerful yet neglected determinants of tuberculosis (TB) incidence and progression. While its impact on TB outcomes has been extensively described in low-income countries, limited evidence is available from high-income settings. This study aimed to assess the association between BMI strata at treatment initiation and TB-related outcomes in a large multicenter cohort from Italy. METHODS: ). Outcomes included time to sputum conversion, length of hospital stay, occurrence and severity of adverse events (AEs), incomplete treatment (including failure, death, and loss to follow-up), and loss to follow-up (LTFU). Multilevel regression models adjusting for study center and relevant confounders were used to assess associations between BMI strata and each outcome. RESULTS: ) showed higher rates of adverse events (54/74 [73.0%] vs 101/410 [24.6%]; adjusted odds ratio [aOR] 12.17, 95% CI 6.41-23.08), incomplete treatment (53/74 [71.6%] vs 87/410 [21.2%]; aOR 18.28, 95% CI 6.70-49.80), and loss to follow-up (41/74 [55.4%] vs 81/410 [19.7%]; aOR 5.99, 95% CI 2.58-13.90). Median hospital stay was also longer in this group (50 days [IQR 24-66] vs 30 days [IQR 18-60]), corresponding to a 23% adjusted increase. Weight gain during the first six months of treatment was not significantly associated with major outcomes. CONCLUSIONS: Severe underweight at treatment initiation is a major independent predictor of poor outcomes in TB. These findings highlight the need for systematic nutritional assessment and targeted interventions within TB programs, even in high-income, low-incidence settings.