Gender modifies the influence of age on outcome after successfully resuscitated cardiac arrest: a retrospective cohort study

Comparison of smokers' mortality with non-smokers following out-of-hospital cardiac arrests: a systematic review and meta-analysis

OBJECTIVE

Although some studies have linked smoking to mortality after out-of-hospital cardiac arrests (OHCAs), data regarding smoking and mortality after OHCAs have not yet been discussed in a meta-analysis. Thus, this study conducted this systematic review to clarify the association.

METHODS

The study searched Medline-PubMed, Web of Science, Embase and Cochrane libraries between January 1972 and July 2022 for studies that evaluated the association between smoking and mortality after OHCAs. Studies that reportedly showed relative risk estimates with 95% confidence intervals (CIs) were included.

RESULTS

Incorporating a collective of five studies comprising 2477 participants, the analysis revealed a lower mortality risk among smokers in the aftermath of OHCAs compared with non-smokers (odds ratio: 0.77; 95% CI 0.61-0.96; P < 0.05). Egger's test showed no publication bias in the relationship between smoking and mortality after OHCAs.

CONCLUSIONS

After experiencing OHCAs, smokers had lower mortality than non-smokers. However, due to the lack of data, this 'smoker's paradox' still needs other covariate effects and further studies to be considered valid.

Sex and out-of-hospital cardiac arrest survival: a systematic review

BACKGROUND

The literature is unresolved on whether female receive advanced cardiac life support less than do male and on whether female have a survival advantage over male after cardiopulmonary resuscitation.

METHODS

We systematically searched PubMed, Embase and Web of Science databases (from inception to 23-April-2022) for papers reporting outcomes in adult male and female after out-of-hospital cardiac arrest. The main study outcome was the rate of adjusted survival to hospital discharge or 30 days. Secondary outcomes included unadjusted survival to hospital discharge and favourable neurological outcome.

RESULTS

A total of 28 studies were included, involving 1,931,123 patients. Female were older than male, their cardiac arrests were less likely to be witnessed and less likely to present with a shockable rhythm. Unadjusted analysis showed that females had a lower likelihood of survival than males (OR 0.68 [0.62-0.74], I2 = 97%). After adjustment, no significant difference was identified between male and female in survival at hospital discharge/30 days (OR 1.01 [0.93-1.11], I2 = 87%). Data showed that male had a significantly higher likelihood of favorable neurological outcome in unadjusted analysis but this trend disappeared after adjustment. Both the primary outcome (adjusted for several variables) and the secondary outcomes were associated with substantial heterogeneity. The variables examined using meta-regression, subgroup and sensitivity analyses (i.e., study type, location, years, population, quality of adjustment, risk of bias) did not reduce heterogeneity.

CONCLUSIONS

The adjusted rate of survival to hospital discharge/30 days was similar for male and female despite an initial seeming survival advantage for male. The validity of this finding is limited by substantial heterogeneity despite in-depth investigation of its causes, which raises concerns regarding latent inequalities in some reports nonetheless. Further study on this topic may require inclusion of factors not reported in the Utstein template and in-depth analysis of decision-making processes.

Association between sex and survival after non-traumatic out of hospital cardiac arrest: A systematic review and meta-analysis

BACKGROUND

Existing studies have shown conflicting results regarding the relationship of sex with survival after out of hospital cardiac arrest (OHCA). This systematic review evaluates the association of female sex with survival to discharge and survival to 30 days after non-traumatic OHCA.

METHODS

We searched Medline, Embase, CINAHL, Web of Science, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews from inception through June 2021 for studies evaluating female sex as a predictor of survival in adult patients with non-traumatic cardiac arrest. Random-effects inverse variance meta-analyses were performed to calculate pooled odds ratios (ORs) with 95% confidence intervals (CI). The GRADE approach was used to assess evidence quality.

RESULTS

Thirty studies including 1,068,788 patients had female proportion of 41%. There was no association for female sex with survival to discharge (OR 1.03, 95% CI 0.95-1.12; I²=89%). Subgroup analysis of low risk of bias studies demonstrated increased survival to discharge for female sex (OR 1.20, 95% CI 1.18-1.23; I²=0%) and with high certainty, the absolute increase in survival was 2.2% (95% CI 0.1%-3.6%). Female sex was not associated with survival to 30 days post-OHCA (OR 1.02, 95% CI 0.92-1.14; I²=79%).

CONCLUSIONS

In adult patients experiencing OHCA, with high certainty in the evidence from studies with low risk of bias, female sex had a small absolute difference for the outcome survival to discharge and no difference in survival at 30 days. Future models that aim to stratify risk of survival post-OHCA should focus on sex-specific factors as opposed to sex as an isolated prognostic factor.

National Early Warning Score in Predicting Severe Adverse Outcomes of Emergency Medicine Patients: A Retrospective Cohort Study

Background

For emergency triage, it is very important to identify patient severity according to their vital signs and chief complaint. Several studies have examined the predictive value of the National Early Warning Score (NEWS) for specific emergency patients and have shown it to be effective. However, few have studied the utility of NEWS in emergency triage for general emergency medicine patients. The aim of this research was to investigate the performance of NEWS in emergency triage with regard to predicting adverse outcomes.

