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

Background: 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.

Methods: 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)].

Results: 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.

Conclusion: 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.