Synergy between low BMI and hyperglycemia at baseline increases tuberculosis incidence among people living with HIV

Abstract

Objectives: Low BMI and hyperglycemia are each important risk factors for tuberculosis (TB). However, the contribution of synergy between low BMI and hyperglycemia to risk of TB among people living with HIV (PWH) is unexplored. We compared TB incidence among PWH with different exposure profiles to low BMI (BMI < 18.5 kg/m2) and hyperglycemia (random blood glucose ≥140 mg/dl).

Design and methods: We conducted a cohort study using data of PWH (≥15 years) who enrolled in Myanmar's Integrated HIV Care Program between 2011 and 2017. We used their follow-up data until 2018 to determine TB incidence.

Results: Among 20 865 PWH included in this study, 7610 (36%) had low BMI only, 1324 (6%) had hyperglycemia only, and 465 (2%) patients had concurrent low BMI and hyperglycemia (joint exposure) at baseline. During a median follow-up of 2.2 years (interquartile range: 0.5, 4.2), 3628 (17%) developed TB [6.7, 95% confidence interval (CI): 6.5,7.0 cases per 100 person-years (PY)]. TB incidence among PWH with joint exposure was 21.0 (95% CI: 18.0, 24.7), with low BMI only was 10.9 (95% CI: 10.4, 11.4), with hyperglycemia only was 5.2 (95% CI: 4.4, 6.3) and with no exposure was 4.6 (95% CI: 4.4, 4.9) cases per 100 PY. The attributable proportion of incident TB due to synergy between low BMI and hyperglycemia was 0.23 (95% CI: 0.06, 0.36).

Conclusion: Synergy between low BMI and hyperglycemia was associated with increased excess TB incidence in PWH. TB preventive treatment, nutritional support, and hyperglycemia management should be evaluated as interventions to reduce TB risk in PWH with joint exposure.