Global Poorer Olfaction, Frailty and Postoperative Adverse Outcomes: Exploring Their Interplay in a Prospective Cohort of Older Adults Undergoing Elective Surgery

Olfactory dysfunction has emerged as a marker of neurodegeneration and frailty in older adults, yet its value for perioperative risk stratification remains underexplored. This prospective study aimed to assess the interplay between three olfactory modalities (Threshold, Discrimination, Identification: TDI), baseline frailty, and postoperative outcomes in older patients undergoing surgery.

We enrolled adults aged 65 years or older scheduled for elective aortic/lower limb vascular or orthopedic procedures under general anesthesia. The day before surgery, patients underwent olfactory testing using the Sniffin' Sticks extended test (yielding a composite TDI score), and frailty evaluation with the Edmonton Frail Scale (EFS) and Clinical Frailty Scale. Postoperative moderate/severe complications or death occurring within one year were recorded. Statistical analyses included univariable and multivariable regression adjusted for age, sex, comorbidities, and surgical parameters.

From 362 screened patients, a final cohort of 209 patients (160 orthopedic, 49 vascular) was included after accounting for ineligibility, 42 refusals, and 6 data access exclusions. Lower olfactory performance (TDI score ≤ the 25^th percentile) was identified in 74 (35.4%) patients. Frailty (EFS ≥6/17) was present in 51 cases (24.4%). Frail patients had significantly lower TDI scores (median 25.25 vs 28.75, p<0.001), with all three modalities independently correlated with frailty after adjustment. Within one year, 54 (25.8%) experienced postoperative complications and 3 (1.4%) patients died. Reduced olfaction was associated with a higher risk of postoperative morbidity/mortality (39.2% vs 20.7%, p=0.004), and this association remained significant after accounting for age and gender, comorbidities, surgery type, and frailty. Lower olfactory performance, but not frailty, predicted poor outcomes in vascular patients (odds ratio 6.34, p=0.004), while only frailty was predictive in orthopedic patients.

Global poorer olfaction is closely associated with frailty and may serve as a robust indicator of adverse postoperative outcomes in older adults, beyond conventional frailty scales.