3 Key Takeaways
Plain English Summary- 01Core Finding
We measured associations of baseline body mass index (BMI), mid-upper arm circumference (MUAC), and premorbid BMI with spirometry, chest radiograph score, six-minute walk distance and St George's Respiratory Questionnaire score.
- 02Study Evidence
Tested in a observational cohort study (156 participants) at the real-world cohort stage.
- 03Practical Meaning
Observational cohort findings reveal real-world links, though lifestyle or unmeasured factors cannot be fully ruled out without an RCT.
What This Means for You
Undernutrition before and at treatment initiation is a potentially modifiable determinant of post-treatment lung impairment, with systemic inflammation mediating part of the effect. Nutritional assessment belongs in routine tuberculosis care, and nutritional support should be tested to prevent lung-function impairment in tuberculosis survivors.
The Discovery
Undernutrition is the leading driver of tuberculosis worldwide, yet its effect on the lungs of people who complete treatment is not well defined. Adults (≥18 years) with drug-sensitive pulmonary tuberculosis were enrolled at treatment initiation in India. We measured associations of baseline body mass index (BMI), mid-upper arm circumference (MUAC), and premorbid BMI with spirometry, chest radiograph score, six-minute walk distance and St George's Respiratory Questionnaire score. Plasma IFN-γ, TNF-α and IL-6 were measured at baseline and month 2; counterfactual mediation analysis partitioned the effect of undernutrition on lung function into direct and inflammation-mediated components. Of 156 participants analyzed, 76 (48.7%) had a ventilatory defect; 52 (33.3%) had airflow obstruction and 31 (19.9%) had restrictive spirometry. Each 1 kg/m 2 higher baseline BMI was associated with lower odds of any ventilatory defect (adjusted odds ratio [aOR], 0.78; 95% CI, 0.67-0.90), and BMI below 16 kg/m 2 carried five-fold higher odds than BMI ≥18.5 kg/m 2 (aOR, 5.08; 95% CI, 1.76-16.02). MUAC and premorbid BMI showed similar associations. Lower BMI was associated with restrictive spirometry (aOR, 0.74 per kg/m 2 ; 95% CI, 0.59-0.89) but not airflow obstruction (aOR, 0.91; 95% CI, 0.80-1.03). Undernourished participants had higher baseline IL-6, which mediated 32% (FEV1) and 49% (FVC) of the association with impaired lung function.
How It Works, Simply
This pulmonology research focuses on inflammation. Researchers evaluated it using an observational cohort study (156 participants) at the real-world cohort stage of medical research.
3 Key Takeaways
Clinical Takeaways- 01Core Finding
We measured associations of baseline body mass index (BMI), mid-upper arm circumference (MUAC), and premorbid BMI with spirometry, chest radiograph score, six-minute walk distance and St George's Respiratory Questionnaire score.
- 02Study Evidence
Tested in a observational cohort study (156 participants) at the real-world cohort stage.
- 03Practical Meaning
Observational cohort findings reveal real-world links, though lifestyle or unmeasured factors cannot be fully ruled out without an RCT.
Biological Mechanism & Study Design
Study Design & Cohort
Observational cohort study
Observational cohort study (156 participants) · Real-World Cohort
Biological Pathway & Modality
Inflammation
Intervention: The Impact of Undernutrition on Post-Tuberculosis Lung-Function: A Prospective
Experimental Findings & Endpoints
Undernutrition is the leading driver of tuberculosis worldwide, yet its effect on the lungs of people who complete treatment is not well defined.
Adults (≥18 years) with drug-sensitive pulmonary tuberculosis were enrolled at treatment initiation in India. We measured associations of baseline body mass index (BMI), mid-upper arm circumference (MUAC), and premorbid BMI with spirometry, chest radiograph score, six-minute walk distance and St George's Respiratory Questionnaire score.
Plasma IFN-γ, TNF-α and IL-6 were measured at baseline and month 2; counterfactual mediation analysis partitioned the effect of undernutrition on lung function into direct and inflammation-mediated components. Of 156 participants analyzed, 76 (48.7%) had a ventilatory defect; 52 (33.3%) had airflow obstruction and 31 (19.9%) had restrictive spirometry.
Each 1 kg/m 2 higher baseline BMI was associated with lower odds of any ventilatory defect (adjusted odds ratio [aOR], 0.78; 95% CI, 0.67-0.90), and BMI below 16 kg/m 2 carried five-fold higher odds than BMI ≥18.5 kg/m 2 (aOR, 5.08; 95% CI, 1.76-16.02). MUAC and premorbid BMI showed similar associations.
Lower BMI was associated with restrictive spirometry (aOR, 0.74 per kg/m 2 ; 95% CI, 0.59-0.89) but not airflow obstruction (aOR, 0.91; 95% CI, 0.80-1.03). Undernourished participants had higher baseline IL-6, which mediated 32% (FEV1) and 49% (FVC) of the association with impaired lung function.
Clinical Translation & Practice Context
Undernutrition before and at treatment initiation is a potentially modifiable determinant of post-treatment lung impairment, with systemic inflammation mediating part of the effect.
Nutritional assessment belongs in routine tuberculosis care, and nutritional support should be tested to prevent lung-function impairment in tuberculosis survivors.
The Bottom Line · Clinical Pearl
“Undernutrition before and at treatment initiation is a potentially modifiable determinant of post-treatment lung impairment, with systemic inflammation mediating part of the effect.”
Published in Chest · Current Stage: Real-World Cohort