Background: Resting metabolic rate (RMR) is increased in people with CF (PWCF). However the reasons for this are poorly understood. A result of increased RMR is malnutrition which, in CF, is associated with poorer lung function. The prognosis for PWCF has improved due in part to more aggressive treatment and the introduction of new drugs such as Kalydeco.
Objective: To assess the parameters influencing RMR, lung function and nutritional status in PWCF; and to examine the impact of Kalydeco on outcomes in PWCF with the G551D mutation.
Design: RMR was measured by indirect calorimetry on 46 PWCF aged 6.8-17.1 years. Additional parameters collected at this time point included lung function and anthropometry.
Outcomes: Mean RMR was 112% of predicted. Mean BMI was on the 44.4th centile and mean FEV1 was 86.7%. There were no statistically significant associations between any of the parameters assessed and RMR. A significant positive association was found between BMI and FEV1 (r= 0.347, P= 0.010). Those with a PEG inserted were found to have a significantly lower BMI centile (30th vs. 51st, P= 0.011) and FEV1 (69% vs. 95%, P=0.001) than those without a PEG. This difference in FEV1 persisted after controlling for BMI. Five patients were taking Kalydeco and they had a significantly higher FEV1 than those not taking the drug (110% vs. 84%, P=0.037). A trend toward improvement was observed in all other parameters assessed in relation to Kalydeco, with the exception of height centile.
Conclusion: The study group appear to be maintaining good growth and lung function. The introduction of Kalydeco appears to be of significant benefit to those with the G551D mutation. An increase in RMR was observed as expected, however the parameters affecting RMR remain poorly understood.
Funding source: N/A