Nutrition and markers of disease severity in patients with bronchiectasis

Background: Increasing numbers of patients are being diagnosed with bronchiectasis, yet much remains to be elucidated about this heterogeneous patient population. We sought to determine the relationship between nutrition and health outcomes in non-cystic fibrosis (non-CF) bronchiectasis, using data from the U.S. Bronchiectasis Nontuberculous Mycobacterial Research Registry (U.S. BRR). Methods: This was a retrospective, observational, longitudinal study using 5-year follow-up data from the BRR. Bronchiectasis was confirmed on computed tomography (CT). We stratified patients into nutrition categories using body mass index (BMI), and correlated BMI to markers of disease severity. Results: Overall, n = 496 patients (mean age 64.6±13 years; 83.3% female) were included. At baseline 12.3% (n=61) were underweight (BMI<18.5kg/m2), 63.9% (n=317) had normal weight (BMI.18.5kg/m2 and <25.0kg/m2), 17.3% (n=86) were overweight (BMI.25.0kg/m2 and <30.0kg/m2), and 6.5% (n=32) were obese (BMI.30kg/m2). Men were overrepresented in the overweight and obese groups (25.6% and 43.8% respectively, p<0.0001). Underweight patients had lower lung function (forced expiratory volume in 1 second [FEV1] % predicted) than the other weight groups (64.5±22, versus 73.5±21, 68.5±20, and 76.5±21 in normal, overweight, and obese groups respectively, p=0.02). No significant differences were noted between BMI groups for other markers of disease severity at baseline, including exacerbation frequency or hospitalization rates. No significant differences were noted in BMI distribution between patients with and without Pseudomonas, nontuberculous mycobacteria, or by cause of bronchiectasis. The majority of patients demonstrated stable BMI over 5 years. Conclusions: Although underweight patients with bronchiectasis have lower lung function, lower BMI does not appear to relate to other markers of disease severity in this patient population.