Increased fat mass and obesity risk after elexacaftor-tezacaftor-ivacaftor therapy in young adults with cystic fibrosis

When people with cystic fibrosis (PwCFs) are treated with cystic fibrosis transmembrane conductance regulator protein modulator (CFTRm), it leads to changes in body composition. An easy, non-invasive, and reproducible method to assess this is by means of electrical bioimpedance measurement, which complements the information provided by the already-known anthropometric parameters. Seventeen adults with cystic fibrosis in treatment with elexacaftor-tezacaftor-ivacaftor (ETI) were recruited for a prospective, longitudinal, single-center study over 12 months. Study variables included weight, body mass index (BMI), and body composition by bioelectrical impedance analysis (BIA) [including fat mass (FM) and fat-free mass (FFM)]. At 12 months, there was an increase in overweight patients (5.9% vs. 23.5%) and a statistically significant increase in BMI at 6 and 12 months. An increase in FM and FFM was observed at 12 months. The increase was greater in FM (95% CI) from a baseline of 1.77% (0.00-3.54; = 0.050) at 6 months and 2.64% (0.48-4.81; = 0.020) at 12 months. After treatment with ETI, there was an increase in weight, BMI, and FM more than FFM in PwCF. These changes would be confirmed in long-term studies to improve nutritional management.