Sex-dependent disparities in critical illness: methodological implications for critical care research

Gender- and age-based differences in outcomes of mechanically ventilated ICU patients: a Chinese multicentre retrospective study

BACKGROUND

Previous studies have suggested that the gender and/or age of a patient may influence the clinical outcomes of critically ill patients. Our aim was to determine whether there are gender- and age-based differences in clinical outcomes for mechanically ventilated patients in intensive care units (ICUs).

METHODS

We performed a multicentre retrospective study involving adult patients who were admitted to the ICU and received at least 24 h of mechanical ventilation (MV). The patients were divided into two groups based on gender and, subsequently, further grouped based on gender and age < or ≥ 65 years. The primary outcome measure was hospital mortality.

RESULTS

A total of 853 mechanically ventilated patients were evaluated. Of these patients, 63.2% were men and 61.5% were ≥ 65 years of age. The hospital mortality rate for men was significantly higher than that for women in the overall study population (P = 0.042), and this difference was most pronounced among elderly patients (age ≥ 65 years; P = 0.006). The durations of MV, ICU lengths of stay (LOS), and hospital LOS were significantly longer for men than for women among younger patients (P ≤ 0.013) but not among elderly patients. Multivariate logistic regression analysis revealed that male gender was independently associated with hospital mortality among elderly patients but not among younger patients.

CONCLUSIONS

There were important gender- and age-based differences in the outcomes among mechanically ventilated ICU patients. The combination of male gender and advanced age is strongly associated with hospital mortality.

Systematic review of gender- dependent outcomes in sepsis

BACKGROUND

Men and women appear to exhibit different susceptibilities to sepsis and possibly divergent outcomes. However, the effect of sex and gender in critical illness outcomes is still controversial and the underlying mechanisms appear to be complex.

OBJECTIVES

We aimed to systematically review and synthesize evidence on the influence of sex on outcomes in critically ill adult patients with sepsis, as reported in published studies specifically including investigation of the effect of sex among their aims. Primary outcome measures include in-hospital mortality, intensive care unit (ICU) mortality and length of stay (LOS) in the ICU.

SEARCH STRATEGY

The review was based on focused literature searches (CINAHL, PUBMED, EMBASE and COCHRANE). Methodological quality was assessed through the STROBE checklist and the Cochrane Tool for Bias in Cohort Studies. Meta-analysis was performed using STATA. Published observational studies addressing outcomes of sepsis among their primary aims and having included gender comparisons among primary outcomes in critically ill adult patients were included.

RESULTS

A total of eight eligible studies were included. With the exception of mortality, it was not possible to perform meta-analysis for other outcomes. Included studies reported data on 25,619 patients with sepsis (14 309 male/11 310 female). There is a paucity of well-designed studies addressing the effect of sex on mortality among patients with sepsis, and absence of studies addressing the effects of sex on multiple organ dysfunction of non-infectious origin. There was significant heterogeneity among study estimates (p = 0·001; I² =78·1%).

CONCLUSIONS

Although results of data syntheses appear to point towards a small disadvantage for survival among women, our results suggest that data on the impact of sex on sepsis outcomes remain equivocal. Implications for future research include approaches to adjustment for confounders and prospective designs.

RELEVANCE TO CLINICAL PRACTICE

Clarifying sex-related differences in sepsis, if any, is crucial for informing evidence-based care.

Association between lymphocyte expression of the apoptotic receptor Fas and pain in critically ill patients

Objective

Lymphocyte apoptosis in critical illness is associated with immunosuppression. We explored for the first time the associations between pain ratings and expression of the apoptotic receptor Fas on B and T cells in critically ill patients and the potential mediating effects of adrenocorticotropic hormone (ACTH), cortisol, and substance P (SP).

Design

This is an exploratory correlational study with repeated measurements (14 days followup) and cross-sectional comparisons.

Setting

This study was conducted in a state hospital in the metropolitan area of Athens, Greece.

Participants

The participants were 36 consecutive critically ill patients and 36 matched controls.

Outcome measures

Pain measured by the self-reported numeric rating scale [NRS], the behavioral pain scale, and the pain assessment scale was the primary outcome measure. Flow cytometry (Fas), electrochemiluminescence (ACTH and cortisol) and enzyme-linked immunosorbent assay (SP) were used. Mixed linear models for repeated measurements and bivariable associations at discrete time points were employed.

Results

Significant pain at rest was noted. Pain ratings associated with Fas expression on cytotoxic T cells (P=0.041) and B cells (P=0.005), even after adjustment for a number of clinical treatment factors (P=0.006 and P=0.052, respectively). On the day that more patients were able to communicate, Fas on B cells (r=0.897, P=0.029) and cytotoxic T cells (r=0.832; P=0.037) associated with NRS ratings. Associations between pain ratings and ACTH serum levels were noted (P<0.05). When stress neuropeptide levels were added to the model, the statistical significance of the associations between pain ratings and Fas expression was attenuated (P=0.052–0.063), suggesting that stress neuropeptides may partially mediate the association.

Conclusion

Preliminary evidence for the association between pain and lymphocyte apoptotic susceptibility is provided. The role of pain management in maintaining immunocompetence in critical illness is worth exploring.

The Impact of Pain Assessment on Critically Ill Patients' Outcomes: A Systematic Review

In critically ill patients, pain is a major problem. Efficient pain management depends on a systematic, comprehensive assessment of pain. We aimed to review and synthesize current evidence on the impact of a systematic approach to pain assessment on critically ill patients' outcomes. A systematic review of published studies (CINAHL, PUBMED, SCOPUS, EMBASE, and COCHRANE databases) with predetermined eligibility criteria was undertaken. Methodological quality was assessed by the EPHPP quality assessment tool. A total of 10 eligible studies were identified. Due to big heterogeneity, quantitative synthesis was not feasible. Most studies indicated the frequency, duration of pain assessment, and types of pain assessment tools. Methodological quality assessment yielded “strong” ratings for 5/10 and “weak” ratings for 3/10 studies. Implementation of systematic approaches to pain assessment appears to associate with more frequent documented reports of pain and more efficient decisions for pain management. There was evidence of favorable effects on pain intensity, duration of mechanical ventilation, length of ICU stay, mortality, adverse events, and complications. This systematic review demonstrates a link between systematic pain assessment and outcome in critical illness. However, the current level of evidence is insufficient to draw firm conclusions. More high quality randomized clinical studies are needed.