Olfaction, body mass index, and quality of life with cystic fibrosis combination therapy

Background: Triple-combination therapy of elexacaftor-tezacaftor-ivacaftor (ETI) has been shown to reduce morbidity and mortality in people with cystic fibrosis (PwCF). Although patient body mass index (BMI) favorably increases with ETI treatment, factors contributing to this improvement are poorly characterized. Olfaction contributes to appetite stimulation and anticipation of eating, where higher rates of olfactory impairment (OI) in PwCF may contribute to malnutrition and BMI instability in this population.

Methods: The authors performed a prospective cohort study analyzing 41 CF patient responses to the Cystic Fibrosis Questionnaire-Revised (CFQR) and the 22-Item Sino-Nasal Outcome Test (SNOT-22) and used generalized estimating equations to understand the change in survey variables from being untreated (baseline) to undergoing 3 months of ETI therapy (follow-up).

Results: Patients reported significant improvement in their sense of smell at follow-up (p = 0.0036). Their improvements in sense of smell were not confounded by changes in rhinologic or extranasal rhinologic symptoms. Self-reported quality of life (QoL) improved after 3 months of ETI therapy (p = < 0.0001) as did BMI (p = < 0.0001), but improved sense of smell did not independently mediate these changes in QoL and BMI.

Conclusion: Our results support the impression that ETI therapy improves CF-associated rhinologic symptoms and reverses OI, while contributing to improvement in rhinologic QoL. Sense of smell is not an independent mediator of improved QoL and BMI in this population, suggesting that other factors may have a stronger role in these realms. However, given the subjective improvement in sense of smell, additional evaluation of OI using psychophysical chemosensory assessment will clarify the connection between olfaction, BMI, and QoL in PwCF.