Frailty Index, Not Age, Predicts Treatment Outcomes and Adverse Events for Older Adults with Cancer.

Background: Frailty is an indicator of individual vulnerability and differentiates health status among people of the same chronological age.

Objectives: This study aimed to determine whether baseline frailty index (FI) was associated with systemic anticancer therapy treatment outcomes in older adults with solid cancers.

Design: Retrospective cohort study.

Setting: Major metropolitan outpatient oncology service.

Participants: Adults aged over 65 years with a solid malignancy who had been referred for consideration of systemic therapy, and had completed a baseline frailty assessment between January 2019 and July 2021.

Measurements: Frailty had been prospectively assessed with a 58-item FI derived from a geriatric oncology nurse assessment prior to initial oncologist appointments. Primary outcome was treatment completion, and secondary outcomes included incidence of high-grade treatment-related toxicity or unplanned hospital admissions, and survival outcomes. Univariate and multivariable regression analyses were conducted to test the association between treatment outcomes and baseline FI. Co-variates included age, sex, performance status, treatment intent, and stage. Kaplan-Meier and cox proportional hazard analysis were conducted for survival analysis.

Results: The median FI (IQR) was 0.24 (0.15-0.31) and 43% were frail (FI>0.25). FI was positively correlated with ECOG, however 28% of ECOG 0-1 were frail. In multivariable regression analyses, each 0.10 increase in FI was associated with an increased likelihood of not completing or not receiving treatment (OR 1.37, 95% CI 1.02-1.84; p=.04), treatment-related toxicity (OR 1.60, 95% CI 1.14-2.23; p<.01) and unplanned hospital admissions (OR 1.61; 95% CI 1.16-2.25; p<.01). Frail patients had increased mortality (adjusted HR 2.81, 95% CI 1.42-5.56; p<.01). Age did not predict treatment completion, toxicities, or survival.

Conclusion: Baseline FI is a granular measure that can help to identify frailer older patients who are more likely to require tailored therapy and support, and less frail older patients who are more likely to tolerate treatment.