Sex as a prognostic factor for mortality in critically ill adults with sepsis: a systematic review and meta-analysis

Clinical biomarker profiles reveals gender differences and mortality factors in sepsis

Background

Sepsis is a major contributor to global morbidity and mortality, affecting millions each year. Notwithstanding the decline in sepsis incidence and mortality over decades, gender disparities in sepsis outcomes persist, with research suggesting higher mortality rates in males.

Methods

This retrospective study aims to delineate gender-specific clinical biomarker profiles impacting sepsis progression and mortality by examining sepsis cases and related clinical data from the past three years. Propensity score matching was used to select age-matched healthy controls for comparison.

Results

Among 265 sepsis patients, a significantly higher proportion were male (60.8%, P<0.001). While mortality did not significantly differ by gender, deceased patients were significantly older (mean 69 vs 43 years, P=0.003), more likely to have hypertension (54% vs 25%, P=0.019), and had higher SOFA scores (mean ~10 vs 4, P<0.01) compared to survivors. Principal Component Analysis (PCA) showed clear separation between sepsis patients and healthy controls. 48 serum biomarkers were significantly altered in sepsis, with Triiodothyronine, Apolipoprotein A, and Serum cystatin C having the highest diagnostic value by ROC analysis. Gender-stratified comparisons identified male-specific (e.g. AFP, HDLC) and female-specific (e.g. Rheumatoid factor, Interleukin-6) diagnostic biomarkers. Deceased patients significantly differed from survivors, with 22 differentially expressed markers; Antithrombin, Prealbumin, HDL cholesterol, Urea nitrogen and Hydroxybutyrate had the highest diagnostic efficiency for mortality.

Conclusion

These findings enhance our understanding of gender disparities in sepsis and may guide future therapeutic strategies. Further research is warranted to validate these biomarker profiles and investigate the molecular mechanisms underlying these gender differences in sepsis outcomes.

Sex or gender differences in treatment outcomes of sepsis and septic shock

Gender disparities in intensive care unit (ICU) treatment approaches and outcomes are evident. However, clinicians often pay little attention to the importance of biological sex and sociocultural gender in their treatment courses. Previous studies have reported that differences between sexes or genders can significantly affect the manifestation of diseases, diagnosis, clinicians' treatment decisions, scope of treatment, and treatment outcomes in the intensive care field. In addition, numerous reports have suggested that immunomodulatory effects of sex hormones and differences in gene expression from X chromosomes between genders might play a significant role in treatment outcomes of various diseases. However, results from clinical studies are conflicting. Recently, the need for customized treatment based on physical, physiological, and genetic differences between females and males and sociocultural characteristics of society have been increasingly emphasized. However, interest in and research into this field are remarkably lacking in Asian countries, including South Korea. Through this review, we hope to enhance our awareness of the importance of sex and gender in intensive care treatment and research by briefly summarizing several principal issues, mainly focusing on sex and sex hormone-based outcomes in patients admitted to the ICU with sepsis and septic shock.

Risk Factors and Scoring Systems to Predict the Mortality Risk of Afebrile Adult Patients with Monomicrobial Gram-Negative Bacteremia: A 10-Year Observational Study in the Emergency Department

BACKGROUND

The mortality rate of afebrile bacteremia has been reported to be as high as 45%. This investigation focused on the risk factors and predictive performance of scoring systems for the clinical outcomes of afebrile patients with monomicrobial gram-negative bacteria (GNB) in the emergency department (ED).

METHODS

We conducted a retrospective analysis of afebrile adult ED patients with monomicrobial GNB bacteremia from January 2012 to December 2021. We dissected the demographics, clinical pictures, and laboratory investigations. We applied five scoring systems and three revised systems to predict the clinical outcomes.

