An index of self-rated health deficits in relation to frailty and adverse outcomes in older adults

Background and aims: Poor self-rated health is associated with adverse outcomes but its relationship with frailty is not completely understood. We examined how self-rated health (SRH) is related to health outcomes and how this relationship might differ by individual level of fitness or frailty in older people. Methods: In the Atlantic Canada sample of the Canadian Study of Health and Aging, individuals aged ≥65 (n=1318) completed a self-administered questionnaire, from which we constructed an index of self-rated health deficits (SRHDI). Heterogeneity in health status was evaluated (n=1260) by determining their Frailty Index (FI). Higher values on the FI indicate worse health status. We evaluated health attitudes in relation to other health markers and to mortality. Results: Comparing those with the lowest vs highest SRHDI, significant differences (p<0.001) were seen in the mean hospital admissions in the past year (0.2 (±0.02) vs 0.8 (±0.08)), 3MS cognitive score (85.0 (±0.5) vs 78.4 (±1.2)) and (p=0.003) for age (75.3 (±0.3) vs 77.1 (±0.6)). The SRHDI and FI were moderately correlated (r=0.49) and both predicted mortality. In the fittest older people, those with poor SRHDI had a significantly increased risk of death (OR=18, 95% CI 6.0-53.6); SRHDI did not affect mortality in those who were frail. Conclusions: Measuring SRH by an index of deficits is a valid construct and is associated with adverse health outcomes. The SRHDI may facilitate exploration of the complex relationships between illness burden and health outcomes in older people. When people are frail, worse health attitude does not seem to increase mortality, but in contrast, appears to increase mortality risk in fit older people.