The Hospital Frailty Risk Score showed fair overlap with dichotomised Fried and Rockwood scales (kappa scores 0♲2, 95% CI 0♱5–0♳0 and 0♳0, 0♲2–0♳8, respectively) and moderate agreement with the Rockwood Frailty Index (Pearson's correlation coefficient 0♴1, 95% CI 0♳8–0♴7). The c statistics (ie, model discrimination) between individuals for these three outcomes were 0♶0, 0♶8, and 0♵6, respectively.

In the national validation cohort (n=1 013 590), compared with the 429 762 (42♴%) patients with the lowest risk scores, the 202 718 (20♰%) patients with the highest Hospital Frailty Risk Scores had increased odds of 30-day mortality (odds ratio 1♷1, 95% CI 1♶8–1♷5), long hospital stay (6♰3, 5♹2–6♱0), and 30-day readmission (1♴8, 1♴6–1♵0). In the development cohort (n=22 139), older people with frailty diagnoses formed a distinct group and had higher non-elective hospital use (33♶ bed-days over 2 years compared with 23♰ bed-days for the group with the next highest number of bed-days).

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