Methods

This was a retrospective cohort study carried out at a tertiary care center hospital in Jinhua, China. A total of 62,403 patients attending the emergency department (ED) from January to December 2018 were included. The NEWS, Modified Early Warning Score (MEWS), and quick Sepsis Related Organ Failure Assessment (qSOFA) score were obtained from emergency triage. Multivariate logistic regression analysis was performed to evaluate the associations between the NEWS, MEWS, and qSOFA, as well as those between other parameters with ED mortality. The predictive performances for emergency observation, death, and intensive care unit (ICU) admission of NEWS, MEWS and qSOFA were compared to the area under the receiver operating characteristic curve (AUROC).

Results

Of the total participants, 6502 were placed under emergency observation, 106 died in the ED, 638 were admitted to the ICU, and 324 died in-hospital. The NEWS, qSOFA, age, and gender were significantly associated with ED mortality. NEWS was significantly better at discriminating all outcomes, and the area under the curve and 95% confidence intervals for ED mortality, observation in ED, composite of ED mortality and ICU admission, and in-hospital mortality were 0.862 (0.859-0.865), 0.691 (0.687-0.695), 0.859 (0.856-0.861), and 0.805 (0.802-0.808), respectively.

Conclusion

NEWS shows good performance in discriminating critical emergency patients in ED triage for emergency medicine patients.

Gender differences and survival after an out-of-hospital cardiac arrest: a systematic review and meta-analysis

Patients who experience out-of-hospital cardiac arrest (OHCA) have unacceptably high mortality rates. It remains unclear whether gender has an association with survival in this regard. Hence, we aimed to investigate the association between gender and survival by conducting a systematic review and meta-analysis. The databases of PubMed, Embase, and Cochrane Database of Systematic Reviews were searched from inception to 17 March, 2020. Studies assessing the association between gender and survival to discharge or 30-day survival after OHCA were included. Two reviewers independently assessed the eligibility of the identified studies. The random-effects model was used to pool data, and the outcome was reported as odds ratios (ORs) and 95% confidence intervals, as the relative measure of association. Twenty-three eligible studies enrolling 897,805 patients were included in this systematic review. Overall, women were older and less likely to experience arrest in public places. When arrest occurred, women had less initial shockable rhythm, were less likely to be witnessed by bystanders, and were less likely provided with CPR compared with men. After admission, women underwent less coronary angiography, percutaneous coronary angiography, and targeted temperature management therapy. Eleven studies with ORs were pooled, showing a significant survival benefit in women (OR = 1.08, p < 0.05, I² = 52.3%). In the subgroup analysis, both premenopausal women (< 50 years) (OR = 1.42, p < 0.001, I² = 0%) and postmenopausal women (≥ 50 years) (OR = 1.07, p < 0.05, I² = 16.4%) had higher odds of survival compared with age-matched men. Despite the unfavorable factors, the pooled results showed a significant survival benefit in women after OHCA, especially in premenopausal women.

Impact of Racial and Gender Variations in Patients With Out-of-hospital Cardiac Arrest: A Nation-Wide Study

The overall incidence of Out-of-hospital Cardiac Arrest (OHCA) is decreasing worldwide due to emergency responses, but there are gender and racial differences in the incidence of OHCA, which remain under investigation. Our aim was to identify the incidence, gender, and racial disparities in patients admitted with OHCA. The National Inpatient Sample Database is one of the largest all-payer inpatient database. It was queried to identify patients 18 years or older who were hospitalized with the principal diagnosis of OHCA. There was a total of 85,988 patients who were discharged with a diagnosis classified as OHCA using the ICD-9 code for a period of 2 years. The mean age of the patients who had presented to the hospital with OHCA was 64.3 (±18.5 years). Overall, a greater number of males suffered from OHCA were compared with female population of (48,635 vs 37,366; P < 0.0001). The incidence of OHCA was higher among Caucasians as compared with African Americans (54,812, 63.8% vs 13,787, 16%; P < 0.0001). In-hospital deaths after OHCA were 43,024 (50%). But African Americans had higher mortality than Caucasians after hospitalization for OHCA (adjusted odds ratio, 1.23; 95% confidence interval, 1.18-1.26; P < 0.01). We observed significant differences in gender and racial factors in the patients who were admitted to the hospital with a diagnosis of OHCA based on an analysis of the national inpatient database.

Outcome analysis of traumatic out-of-hospital cardiac arrest patients according to the mechanism of injury: A nationwide observation study

The variation in the outcome of traumatic out-of-hospital cardiac arrest (TOHCA) patients according to the mechanism of injury has been relatively unexplored. Therefore, this study aimed to determine whether the mechanism of injury is associated with survival to hospital discharge and good neurological outcome at hospital discharge in TOHCA.The study population comprised cases of TOHCA drawn from the national Out-of-hospital cardiac arrest registry (2012-2016). Traumatic causes were categorized into 6 groups: traffic accident, fall, collision, stab injury, and gunshot injury. Data were retrospectively extracted from emergency medical service and Korean Centers for Disease Control and Prevention records. Multivariate logistic regression analysis was used to identify factors associated with survival to discharge and good neurological outcome.The final analysis included a total of 8546 eligible TOHCA patients (traffic accident 5300, fall 2419, collision 572, stab injury 247, and gunshot injury 8). The overall survival rate was 18.4% (traffic accident 18.0%, fall 16.4%, collision 32.0%, stab injury 14.2%, and gunshot injury 12.5%). Good neurological outcome was achieved in 0.8% of all patients (traffic accident 0.8%, fall 0.8%, collision 1.2%, stab injury 0.8%, and gunshot injury 0.0%). In the multivariate analysis, injury mechanisms showed no significant difference in neurological outcomes, and only collision had a significant odds ratio for survival to discharge (odds ratio: 2.440; 95% confidence interval: 1.795-3.317) compared to the traffic accident group.In this study, the mechanism of injury was not associated with neurological outcome in TOHCA patients. Collision might be the only mechanism of injury to result in better survival to discharge than traffic accident.

