Sex differences in illness severity and mortality among adult intensive care patients: A systematic review and meta-analysis

PURPOSE: To investigate the association between sex and illness severity and mortality of ICU patients. METHODS: We performed systematic searches of MEDLINE and EMBASE for observational studies of adult ICU patients that explicitly examined the association between sex and illness severity or mortality. We used a random effects model to calculate standardised mean differences in illness severity scores and pooled odds ratios for mortality of women compared to men. RESULTS: We identified 21 studies with 505,138 participants in total (43.1% women). There was substantial heterogeneity among studies. Only two studies were at low risk of bias overall. At ICU admission, there was a pattern of higher illness severity scores among women (standardised mean difference 0.04, 95% CI -0.01-0.09). Women had higher risk-adjusted mortality than men at ICU discharge (OR 1.25 95% CI 1.03-1.50) and 1 year (OR 1.08, 95% CI 1.02-1.13), however this finding was not robust to sensitivity analysis. CONCLUSIONS: Women tend to have higher illness severity scores at ICU admission. Women also appear to have higher risk-adjusted mortality than men at ICU discharge and at 1 year. Given the heterogeneity and risk of bias in the existing literature, additional studies are needed to confirm or refute these findings.