Higher body mass index associated with improved cystic fibrosis-related clinical outcomes

1. This systematic review and meta-analysis demonstrated that higher-than-normal body mass index (BMI) in patients with cystic fibrosis (CF) reduced the risk of CF-related complications, such as pulmonary function, pancreatic insufficiency, and CF-related diabetes.

2. Future guidelines should consider recommending higher BMI targets for patients with cystic fibrosis.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Cystic fibrosis (CF) is a common genetic condition associated with frequent airway infections, exocrine pancreatic insufficiency (PI), and CF-related diabetes (CFRD). Malnutrition is often found in patients with CF, and recent studies have demonstrated that malnourishment can worsen the progression of these CF-related complications. Body mass index (BMI) is a widely used measurement of nutritional status in CF patients. It is not clear whether higher-than-normal BMI is associated with improved clinical outcomes for patients with CF. This systematic review and meta-analysis investigated the association between BMI and clinical outcomes in patients with CF. The co-primary outcomes were pulmonary function (measured with FEV1%), PI, and CFRD. Sixty-one articles were included in the qualitative analysis, and 17 studies were included in the quantitative analysis. Compared to normal BMI patients, pulmonary function was significantly worse in underweight patients (weight mean differences [WMD]: 14.61% [95% CI: 10.39-18.83]) and better in overweight (WMD: -8.36% [95% CI: -12.74 to -3.97]) and obese (WMD: -12.06% [95% CI: -23.91 to -0.22]) patients. Furthermore, normal BMI patients demonstrated lower odds of PI compared to those who were underweight (odds ratio [OR]: 0.45 [95% CI: 0.27-0.77]) and higher odds of PI compared to overweight (OR: 4.4 [95% CI: 3.00-6.45]) and obese (OR: 10.88 [95% CI: 4.58-25.85]) patients. CFRD rates were statistically similar between underweight and normal BMI patients, but significantly more common in normal BMI patients than overweight ones (OR: 1.49 [95% CI: 1.10-2.00]). Overall, this study demonstrated that higher BMI in patients with CF is associated with a reduced risk of CF-related complications. It is notable to consider the heterogeneity of patients in this study and weigh the well-known long-term complications associated with obesity when incorporating these results into clinical practice.

Click to read the study in JAMA Network Open

Click to read an accompanying editorial in JAMA Network Open

Relevant Reading: Better nutritional status in early childhood is associated with improved clinical outcomes and survival in patients with cystic fibrosis

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