Sex differences in survival after out-of-hospital cardiac arrest: a meta-analysis

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) is a leading cause of sudden cardiac death worldwide. Researchers have found significant pathophysiological differences between females and males and clinically significant sex differences related to medical services. However, conflicting results exist and there is no uniform agreement regarding sex differences in survival and prognosis after OHCA. Therefore, we investigated the relationship between the prognosis of OHCA and sex factors.

METHODS

We comprehensively searched the PubMed, Embase, and Cochrane databases and obtained a total of 1042 articles, from which 33 studies were selected for inclusion. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using a random-effects model.

RESULTS

The meta-analysis included 1,268,664 patients. Compared with males, females were older (69.7 years vs. 65.4 years, p < 0.05) and more frequently suffered OHCA without witnesses (58.39% vs 62.70%, p < 0.05). Females were less likely to receive in-hospital interventions than males. There was no significant difference between females and males in the survival from OHCA to hospital admission (OR 0.99, 95% CI 0.89-1.1). However, females had lower chances for survival from hospital admission to discharge (OR 0.59, 95% CI 0.48-0.73), overall survival to hospital discharge (OR 0.73, 95% CI 0.62-0.86), and favorable neurological outcomes (OR 0.62, 95% CI 0.47-0.83) compared with males.

CONCLUSIONS

Our results indicate that the overall discharge survival rate of females is lower than that of males, and females face a poor prognosis of the nervous system. This is likely related to the pathophysiological characteristics of females, more conservative treatment measures compared with males, and different post-resuscitation care. However, these findings should be interpreted with caution due to the presence of several confounding factors.

Prognostic factors related with outcomes in traumatic out-of-hospital cardiac arrest patients without prehospital return of spontaneous circulation: a nationwide observational study

OBJECTIVE

To evaluate the prognostic factors associated with the sustained return of spontaneous circulation (ROSC) and survival to hospital discharge in traumatic out-of-hospital cardiac arrest (TOHCA) patients without prehospital ROSC.

METHODS

We analyzed Korean nationwide data from the Out-of-Hospital Cardiac Arrest Surveillance, and included adult TOHCA patients without prehospital ROSC from January 2012 to December 2016. The primary outcome was sustained ROSC (>20 minutes). The secondary outcome was survival to discharge. Multivariate analysis was performed to investigate factors associated with the outcomes of TOHCA patients.

RESULTS

Among 142,905 cases of OHCA, 8,326 TOHCA patients were investigated. In multivariate analysis, male sex (odds ratio [OR], 1.326; 95% confidence interval [CI], 1.103-1.594; P=0.003), and an initial shockable rhythm (OR, 1.956; 95% CI, 1.113-3.439; P=0.020) were significantly associated with sustained ROSC. Compared with traffic crash, collision (OR, 1.448; 95% CI, 1.086-1.930; P=0.012) was associated with sustained ROSC. Fall (OR, 0.723; 95% CI, 0.589- 0.888; P=0.002) was inversely associated with sustained ROSC. Male sex (OR, 1.457; 95% CI, 1.026-2.069; P=0.035) and an initial shockable rhythm (OR, 4.724; 95% CI, 2.451-9.106; P<0.001) were significantly associated with survival to discharge. Metropolitan city (OR, 0.728; 95% CI, 0.541-0.980; P=0.037) was inversely associated with survival to discharge. Compared with traffic crash, collision (OR, 1.745; 95% CI, 1.125-2.708; P=0.013) was associated with survival to discharge.

CONCLUSION

Male sex, an initial shockable rhythm, and collision could be favorable factors for sustained ROSC, whereas fall could be an unfavorable factor. Male sex, non-metropolitan city, an initial shockable rhythm, and collision could be favorable factors in survival to discharge.

Improved survival of hospitalized patients with cardiac arrest due to coronary heart disease after implementation of post-cardiac arrest care: A population-based study

Post-cardiac arrest care was implemented in 2010 and has been shown to improve the survival of patients with coronary heart disease (CHD). However, the findings varied for different survival conditions.We conducted a retrospective longitudinal study of records from 2007 to 2013 in the National Health Insurance Research Database. We evaluated the differences in short-term (2-day and 7-day) and long-term (30-day and survival to discharge) survival after the implementation of post-cardiac arrest care and among age subgroups. We reviewed inpatient datasets in accordance with the International Classification of Disease Clinical Modification, 9th revision codes (ICD-9-CM). Eligible participants were identified as those with simultaneous diagnoses of cardiac arrest (ICD-9-CM codes: 427.41 or 427.5) and CHD (ICD-9-CM codes: 410-414). Multiple logistic regression was applied to establish the relationship between calendar year and survival outcomes.The odds of 2-day survival from 2011 to 2013 were higher than those from 2007 to 2010 (adjusted odds ratio [aOR]: 1.15; 95% confidence interval [CI]: 1.03-1.29). Similarly, the odds of 7-day survival from 2011 to 2013 were higher than those from 2007 to 2010 (aOR: 1.11; 95% CI: 1.01-1.22). Improvements in the odds of 2-day and 7-day survival were discovered only in patients <65 years old. Our data reinforce that short-term survival improved after implementation of post-cardiac arrest care. However, older age seemed to nullify the influence of post-cardiac arrest care on survival.

