The male-female health-survival paradox in hospitalised older adults

Abstract

Objectives: To determine whether the 'male-female health-survival paradox' is present in older hospitalised adults and to examine whether sex differences in the 'lethality' of acute medical conditions influence the relationship between sex and mortality.

Study design and outcome measures: This study was a secondary analysis of prospective cohort data collected from 1418 Australian inpatients aged 70 years and over. Frailty was measured using a 39-variable Frailty Index (FI-AC). Analyses examined the relationship between sex, age, FI-AC and 28-day mortality. Survival models were adjusted for 'lethality' of acute conditions (high versus low mortality risk).

Results: The FI-AC had a normal distribution in both sexes (female mean=0.34 (±0.13); male mean=0.31 (±0.15)). When adjusted for age, females had similar FI-AC scores to males (β coefficient=0.014, 95% confidence interval (CI)=0.00-0.028, p=0.056). There were 80 deaths in the sample, with females facing a significantly lower mortality risk than males of the same FI-AC and age (HR=0.39, 95% CI=0.25-0.63, p<0.001). Females were less likely than males to be admitted with a high-risk acute condition. Even so, this did not significantly reduce their survival advantage (HR=0.46, 95% CI=0.29-0.73, p=0.001).

Conclusion: The male-female health-survival paradox was not demonstrated in this study of older inpatients. Whilst females faced a significantly lower risk of near-term mortality, the sexes were found to have similar levels of frailty on admission to hospital. The sex mortality gap was not explained by sex differences in the 'lethality' of acute medical conditions.

Keywords: Frailty; Frailty index; Hospitalisation; Inpatient; Sex differences.