Association between frailty and clinical outcomes (all-cause mortality and hospitalisation)
| Frailty level | N | All-cause mortality | Unscheduled hospitalisation | ||||||
| Events (N) | Model 1 HR (95% CI) | Model 2 HR (95% CI) | Model 3 HR (95% CI) | Events (N) | Model 1 IRR (95% CI) | Model 2 IRR (95% CI) | Model 3 IRR (95% CI) | ||
| SERA: Frailty index (three levels)* | |||||||||
| Robust | 303 | 8 | ref | ref | ref | 152 | ref | ref | ref |
| Mild | 487 | 28 | 1.83 (0.83 to 4.02) | 1.74 (0.79 to 4.29) | 1.73 (0.7 to 4.29) | 416 | 1.55 (1.17 to 2.64) | 1.47 (1.12 to 1.94) | 1.29 (0.93 to 1.77) |
| Moderate/severe | 109 | 17 | 3.99 (1.7 to 9.35) | 4.41 (1.85 to 10.49) | 4.14 (1.49 to 11.51) | 189 | 3.05 (2.09 to 4.47) | 2.88 (1.97 to 4.20) | 2.27 (1.45 to 3.57) |
| UK Biobank: Frailty index (three levels)* | |||||||||
| Robust | 773 | 79 | ref | ref | 618 | ref | ref | ||
| Mild | 2001 | 279 | 1.39 (1.08 to 1.79) | 1.36 (1.05 to 1.76) | 2520 | 1.68 (1.44 to 1.97) | 1.65 (1.41 to 1.93) | ||
| Moderate/severe | 823 | 158 | 1.84 (1.4 to 2.43) | 1.68 (1.26 to 2.13) | 1827 | 3.13 (2.62 to 3.74) | 2.74 (2.29 to 3.29) | ||
| UK Biobank: Frailty index (four levels) | |||||||||
| Robust | 773 | 79 | ref | ref | 618 | ref | ref | ||
| Mild | 2001 | 279 | 1.39 (1.09 to 1.79) | 1.36 (1.05 to 1.76) | 2520 | 1.64 (1.41 to 1.92) | 1.65 (1.41 to 1.93) | ||
| Moderate | 714 | 130 | 1.73 (1.3 to 2.3) | 1.59 (1.19 to 2.13) | 1443 | 2.54 (2.11 to 3.05) | 2.47 (2.05 to 2.98) | ||
| Severe | 109 | 28 | 2.75 (1.78 to 4.27) | 2.33 (1.49 to 3.64) | 384 | 5 (3.58 to 6.99) | 4.8 (3.43 to 6.73) | ||
| UK Biobank: Frailty phenotype | |||||||||
| Robust | 788 | 68 | ref | ref | 630 | ref | ref | ||
| Prefrail | 1775 | 224 | 1.45 (1.11 to 1.91) | 1.37 (1.04 to 1.81) | 2209 | 1.57 (1.34 to 1.84) | 1.52 (1.29 to 1.78) | ||
| Frail | 781 | 158 | 2.54 (1.9 to 3.93) | 2.30 (1.71 to 3.10) | 1486 | 2.47 (2.07 to 2.99) | 2.38 (1.97 to 2.87) | ||
Model 1: adjusted for age, sex and socioeconomic status.
Model 2: adjusted for age, sex, socioeconomic status, smoking and alcohol intake.
Model 3: adjusted for age, sex, socioeconomic status, smoking, alcohol intake and DAS28 (SERA only).
*Due to the small number of SERA participants in the severe frailty category (0.2%) these were collapsed into moderate/severe for analysis of SERA. For UK Biobank, the frailty index was analysed using 4-levels (robust, mild, moderate, severe) as prespecified and then using 3-levels (robust, mild, moderate/severe) to mirror the analysis of SERA.
.DAS28, Disease Activity Score in 28 joints; IRR, incidence rate ratio; SERA, Scottish Early Rheumatoid Arthritis.