Survival rate variation among different types of hospitalized traumatic cardiac arrest: A retrospective and nationwide study

Studies regarding the prognostic factors for survival conditions and the proportions of survival to discharge among different types of hospitalized traumatic cardiac arrest (TCA) during the period of postresuscitation are limited.This nationwide study was designed to determine certain parameters and clarify the effect of various injuries on the survival of hospitalized TCA patients to discharge.Data were retrieved from the National Health Insurance Research Database (NHIRD) from 2007 to 2013 in Taiwan. We reviewed patients with a diagnosis of TCA using International Classification of Disease Clinical Modification, 9th revision codes (ICD-9-CM codes). Patients identified for analysis were simultaneously coded in traumatic etiology (ICD-9-CM codes: 800-999) and cardiac arrest (ICD-9-CM codes: 427.41 or 427.5). The determinants and effects of different types of injury on survival were evaluated by SPSS 22.0 (IBM, Armonk, NY).A total of 3481 cases of hospitalized TCA were selected from the NHIRD. The overall rate of survival to discharge was 22.1%. The results indicated a decreased adjusted odds ratio (aOR) of survival to discharge with higher numbers of organ failure (aOR: 0.82; 95% confidence interval [CI]: 0.73-0.92). Patients with ventricular fibrillation had a better discharge rate (aOR: 4.33; 95% CI: 3.29-5.70). Two parameters, transfer to another hospital and the number of intensive care unit beds, were positively correlated with survival. Compared with traffic accidents, different injuries associated with survival to discharge were identified; the aOR (95% CI) was 1.89 (1.12-3.19) for poisoning, 1.63 (1.13-2.36) for falls, and 2.00 (1.36-2.92) for drowning/suffocation.This study has shown that hospitalized TCA patients with multiple organ failure may be less likely to be discharged from the hospital. The presence of ventricular fibrillation rhythm on admission increased the odds of survival to discharge. In the phase of postcardiac arrest care, the number of intensive care unit beds and transfer to another hospital were positively correlated with survival. Those events attributed to traffic accidents have a much worse influence on the main outcome.

Gender and survival from out-of-hospital cardiac arrest: a New Zealand registry study

Objective

To determine the relationships between survival from all-cause out-of-hospital cardiac arrest (OHCA) and gender in New Zealand.

Methods

A retrospective observational study was conducted using data compliant with the Utstein guidelines from the St John New Zealand OHCA Registry for adult patients who were treated for an OHCA between 1 October 2013 and 30 September 2015. Univariate logistic regression was used to investigate factors associated with return of spontaneous circulation sustained to handover at hospital and survival to 30 days. Multivariate logistic regression models were used to investigate outcome differences in survival according to gender at 30 days postevent.

Results

Women survived to hospital handover in 29% of cases, which was not significantly different from men (31%). When adjusted for age, location, aetiology, initial rhythm and witnessed status, there was no significant difference in 30-day survival between men (16%) and women (13%) (adjusted OR 1.22, 95% CI (0.96 to 1.55), p=0.11).

Conclusion

No statistical differences were found in 30-day survival between genders when adjustments for unfavourable Utstein variables were accounted for.

Survival factors of hospitalized out-of-hospital cardiac arrest patients in Taiwan: A retrospective study

The chain of survival has been shown to improve the chances of survival for victims of cardiac arrest. Post-cardiac arrest care has been demonstrated to significantly impact the survival of out-of-hospital cardiac arrest (OHCA). How post-cardiac arrest care influences the survival of OHCA patients has been a main concern in recent years. The objective of this study was to assess the survival outcome of hospitalized OHCA patients and determine the factors associated with improved survival in terms of survival to discharge. We conducted a retrospective observational study by analyzing records from the National Health Insurance Research Database of Taiwan from 2007 to 2013. We collected cases with an International Classification of Disease Clinical Modification, 9^threvision primary diagnosis codes of 427.41 (ventricular fibrillation, VF) or 427.5 (cardiac arrest) and excluded patients less than 18 years old, as well as cases with an unknown outcome or a combination of traumatic comorbidities. We then calculated the proportion of survival to discharge among hospitalized OHCA patients. Factors associated with the dependent variable were examined by logistic regression. Statistical analysis was conducted using SPSS 22 (IBM, Armonk, NY). Of the 11,000 cases, 2,499 patients (22.7%) survived to hospital discharge. The mean age of subjects who survived to hospital discharge and those who did not was 66.7±16.7 and 71.7±15.2 years, respectively. After adjusting for covariates, neurological failure, cardiac comorbidities, hospital level, intensive care unit beds, transfer to another hospital, and length of hospital stay were independent predictors of improved survival. Cardiac rhythm on admission was a strong factor associated with survival to discharge (VF vs. non-VF: adjusted odds ratio: 3.51; 95% confidence interval: 3.06–4.01). In conclusion, cardiac comorbidities, hospital volume, cardiac rhythm on admission, transfer to another hospital and length of hospital stay had a significant positive association with survival to discharge in hospitalized OHCA patients in Taiwan.

