Objective: To determine the utility of olfactory decline as a biomarker for frailty in Chronic Lung Disease (CLD).
Methods: Odor decline over 5 years (Rounds 2 and 3: R2, R3), an adapted Fried Frailty Index, and physician’s diagnosis of CLD were collected/constructed for 1,134 respondents in the National Social Life, Health and Aging Project, a prospective, nationally representative study of older US adults living at home. Developing frailty was defined as being robust/prefrail in R2 and frail in R3. Multivariate logistic regressions evaluated the association between odor decline, developing frailty, and CLD status. Interaction plots examined the effect of CLD on the relationship between odor decline and frailty.
Results: In individuals with CLD, odor decline over 5 years (R2 to R3) predicted frailty at the 5-year follow-up (R3) (OR=5.20, 95%CI=1.43-18.88, P=0.012); there was no such relationship in those without CLD. This differential association by CLD status was robust (interaction P=0.047). Furthermore, odor decline (R2 to R3) was associated with developing frailty across the same 5 year period in individuals with CLD (OR=9.05, 95%CI=2.12-38.62, P=0.003). These analyses were robust to thresholds for odor decline and frailty development and adjusted for patient demographics, comorbidities, alcohol, and cigarette use.
Conclusion: Older adults with CLD who experience odor decline over 5 years face higher odds of being frail compared to those who do not, independent of other risk factors. Use of odor decline as a biomarker to identify CLD patients who are more likely to become frail could allow us to institute pulmonary rehabilitation earlier and decrease adverse outcomes (mortality, exacerbations) that afflict these patients.