RESULTS

There were 600 patients included (358 males and 242 females), with a mean age of 69.6 ± 15.4 years. The overall mortality rate was 50.17%, reaching 68.52% (74/108) in cirrhotic patients. Escherichia coli was the leading pathogen (42.83%). The non-survivors had higher scores of the original MEDS (p < 0.001), NEWS (p < 0.001), MEWS (p < 0.001), qSOFA (p < 0.001), and REMS (p = 0.030). In univariate logistic regression analyses, several risk factors had a higher odds ratio (OR) for mortality, including liver cirrhosis (OR 2.541, p < 0.001), malignancy (OR 2.259, p < 0.001), septic shock (OR 2.077, p = 0.002), and male gender (OR 0.535, p < 0.001). The MEDS demonstrated that the best predictive power with the maximum area under the curve (AUC) was measured at 0.773 at the cut-off point of 11. The AUCs of the original NEWS, MEWS, qSOFA, and REMS were 0.663, 0.584, 0.572, and 0.553, respectively. We revised the original MEDS, NEWS, and qSOFA by adding red cell distribution width, albumin, and lactate scores and found a better predictive power of the AUC of 0.797, 0.719, and 0.694 on the revised MEDS ≥11, revised qSOFA ≥ 3, and revised NEWS ≥ 6, respectively.

CONCLUSIONS

The original MEDS, revised MEDS, revised qSOFA, and revised NEWS were valuable tools for predicting the mortality risk in afebrile patients with monomicrobial GNB bacteremia. We suggested that clinicians should explore patients with the risk factors mentioned above for possible severe infection, even in the absence of fever and initiate hemodynamic support and early adequate antibiotic therapy in patients with higher scores of the original MEDS (≥11), revised MEDS (≥11), revised NEWS (≥6), and revised qSOFA (≥3).

Obesity and septic patient outcomes: Shaping the puzzle through age and sex perspectives

BACKGROUND & AIMS

While obesity has been reported as a protective factor in septic patients, little is known about the potential modifying effects of age and sex. The objective of this study is to investigate age and sex-specific associations between obesity and the prognosis of septic patients.

METHODS

A retrospective analysis was conducted on a cohort of 15,464 septic patients, categorized by body mass index (BMI) into four groups: underweight (<18.5 kg/m2, n = 483), normal (18.5-24.9 kg/m2, n = 4344), overweight (25-29.9 kg/m2, n = 4949) and obese (≥30 kg/m2, n = 5688). Multivariable logistic regression and inverse probability weighting were employed to robustly confirm the protective effect of a higher BMI on 28-day mortality, with normal weight serving as the reference category. Subgroup analyses based on age (young: 18-39, middle-aged: 40-64 and elderly: ≥65) and sex were performed.

RESULTS

The findings demonstrate that high BMI independently confers a protective effect against 28-day mortality in septic patients. However, the relationship between BMI and 28-day mortality exhibits a non-linear trend, with a BMI of 34.5 kg/m2 displaying the lowest odds ratio. Notably, the survival benefits associated with a high BMI were not observed in the young group. Moreover, being underweight emerges as an independent risk factor for middle-aged and elderly female patients, while in males it is only a risk factor in the elderly group. Interestingly, being overweight and obese were identified as independent protective factors in middle-aged and elderly male patients, but not in females.

CONCLUSIONS

The effect of BMI on mortality in septic patients varies according to age and sex. Elderly individuals with sepsis may derive more prognostic benefits from obesity.

Low circulatory levels of total cholesterol, HDL-C and LDL-C are associated with death of patients with sepsis and critical illness: systematic review, meta-analysis, and perspective of observational studies

BACKGROUND

Mechanistic studies have established a biological role of sterol metabolism in infection and immunity with clinical data linking deranged cholesterol metabolism during sepsis with poorer outcomes. In this systematic review we assess the relationship between biomarkers of cholesterol homeostasis and mortality in critical illness.

METHODS

We identified articles by searching a total of seven electronic databases from inception to October 2023. Prospective observational cohort studies included those subjects who had systemic cholesterol (Total Cholesterol (TC), HDL-C or LDL-C) levels assessed on the first day of ICU admission and short-term mortality recorded. Meta-analysis and meta-regression were used to evaluate overall mean differences in serum cholesterol levels between survivors and non-survivors. Study quality was assessed using the Newcastle-Ottawa Scale.

FINDINGS

From 6469 studies identified by searches, 24 studies with 2542 participants were included in meta-analysis. Non-survivors had distinctly lower HDL-C at ICU admission -7.06 mg/dL (95% CI -9.21 to -4.91, p < 0.0001) in comparison with survivors. Corresponding differences were also seen less robustly for TC -21.86 mg/dL (95% CI -31.23 to -12.49, p < 0.0001) and LDL-C -8.79 mg/dL (95% CI, -13.74 to -3.83, p = 0.0005).