The impact of sex and age on neurological outcomes in out-of-hospital cardiac arrest patients with targeted temperature management

Background

There are conflicting data regarding sex-based differences in the outcomes of out-of-hospital cardiac arrest (OHCA) patients, and whether the specific sex advantage is age-specific remains unclear. We assessed the impact of the interactions between sex and age on the neurological outcomes of OHCA patients receiving targeted temperature management (TTM).

Methods

Data collected from 2007 to 2012 for a multicenter, registry-based study of the Korean Hypothermia Network were analyzed. We used a multivariate logistic regression model with an interaction term (age × sex) as the final model for the outcomes. To evaluate the association between sex and outcome in specific age groups, all patients were divided into specific age subgroups, and the adjusted ORs and 95% CIs of good neurological outcomes for males were calculated for each age group. Finally, the ORs of a good neurological outcome for the specific age groups compared with the 50- to 59-year-old group were calculated for both sexes.

Results

In the interaction analysis, age was a negative prognostic factor (OR, 0.95 [95% CI, 0.93-0.98]), whereas sex was not associated with neurological outcomes (OR, 3.74 [95% CI, 0.85–16.35]), and reproductive age in females (age, < 50 years) was also not associated with good neurological outcomes. After the patients were divided into five age groups, sex was not an independent predictor of neurological outcomes across all age groups. Patients of both sexes aged < 40 years had significantly better outcomes than patients in the 50- to 59-year-old group (males, OR, 4.03 [95% CI, 1.86–8.73]; females, OR, 10.34 [95% CI, 1.99–53.85]). Males aged ≥ 70 years had significantly poorer neurological outcomes than those in the 50- to 59-year-old group (OR, 0.15 [95% CI, 0.07–0.32]), but this outcome was not observed for females (OR, 0.78 [95% CI, 0.20–3.14]).

Conclusions

Sex did not influence the neurological outcomes of TTM-treated OHCA patients. In contrast to the outcomes in males, the neurological outcomes of females worsened from 18 to 59 years of age and then remained constant.

Relationship between age and outcomes of comatose cardiac arrest survivors in a setting without withdrawal of life support

AIM OF THE STUDY

Previous studies on the relationship between age and outcomes after cardiac arrest were performed in settings where the majority of patients died after the withdrawal of life support (WLS). We examined the association between age and outcomes of comatose cardiac arrest survivors in a setting where WLS was not performed.

METHODS

This single-centre retrospective observational study included adult comatose cardiac arrest survivors treated with targeted temperature management. In Korea, WLS is not permitted unless the patient is pronounced brain-dead. The primary outcome was poor neurologic outcome at hospital discharge, defined as Cerebral Performance Categories scores of 3-5. The secondary outcomes were in-hospital and six-month mortalities.

RESULTS

A total of 534 patients were analysed. In multivariate analysis, age was not associated with in-hospital mortality (odds ratio [OR], 1.01; 95% confidence interval [CI], 0.99-1.02), but it was independently associated with neurologic outcome at hospital discharge (OR, 1.03; 95% CI, 1.02-1.05) and six-month mortality (OR, 1.05; 95% CI, 1.03-1.07). When age was categorised into 10-year intervals, age groups less than 61-70 years had significantly lower OR for poor neurologic outcome compared with the reference group (61-70 years), while the OR for poor neurologic outcome in age groups greater than 70 years did not differ from that in the reference group.

CONCLUSION

In a setting where WLS is not performed, we found that age was not associated with in-hospital mortality but was independently associated with neurologic outcome at hospital discharge and six-month mortality.

Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation

BACKGROUND

Good neurological outcome after cardiac arrest is difficult to achieve. Interventions during the resuscitation phase and treatment within the first hours after the event are critical. Experimental evidence suggests that therapeutic hypothermia is beneficial, and several clinical studies on this topic have been published. This review was originally published in 2009; updated versions were published in 2012 and 2016.

OBJECTIVES

We aimed to perform a systematic review and meta-analysis to assess the influence of therapeutic hypothermia after cardiac arrest on neurological outcome, survival and adverse events.

SEARCH METHODS

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 10); MEDLINE (1971 to May 2015); EMBASE (1987 to May 2015); the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1988 to May 2015); and BIOSIS (1989 to May 2015). We contacted experts in the field to ask for information on ongoing, unpublished or published trials on this topic.The original search was performed in January 2007.

SELECTION CRITERIA

We included all randomized controlled trials (RCTs) conducted to assess the effectiveness of therapeutic hypothermia in participants after cardiac arrest, without language restrictions. We restricted studies to adult populations cooled by any cooling method, applied within six hours of cardiac arrest.

DATA COLLECTION AND ANALYSIS

We entered validity measures, interventions, outcomes and additional baseline variables into a database. Meta-analysis was performed only for a subset of comparable studies with negligible heterogeneity. We assessed the quality of the evidence by using standard methodological procedures as expected by Cochrane and incorporated the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.

