This prospective, longitudinal study determined whether a frailty index (FI) could predict chemotherapy outcomes in a consecutive series sample of 175 patients with solid tumours aged ≥ 65 years.
The objectives were to:
1. Develop an FI derived from a comprehensive geriatric assessment (CGA) process.
2. Compare established FI cut-points of ≤ 0.25 and > 0.25 with:
a. Baseline assessments of fitness for chemotherapy derived from Vulnerable Elder’s Survey-13 (VES-13) and oncologists’ assessments, and prescribed chemotherapy.
b. Treatment outcomes (intra-treatment chemotherapy alterations, treatment completions, one-year survival).
Variables included baseline CGA, VES-13 and oncologists’ assessments, and longitudinal treatment outcomes (e.g. treatment changes, one-year survival). The total number of CGA deficits measured per patient was 42. The FI was determined as the number of deficits per patient divided by the number of deficits measured, to elicit a continuous measure (0.0 to 1.0) signifying extent of deficit accumulation and likely frailty. FI > 0.25 flags increasing frailty to the theoretical maximum of 1.0.
The FI could be calculated on all patients. The index had a right-skewed distribution with mean (SD) of 0.31 (0.14), and median (IQR) of 0.27 (0.21-0.39). The 99% limit to deficit accumulation was below the theoretical maximum of 1.0, at 0.75. FI was significantly related (p < 0.001) to vulnerability as assessed by VES-13 and doctors’ assessments of frailty. Baseline frailty was associated with treatment outcomes (Terminated, Completed, Not Planned) (p < 0.001). The “Not Planned” group were significantly frailer than the other two groups. Kaplan-Meier analysis indicated a trend for better cumulative survival in the < 0.25 group compared with the > 0.25 group.
The FI could contribute to oncogeriatric decision-making in the chemotherapy setting. The FI demonstrated good construct validity against the VES-13 and the treating oncologists’ assessments of fitness for treatment.