INTERPRETATION

Systemic cholesterol levels (TC, HDL-C and LDL-C) on admission to critical care are inversely related to mortality. This finding is consistent with the notion that inflammatory and metabolic setpoints are coupled, such that the maladaptive-setpoint changes of cholesterol in critical illness are related to underlying inflammatory processes. We highlight the potential of HDL-biomarkers as early predictors of severity of illness and emphasise that future research should consider the metabolic and functional heterogeneity of HDLs.

FUNDING

EU-ERDF-Welsh Government Ser Cymru programme, BBSRC, and EU-FP7 ClouDx-i project (PG).

Sepsis heterogeneity

BACKGROUND

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, with extremely high mortality. Notably, sepsis is a heterogeneous syndrome characterized by a vast, multidimensional array of clinical and biologic features, which has hindered advances in the therapeutic field beyond the current standards.

DATA SOURCES

We used PubMed to search the subject-related medical literature by searching for the following single and/or combination keywords: sepsis, heterogeneity, personalized treatment, host response, infection, epidemiology, mortality, incidence, age, children, sex, comorbidities, gene susceptibility, infection sites, bacteria, fungi, virus, host response, organ dysfunction and management.

RESULTS

We found that host factors (age, biological sex, comorbidities, and genetics), infection etiology, host response dysregulation and multiple organ dysfunctions can all result in different disease manifestations, progression, and response to treatment, which make it difficult to effectively treat and manage sepsis patients.

CONCLUSIONS

Herein, we have summarized contributing factors to sepsis heterogeneity, including host factors, infection etiology, host response dysregulation, and multiple organ dysfunctions, from the key elements of pathogenesis of sepsis. An in-depth understanding of the factors that contribute to the heterogeneity of sepsis will help clinicians understand the complexity of sepsis and enable researchers to conduct more personalized clinical studies for homogenous patients.

Association of Sex and Age with Mortality and Health-Related Quality of Life in Children with Septic Shock: A Secondary Analysis of the Life After Pediatric Sepsis Evaluation

Introduction: Sepsis is more common in males than females, but whether outcomes differ by sex in various pediatric age groups is unclear. The Life After Pediatric Sepsis Evaluation (LAPSE) was a multicenter prospective cohort study that evaluated health-related quality of life (HRQL) in children after community-acquired septic shock. In this secondary analysis, we evaluated whether male children are at increased risk of mortality or long-term decline in HRQL than female children by age group. Methods: Children (1 month-18 years) with community-acquired septic shock were recruited from 12 pediatric intensive care units in the U.S. Data included sex, age group (<1 year, 1-<13 years, 13-18 years), acute illness severity (acute organ dysfunction and inflammation), and longitudinal assessments of HRQL and mortality. Persistent decline in HRQL was defined as a 10% decrease in HRQL comparing baseline to 3 months following admission. Male and female children were stratified by age group and compared to evaluate the difference in the composite outcome of death or persistent decline in HRQL using the Cochran-Mantel-Haenszel test. Results: Of 389 children, 54.2% (n = 211) were male. Overall, 10% (21/211) of males and 12% (22/178) of females died by 3 months (p = 0.454). Among children with follow-up data, 41% (57/138) of males and 44% (48/108) of females died or had persistent decline in HRQL at 3 months (p = 0.636), with no observed difference by sex when stratified by age group. There was no significant difference in acute illness severity between males and females overall or stratified by age group. Conclusions: In this secondary analysis of the LAPSE cohort, HRQL, and mortality were not different between male and female children when stratified by age group. There were no significant differences by sex across multiple measures of illness severity or treatment intensity.

Influence of gender on age-associated in-hospital mortality in patients with sepsis and septic shock: a prospective nationwide multicenter cohort study

BACKGROUND

Numerous epidemiological studies investigating gender-dependent clinical outcomes in sepsis have shown conflicting evidence. This study aimed to investigate the effect of gender on in-hospital mortality due to sepsis according to age group.