MAIN RESULTS

We found six RCTs (1412 participants overall) conducted to evaluate the effects of therapeutic hypothermia - five on neurological outcome and survival, one on only neurological outcome. The quality of the included studies was generally moderate, and risk of bias was low in three out of six studies. When we compared conventional cooling methods versus no cooling (four trials; 437 participants), we found that participants in the conventional cooling group were more likely to reach a favourable neurological outcome (risk ratio (RR) 1.94, 95% confidence interval (CI) 1.18 to 3.21). The quality of the evidence was moderate.Across all studies that used conventional cooling methods rather than no cooling (three studies; 383 participants), we found a 30% survival benefit (RR 1.32, 95% CI 1.10 to 1.65). The quality of the evidence was moderate.Across all studies, the incidence of pneumonia (RR 1.15, 95% CI 1.02 to 1.30; two trials; 1205 participants) and hypokalaemia (RR 1.38, 95% CI 1.03 to 1.84; two trials; 975 participants) was slightly increased among participants receiving therapeutic hypothermia, and we observed no significant differences in reported adverse events between hypothermia and control groups. Overall the quality of the evidence was moderate (pneumonia) to low (hypokalaemia).

AUTHORS' CONCLUSIONS

Evidence of moderate quality suggests that conventional cooling methods provided to induce mild therapeutic hypothermia improve neurological outcome after cardiac arrest, specifically with better outcomes than occur with no temperature management. We obtained available evidence from studies in which the target temperature was 34°C or lower. This is consistent with current best medical practice as recommended by international resuscitation guidelines for hypothermia/targeted temperature management among survivors of cardiac arrest. We found insufficient evidence to show the effects of therapeutic hypothermia on participants with in-hospital cardiac arrest, asystole or non-cardiac causes of arrest.

Effect of gender on outcome of out of hospital cardiac arrest in the Resuscitation Outcomes Consortium

INTRODUCTION

This study examined the relationship between gender and outcomes of non-traumatic out-of-hospital cardiac arrest (OHCA).

METHODS

All eligible, consecutive, non-traumatic Emergency Medical Services (EMS) treated OHCA patients in the Resuscitation Outcomes Consortium between December 2005 and May 2007. Patient age was analyzed as a continuous variable and stratified in two age cohorts: 15-45 and >55 years of age (yoa). Unadjusted and adjusted (based on Utstein characteristics) chi square tests and logistic regression models were employed to examine the relationship between gender, age, and survival outcomes.

RESULTS

This study enrolled 14,690 patients: of which 36.4% were women with a mean age of 68.3 and 63.6% of them men with a mean age of 64.2. Women survived to hospital discharge less often than men (6.4% vs. 9.1%, p<0.001); the unadjusted OR was 0.69, 95%CI: 0.60, 0.77 whereas when adjusted for all Utstein predictors the difference was not significant (OR: 1.16, 95%CI: 0.98, 1.36, p=0.07). The adjusted survival rate for younger women (15-45 yoa) was 11.1% vs. 9.8% for younger men (OR: 1.66, 95%CI: 1.04, 2.64, p=0.03) but no difference in discharge rates was observed in the >55 cohort (OR: 0.94, 95%CI: 0.78, 1.15, p=0.57).

CONCLUSIONS

Women who suffer OHCAs have lower rates of survival and have unfavourable Utstein predictors. When survival is adjusted for these predictors survival is similar between men and women except in younger women suggesting that age modifies the association of gender and survival from OHCA; a result that supports a protective hormonal effect among premenopausal women.

Differential survival for men and women from out-of-hospital cardiac arrest varies by age: results from the OPALS study

BACKGROUND

The effect of sex on survival in out-of-hospital cardiac arrest (OHCA) is controversial. Some studies report more favorable outcomes in women, while others suggest the opposite, citing disparities in care. Whether sex predicts differential age-specific survival is still uncertain.

OBJECTIVES

The objective was to study the sex-associated variation in survival to hospital discharge in OHCA patients as well as the relationship between age and sex for predicting survival.

METHODS

The Ontario Prehospital Advanced Life Support (OPALS) registry, collected in a large study of rapid defibrillation and advanced life support programs, is Utstein-compliant and has data on OHCA patients (1994 to 2002) from 20 communities in Ontario, Canada. All adult OHCAs not witnessed by emergency medical services (EMS) and treated during one of the three main OPALS phases were included. Clinically significant variables were chosen a priori (age, sex, witnessed arrest, initial cardiopulmonary resuscitation [CPR], shockable rhythm, EMS response interval, and OPALS study phase) and entered into a multivariable logistic regression model with survival to hospital discharge as the outcome, with sex and age as the primary risk factors. Fractional polynomials were used to explore the relationship between age and survival by sex.

