Sex differences in long-term survival after intensive care unit treatment for sepsis: A cohort study

Epidemiology of Intensive Care Patients Classified as a Third Sex in Australia and New Zealand

BACKGROUND

Patient sex affects treatment and outcomes in critical illness. Previous studies of sex differences in critical illness compared female and male patients. In this study, we describe the group of patients classified as a third sex admitted to ICUs in Australia and New Zealand.

RESEARCH QUESTION

What are the admission characteristics and outcomes of ICU patients classified as belonging to a third sex group compared with patients classified as female or male?

STUDY DESIGN AND METHODS

Retrospective observational study of admissions to 200 ICUs, recorded in the Australian and New Zealand Intensive Care Society's Adult Patient Database from 2018 to 2022. We undertook mixed effect logistic regression to compare hospital mortality across the sex groups, adjusted for illness severity, diagnosis, treatment limitation, year, and hospital.

RESULTS

We examined 892,161 admissions, of whom 525 (0.06%) were classified as third sex. Patients classified as third sex were represented across all diagnostic categories, jurisdictions, and hospital types. On average, they were younger than the groups classified as female (59.2 ± 20.0 vs 61.3 ± 18.4 years; P = .02) or male (63.2 ± 16.7 years; P < .001), respectively. Patients classified as third sex were more likely to be admitted after orthopedic surgery (10.1% third sex admissions [95% CI, 7.7%-13.0%]; 6.2% female [95% CI, 6.1%-6.3%]; 4.8% male [95% CI, 4.7%-4.9%]) and drug overdose (8.8% third sex admissions [95% CI, 6.5%-11.5%]; 4.2% female [95% CI, 4.1%-4.2%]; 3.1% male [95% CI, 3.0%-3.1%]). There was no difference in the adjusted hospital mortality of patients classified as third sex compared with the other groups.

INTERPRETATION

Patients classified as third sex composed a small minority group of adult ICU patients. This group had a different diagnostic case mix but similar outcomes to the groups classified as female or male. Further characterizing a third sex group will require improved processes for recording sex and gender in health records.

Estrogen receptor subtype mediated anti-inflammation and vasorelaxation via genomic and nongenomic actions in septic mice

Aim

Sepsis is a life-threatening disease with high mortality worldwide. Septic females have lower severity and mortality than the males, suggesting estrogen exerts a protective action, but nothing is known about the role of vascular endothelial estrogen receptor subtypes in this process. In the present study, we aimed to study the estrogen receptors on mesenteric arterioles in normal and sepsis mice and to elucidate the underlying mechanisms.

Methods

Sepsis was induced in mice by intraperitoneal injection of LPS. The changes in the expression and release of the serum and cell supernatant proinflammatory cytokines, including TNF-α, IL-1β and IL-6, were measured by qPCR and ELISA, and the functions of multiple organs were analyzed. The functional activities of mouse mesenteric arterioles were determined by a Mulvany-style wire myograph. The expression of phospholipase C (PLC) and inositol 1,4,5-trisphosphate receptor (IP₃R) in endothelial cells were examined by Western blot and their functions were characterized by cell Ca²⁺ imaging.

Results

Septic female mice had higher survival rate than the male mice, and pretreatment with E₂ for 5 days significantly improved the survival rate and inhibited proinflammatory cytokines in septic male mice. E₂ ameliorated pulmonary, intestinal, hepatic and renal multiple organ injuries in septic male mice; and ER subtypes inhibited proinflammatory cytokines in endothelial cells via PLC/IP₃R/Ca²⁺ pathway. E₂/ER subtypes immediately induced endothelial-derived hyperpolarization (EDH)-mediated vasorelaxation via PLC/IP₃R/Ca²⁺ pathway, which was more impaired in septic male mice. E₂/ER subtypes could rescue the impaired acetylcholine (ACh)-induced EDH-mediated vasorelaxation in septic male mice.

Conclusions

E₂ through ER subtypes mediates anti-inflammation and vasorelaxation via genomic and nongenomic actions in sepsis. Mechanistically, activation of endothelial ER subtypes reduces proinflammatory cytokines and induces EDH-mediated vasorelaxation via PLC/IP₃R/Ca²⁺ pathway, leading to amelioration of sepsis-induced organ injury and survival rate.