METHODS

This study used data from the Korean Sepsis Alliance, an ongoing nationwide prospective multicenter cohort from 19 participating hospitals in South Korea. All adult patients diagnosed with sepsis in the emergency departments of the participating hospitals between September 2019 and December 2021 were included in the analysis. Clinical characteristics and outcomes were compared between male and female. Eligible patients were stratified by age into 19-50 years, 50-80 years, and ≥ 80 years old individuals.

RESULTS

During the study period, 6442 patients were included in the analysis, and 3650 (56.7%) were male. The adjusted odds ratio (OR) [95% confidence interval (CI)] for in-hospital mortality for male compared with female was 1.15 (95% CI = 1.02-1.29). Interestingly, in the age 19-50 group, the risk of in-hospital mortality for males was significantly lower than that of females [0.57 (95% CI = 0.35-0.93)]. For female, the risk of death remained relatively stable until around age 80 (P for linearity = 0.77), while in males, there was a linear increase in the risk of in-hospital death until around age 80 (P for linearity < 0.01). Respiratory infection (53.8% vs. 37.4%, p < 0.01) was more common in male, whereas urinary tract infection (14.7% vs. 29.8%, p < 0.01) was more common in female. For respiratory infection, male had significantly lower in-hospital mortality than female in the age 19-50 groups (adjusted OR = 0.29, 95% CI = 0.12-0.69).

CONCLUSIONS

Gender may influence age-associated sepsis outcomes. Further studies are needed to replicate our findings and fully understand the interaction of gender and age on the outcomes of patients with sepsis.

Interactions between Gender and Sepsis—Implications for the Future

Sex and gender dimorphisms are found in a large variety of diseases, including sepsis and septic shock which are more prevalent in men than in women. Animal models show that the host response to pathogens differs in females and males. This difference is partially explained by sex polarization of the intracellular pathways responding to pathogen–cell receptor interactions. Sex hormones seem to be responsible for this polarization, although other factors, such as chromosomal effects, have yet to be investigated. In brief, females are less susceptible to sepsis and seem to recover more effectively than males. Clinical observations produce more nuanced findings, but men consistently have a higher incidence of sepsis, and some reports also claim higher mortality rates. However, variables other than hormonal differences complicate the interaction between sex and sepsis, including comorbidities as well as social and cultural differences between men and women. Conflicting data have also been reported regarding sepsis-attributable mortality rates among pregnant women, compared with non-pregnant females. We believe that unraveling sex differences in the host response to sepsis and its treatment could be the first step in personalized, phenotype-based management of patients with sepsis and septic shock.

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

OBJECTIVE

To determine the effect of sex on sepsis-related ICU admission and survival for up to 3-years.

METHODS

Retrospective cohort study of adults admitted to Australian ICUs between 2018 and 2020. Men and women with a primary diagnosis of sepsis were included. The primary outcome of time to death for up to 3-years was examined using Kaplan Meier plots. Secondary outcomes included the duration of ICU and hospital stay.

RESULTS

Of 523,576 admissions, there were 63,039 (12·0%) sepsis-related ICU admissions. Of these, there were 50,956 patients (43·4% women) with 3-year survival data. Men were older (mean age 66·5 vs 63·6 years), more commonly received mechanical ventilation (27·4% vs 24·7%) and renal replacement therapy (8·2% vs 6·8%) and had worse survival (Hazard Ratio [HR] 1·11; 95% Confidence Interval [CI] 1·07 to 1·14, P<0·001) compared to women. The duration of hospital and ICU stay was longer for men, compared to women (median hospital stay, 9.8 vs 9.4 days; p<0.001 and ICU stay, 2.7 vs 2.6 days; p<0.001).

CONCLUSION

Men are more likely to be admitted to ICU with sepsis and have worse survival for up to 3-years. Understanding causal mechanisms of sex differences may facilitate the development of targeted sepsis strategies.