RESULTS

A total of 11,479 (out of 20,695) OPALS cases met inclusion criteria and 10,862 (94.6%) had complete data for regression analysis. As a group, women were older than men (median age = 74 years vs. 69 years, p < 0.01), had fewer witnessed arrests (43% vs. 49%; p < 0.01), had fewer initial ventricular fibrillation/ventricular tachycardia rhythms (24% vs. 42%; p < 0.01), had a lower rate of bystander CPR (12% vs. 17%; p < 0.01), and had lower survival (1.7% vs. 3.2%; p < 0.01). Survival to hospital admission and return of spontaneous circulation did not differ between women and men (p > 0.05). The relationship between age, sex, and survival to hospital discharge could not be analyzed in a single regression model, as age did not have a linear relationship with survival for men, but did for women. Thus, age was kept as a continuous variable for women but was transformed for men using fractional polynomials [ln(age) + age(3) ]. In sex-stratified regression models, the adjusted probability of survival for women decreased as age increased (adjusted odds ratio = 0.88, 95% confidence interval = 0.81 to 0.96, per 5-year increase in age) while for men, the probability of survival initially increased with age until age 65 years and then decreased with increasing age. Women had a higher probability of survival until age 47 years, after which men maintained a higher probability of survival.

CONCLUSIONS

Overall OHCA survival for women was lower than for men in the OPALS study. Factors related to the sex differences in survival (rates of bystander CPR and shockable rhythms) may be modifiable. The probability of survival differed across age for men and women in a nonlinear fashion. This differential influence of age on survival for men and women should be considered in future studies evaluating survival by sex in OHCA population.

Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation

BACKGROUND

Good neurologic outcome after cardiac arrest is hard to achieve. Interventions during the resuscitation phase and treatment within the first hours after the event are critical. Experimental evidence suggests that therapeutic hypothermia is beneficial, and a number of clinical studies on this subject have been published. This review was originally published in 2009.

OBJECTIVES

We performed a systematic review and meta-analysis to assess the effectiveness of therapeutic hypothermia in patients after cardiac arrest. Neurologic outcome, survival and adverse events were our main outcomes. We aimed to perform individual patient data analysis, if data were available, and to form subgroups according to the cardiac arrest situation.

SEARCH METHODS

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2001, Issue 7); MEDLINE (1971 to July 2011); EMBASE (1987 to July 2011); CINAHL (1988 to July 2011); PASCAL (2000 to July 2011); and BIOSIS (1989 to July 2011). The original search was performed in January 2007.

SELECTION CRITERIA

We included all randomized controlled trials assessing the effectiveness of therapeutic hypothermia in patients after cardiac arrest, without language restrictions. Studies were restricted to adult populations cooled with any cooling method, applied within six hours of cardiac arrest.

DATA COLLECTION AND ANALYSIS

Validity measures, the intervention, outcomes and additional baseline variables were entered into a database. Meta-analysis was only done for a subset of comparable studies with negligible heterogeneity. For these studies, individual patient data were available.

MAIN RESULTS

We included four trials and one abstract reporting on 481 patients in the systematic review. The updated search resulted in no new studies to include. Quality of the included studies was good in three out of five studies. For the three comparable studies on conventional cooling methods all authors provided individual patient data. With conventional cooling methods, patients in the hypothermia group were more likely to reach a best cerebral performance categories (CPC) score of one or two (five point scale: 1 = good cerebral performance, to 5 = brain death) during the hospital stay (individual patient data; RR 1.55; 95% CI 1.22 to 1.96) and were more likely to survive to hospital discharge (individual patient data; RR 1.35; 95% CI 1.10 to 1.65) compared to standard post-resuscitation care. Across all studies, there was no significant difference in reported adverse events between hypothermia and control.

AUTHORS' CONCLUSIONS

Conventional cooling methods to induce mild therapeutic hypothermia seem to improve survival and neurologic outcome after cardiac arrest. Our review supports the current best medical practice as recommended by the International Resuscitation Guidelines.

Cardiac function and the proinflammatory cytokine response after recovery from cardiac arrest in swine

Increased levels of cytokines have been reported after resuscitation from cardiac arrest. We hypothesized that proinflammatory cytokines, released in response to ischemia/reperfusion, increase following resuscitation and play a role in post-cardiac arrest myocardial dysfunction. Ventricular fibrillation (VF) was induced by coronary occlusion in 20 swine. After 7 min of VF, resuscitation was performed as per guidelines. Plasma levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 were measured 15 min after the start of resuscitation in all animals and at intervals of 6 h in resuscitated animals. Intravascular pressures and cardiac output (CO) were also recorded. TNF-alpha abruptly increased after resuscitation, peaking at 15 min following return of spontaneous circulation, and declined to baseline levels after 3 h. IL-1beta increased more slowly, reaching a maximum 2 h after reperfusion. IL-6 concentrations were not significantly different from control values at any time point. Males demonstrated greater elevations of TNF-alpha and IL-1beta than females. Stroke work was significantly depressed at all time points with a nadir at 15-30 min after reperfusion, corresponding to the peak TNF-alpha values. The anti-TNF-alpha antibody infliximab attenuated the decrease in myocardial function observed 30 min after reperfusion. TNF-alpha increases during recovery from cardiac arrest are associated with depression of left ventricle (LV) function. The effect of TNF-alpha can be attenuated by anti-TNF-alpha antibodies.

Women of child-bearing age have better inhospital cardiac arrest survival outcomes than do equal-aged men

OBJECTIVES

Estrogen and progesterone improve neurologic outcomes in experimental models of cardiac arrest and stroke. Our objective was to determine whether women of child-bearing age are more likely than men to survive to hospital discharge after in-hospital cardiac arrest.

DESIGN

Prospective, observational study.

SETTING

Five hundred nineteen hospitals in the National Registry of Cardiopulmonary Resuscitation database.

