Background: Increased cancer incidence and frailty are both associated with advancing age. While geriatric assessments have been shown to improve outcomes, routine clinical implementation is limited by the resources required. We therefore aimed to develop and validate an electronic frailty index (eFI) to automatically categorise frailty using available administrative data.
Methods: The study utilised data from the Queensland Oncology Repository, which links the population-based Queensland Cancer Register to hospital admission records. Eligible patients were aged ≥70 years, diagnosed with any invasive cancer between 2019-2023 and had at least one hospital admission. An eFI was constructed from 40 health deficits mapped from ICD-10 admission codes from 2016 onward, with scores ranging from 0 to 1. All-cause survival to 31 December 2024 was estimated using the Kaplan-Meier method, and optimal clinical risk stratification was determined from K-median clustering.
Results: Of 73,024 potentially eligible patients, 66,606 (91%) met the inclusion criteria (61% male; median age 77 years). The median eFI score was 0.100 (IQR 0.050–0.175). Mean eFI scores increased steadily with age and were slightly higher in females. A strong inverse relationship was observed between eFI scores and survival. Five-year survival varied from 68% for patients with no deficits (eFI=0.000) to 9% among those with 12 or more deficits (eFI>=0.300). K-median clustering identified five distinct survival trajectories, classified as "fit" (eFI 0.000-0.025), "vulnerable" (0.026-0.075), "mildly frail" (0.076-0.150), "moderately frail" (0.151-0.299), and "severely frail" (>=0.300).
Conclusion: The eFI provides automated and real-time categorisation regarding a patient’s likely chances of survival, thereby assisting clinicians with appropriate treatment choices for older people with cancer. Possible next steps will be to compare correlation of the eFI against a clinical frailty index for the same patients and to evaluate its suitability for specific types of cancer.