Sex differences in cardiovascular response to sepsis

Recently, there has been increased recognition of the importance of sex as a biological factor affecting disease and health. Many preclinical studies have suggested that males may experience a less favorable outcome in response to sepsis than females. The underlying mechanisms for these differences are still largely unknown but are thought to be related to the beneficial effects of estrogen. Furthermore, the immunosuppressive role of testosterone is also thought to contribute to the sex-dependent differences that are present in clinical sepsis. There are still significant knowledge gaps in this field. This mini-review will provide a brief overview of sex-dependent variables in relation to sepsis and the cardiovascular system. Preclinical animal models for sepsis research will also be discussed. The intent of this mini-review is to inspire interest for future considerations of sex-related variables in sepsis that should be addressed to increase our understanding of the underlying mechanisms in sepsis-induced cardiovascular dysfunction for the identification of therapeutic targets and improved sepsis management and treatment.

Sex differences in clinical presentation and mortality in emergency department patients with sepsis

BACKGROUND

There is growing awareness that sex differences are associated with different patient outcomes in a variety of diseases. Studies investigating the effect of patient sex on sepsis-related mortality remain inconclusive and mainly focus on patients with severe sepsis and septic shock in the intensive care unit. We therefore investigated the association between patient sex and both clinical presentation and 30-day mortality in patients with the whole spectrum of sepsis severity presenting to the emergency department (ED) who were admitted to the hospital.

MATERIALS AND METHODS

In our multi-centre cohort study, we retrospectively investigated adult medical patients with sepsis in the ED. Multivariable analysis was used to evaluate the association between patient sex and all-cause 30-day mortality.

RESULTS

Of 2065 patients included, 47.6% were female. Female patients had significantly less comorbidities, lower Sequential Organ Failure Assessment score and abbreviated Mortality Emergency Department Sepsis score, and presented less frequently with thrombocytopenia and fever, compared to males. For both sexes, respiratory tract infections were predominant while female patients more often had urinary tract infections. Females showed lower 30-day mortality (10.1% vs. 13.6%; p = .016), and in-hospital mortality (8.0% vs. 11.1%; p = .02) compared to males. However, a multivariable logistic regression model showed that patient sex was not an independent predictor of 30-day mortality (OR 0.90; 95% CI 0.67-1.22; p = .51).

CONCLUSIONS

Females with sepsis presenting to the ED had fewer comorbidities, lower disease severity, less often thrombocytopenia and fever and were more likely to have a urinary tract infection. Females had a lower in-hospital and 30-day mortality compared to males, but sex was not an independent predictor of 30-day mortality. The lower mortality in female patients may be explained by differences in comorbidity and clinical presentation compared to male patients.KEY MESSAGESOnly limited data exist on sex differences in sepsis patients presenting to the emergency department with the whole spectrum of sepsis severity.Female sepsis patients had a lower incidence of comorbidities, less disease severity and a different source of infection, which explains the lower 30-day mortality we found in female patients compared to male patients.We found that sex was not an independent predictor of 30-day mortality; however, the study was probably underpowered to evaluate this outcome definitively.

Explaining sex differences in risk of bloodstream infections using mediation analysis in the population-based HUNT study in Norway

Previous studies indicate sex differences in incidence and severity of bloodstream infections (BSI). We examined the effect of sex on risk of BSI, BSI mortality, and BSI caused by the most common infecting bacteria. Using causal mediation analyses, we assessed if this effect is mediated by health behaviours (smoking, alcohol consumption), education, cardiovascular risk factors (systolic blood pressure, non-HDL cholesterol, body mass index) and selected comorbidities. This prospective study included 64,040 participants (46.8% men) in the population-based HUNT2 Survey (1995-1997) linked with hospital records in incident BSI. During median follow-up of 15.2 years, 1840 (2.9%) participants (51.3% men) experienced a BSI and 396 (0.6%) died (56.6% men). Men had 41% higher risk of first-time BSI (95% confidence interval (CI), 28-54%) than women. Together, health behaviours, education, cardiovascular risk factors and comorbidities mediated 34% of the excess risk of BSI observed in men. The HR of BSI mortality was 1.87 (95% CI 1.53-2.28), for BSI due to S. aureus 2.09 (1.28-2.54), S. pneumoniae 1.36 (1.05-1.76), E. coli 0.97 (0.84-1.13) in men vs women. This study shows that men have higher risk of BSI and BSI mortality than women. One-third of this effect was mediated by potential modifiable risk factors for incident BSI.