PATIENTS

Patients included 95,852 men and women 15-44 yrs and 56 yrs or older with pulseless cardiac arrests from January 1, 2000 through July 31, 2008.

MEASUREMENTS AND MAIN RESULTS

Patients were stratified a priori by gender and age groups (15-44 yrs and > or =56 yrs). Fixed-effects regression conditioning on hospital was used to examine the relationship between age, gender, and survival outcomes. The unadjusted survival to discharge rate for younger women of child-bearing age (15-44 yrs) was 19% (940/4887) vs. 17% (1203/7025) for younger men (p = .013). The adjusted hospital discharge difference between these younger women and men was 2.8% (95% confidence interval, 1.0% to 4.6%; p = .002), and these younger women also had a 2.6% (95% confidence interval, 0.9% to 4.3%; p = .002) absolute increase in favorable neurologic outcome. For older women compared with men (> or =56 yrs), there were no demonstrable differences in discharge rates (18% vs. 18%; adjusted difference, -0.1%; 95% confidence interval, -0.9% to 0.6%; p = .68) or favorable neurologic outcome (14% vs. 14%; adjusted difference, -0.1%; 95% confidence interval, -0.7% to 0.5%; p = .74).

CONCLUSIONS

Women of child-bearing age were more likely than comparably aged men to survive to hospital discharge after in-hospital cardiac arrest, even after controlling for etiology of arrest and other important variables.

Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation

BACKGROUND

Good neurologic outcome after cardiac arrest is hard to achieve. Interventions during the resuscitation phase and treatment within the first hours after the event are critical. Experimental evidence suggests that therapeutic hypothermia is beneficial, and a number of clinical studies on this subject have been published.

OBJECTIVES

We performed a systematic review and meta-analysis to assess the effectiveness of therapeutic hypothermia in patients after cardiac arrest. Neurologic outcome, survival and adverse events were our main outcome parameters. We aimed to perform individual patient data analysis if data were available, and to from subgroups according to the cardiac arrest situation.

SEARCH STRATEGY

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2007 Issue 1); MEDLINE (1971 to January 2007); EMBASE (1987 to January 2007); CINAHL (1988 to January 2007); PASCAL (2000 to January 2007); and BIOSIS (1989 to January 2007).

SELECTION CRITERIA

We included all randomized controlled trials assessing the effectiveness of the therapeutic hypothermia in patients after cardiac arrest without language restrictions. Studies were restricted to adult populations cooled with any cooling method applied within six hours of cardiac arrest.

DATA COLLECTION AND ANALYSIS

Validity measures, the intervention, outcome parameters and additional baseline variables were entered into the database. Meta-analysis was only done for a subset of comparable studies with negligible heterogeneity. For these studies individual patient data were available.

MAIN RESULTS

Four trials and one abstract reporting on 481 patients were included in the systematic review. Quality of the included studies was good in three out of five included studies. For the three comparable studies on conventional cooling methods all authors provided individual patient data. With conventional cooling methods patients in the hypothermia group were more likely to reach a best cerebral performance categories score of one or two (CPC, five point scale; 1= good cerebral performance, to 5 = brain death) during hospital stay (individual patient data; RR, 1.55; 95% CI 1.22 to 1.96) and were more likely to survive to hospital discharge (individual patient data; RR, 1.35; 95% CI 1.10 to 1.65) compared to standard post-resuscitation care. Across all studies there was no significant difference in reported adverse events between hypothermia and control.

AUTHORS' CONCLUSIONS

Conventional cooling methods to induce mild therapeutic hypothermia seem to improve survival and neurologic outcome after cardiac arrest. Our review supports the current best medical practice as recommended by the International Resuscitation Guidelines.

Can brain natriuretic peptide predict outcome after cardiac arrest? An observational study

BACKGROUND

No accurate, independent biomarker has been identified that could reliably predict neurological outcome early after cardiac arrest. We speculated that brain natriuretic peptide (BNP) measured at hospital admission may predict patient outcome.

METHODS

BNP-levels were measured in 155 comatose cardiac arrest survivors (108 male, 58 years [IQR 49-68]) (median time to ROSC 11min; IQR 20-30) during a 6-year study period. Cardiovascular co-morbidities and resuscitation history were assessed according to the Utstein-style and patients were followed for 6-month neurological outcome measured by cerebral performance category (CPC) and survival.

RESULTS

Seventy patients (45%) suffered from unfavourable neurological outcome and 79 deaths (51%) occurred during the first 6 months. BNP was significantly associated with an adverse neurological outcome and mortality, independent of the prearrest health condition and cardiac arrest characteristics (median 60 pg/ml; IQR 10-230). Adjusted odds ratios for poor neurological outcome at 6 months were 1.14 (95% CI 0.51-2.53), 1.76 (95% CI 0.80-3.88) and 2.25 (95% CI 1.05-4.81), for increasing quartiles of BNP as compared to the lowest quartile. Adjusted odds ratios for mortality until 6 months were 1.09 (95% CI 0.35-3.40), 2.81 (0.80-9.90) and 4.7 (1.27-17.35) compared to the lowest quartile, respectively.

CONCLUSION

Brain natriuretic peptide levels on admission predict neurological outcome at 6 months and survival after cardiac arrest.