The relationship between weight and pulmonary outcomes in overweight and obese people with cystic fibrosis: A retrospective observational study

Background A major focus in cystic fibrosis (CF) care aims to increase weight gain. Rates of overweight and obese people with CF have gradually increased over the past decade. Obesity could be a risk for restriction of lung volumes and airway obstruction as well as increase rates of pulmonary exacerbations in people with CF. Aim To assess the relationship between weight categories and pulmonary outcomes in children and adults with CF. Methods Patients 6 years of age and older were categorized into weight categories based on the Centers for Disease Control and Prevention (CDC) definitions. A retrospective chart review was conducted to obtain lung function testing and other outcomes. Results One hundred five patients with a median age of 20.6 years were included in this analysis. 8.4%, 64%, 18%, and 10% of patients were underweight, normal/healthy weight, overweight, and obese, respectively. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) (% predicted) did not differ between patients with weights in the normal range versus patients in the overweight/obese categories. Linear regression analysis showed a direct correlation between body mass index (BMI) and FEV1 that continued as BMI entered overweight and obese categories in both pediatric and adult patients. Overweight/obese patients did not have increased rates of pulmonary exacerbations compared to those in the normal/healthy weight category. Conclusion As CF therapies continue to improve, an increasing number of people with CF are exceeding the CDC's normal-weight range. Gaining weight past the normal range does not appear to negatively impact pulmonary health of people with CF. If this trend of increased weight gain continues, it remains to be seen if it will eventually negatively affect lung health.