Gender Association with Incidence, Clinical Profile, and Outcome of Out-of-Hospital Cardiac Arrest: A Middle East Perspective.

Background: Out-of-hospital cardiac arrest (OHCA) is a leading cause of death worldwide. However, there is limited information on the outcome of the OHCA in the Middle East population, and limited studies have been carried out in the Arab Gulf countries. Hence, we aim to study the incidence and rate of survival in the OHCA setting and to assess the impact of gender on the clinical outcome following OHCA.
Methods: Retrospective analysis of a prospective registry of all eligible, consecutive, and nontraumatic adult patients who successfully resuscitated (return of spontaneous circulation) from "Cardiac Arrest" occurring outside the hospital, Hospitalized in Doha, Qatar from January 1991 to June 2010.
Results: A total of 41,453 consecutive patients were admitted during the study, of whom 987 (2.4%) had a diagnosis of OHCA. Among them, 269 (27.3%) were women and 718 (72.7%) were men. Although the mortality rate was higher in females than in males (65.4% vs. 57.7%, P = 0.03), the logistic regression analysis did not show gender as an independent predictor of death in this clinical setting.
Conclusion: In this sample of the state population, women who have OHCAs had a lower rate of survival, but gender was not an independent predictor of mortality following OHCA. Copyright:

INTRODUCTION

More than 400,000 cases of out-of-hospital cardiac arrest (OHCA) have been identified annually in the United States.[1] Many of these cases are due to coronary artery disease (CAD).[2] Multiple studies have shown substantial gender differences in CAD presentation, management, complications, and outcomes. Ischemic heart disease occurs in women 7–10 years later as opposed to men. Acute coronary syndrome (ACS) occurs three to four times more frequently in men than in women below 60 years of age, but above 75 years of age, the majority of patients are women.[3]

Women usually have atypical symptoms more frequently, up to 30% in some registries,[4] and tend to present later than men.[5] Women often have a greater chance of complications from bleeding with percutaneous coronary intervention (PCI). There is a major debate about poorer outcomes in women, and whether the poorer outcome is related to gender, old age, or more comorbidity among women with the ACS.[67]

Studies about the impact of gender on OHCA showed contradicting data; most of them are done in North America or Europe. There is no data available, to the best of our knowledge, in the Middle East population. In this study, we reviewed the impact of gender on the incidence, presentation, management, and outcomes of OHCA in Qatar.

METHODS

Design

This study is a retrospective analysis of a prospective registry of all eligible, consecutive, and nontraumatic adult patients who successfully resuscitated (return of spontaneous circulation) from “Cardiac Arrest” occurring outside the Hospital, Hospitalized in Doha, Qatar.

Statistical methods

The mean and standard deviations are calculated for continuous variables and frequencies with percentages are described for categorical variables. Student's t-tests are applied to see a significant difference between males and females for continuous variables and Chi-square tests for categorical variables. Gender distribution according to years is presented in the form of figures. Multivariate logistics regression analysis is applied to see associated factors to gender using enter method with significant factors at univariate analysis. Adjusted odds ratios are presented in the forest graph. P = 0.05 (two-tailed) is considered a statistically significant level. IBM Corp. Released 2019. IBM SPSS Statistics for Windows, version 26.0. Armonk, NY: IBM Corp. is used for the statistical analysis.

Study population

Adults successfully resuscitated (return of spontaneous circulation) from “Cardiac Arrest” occurring outside the hospital, which was presumed cardiac in origin, who were admitted to the department of cardiology of Hamad Medical Corporation HMC between 1991 and 2010.

Excluded: OHCA who died on the scene/in ambulance/brought in dead, OHCA secondary to noncardiac causes (metabolic and drug overdose).

RESULTS

A total of 41,453 patients were admitted to the cardiology department from January 1991 to June 2010; of these, 987 (2.4%) were admitted after sustaining OHCA. Among them, 269 (27.3%) were women and 718 (72.7%) were men.

Survival rate

Twenty percent of the total OHCA patients survived to hospital admission. About 40.2% of these patients survived to discharge. Hence, the survival rate is around 8%.

Temporal trend

The temporal trend in patients with OHCA according to gender is shown in Figure 1. The number of OHCA male patients steadily increased over time (59%), whereas the number of OHCA female patients showed a plateau (P = 0.03).

Figure 1

The temporal trend in patients with OHCA according to gender. OHCA, out-of-hospital cardiac arrest. OHCA: Out-of-Hospital Cardiac Arrest

Baseline clinical characteristics

Women9 were older (61 ± 14 years vs. 55 ± 15 years, P = 0.001), more likely to be Middle Eastern Arabs (77.7% vs. 48.6%, P = 0.001).

Preadmission comorbidities

Women were more likely to have diabetes mellitus (DM) (62.1% vs. 35.5%, P = 0.001), hypertension (HTN) (63.9% vs. 34.7%, P = 0.001), and chronic renal failure (12.3% vs. 5.6%, P = 0.001) and more obese (body mass index ≥30) (41.2% vs. 23.9%, P = 0.02) but less likely to be smokers (1.9% vs. 26.6%, P = 0.001) [Table 1].

Table 1

Risk factor profile and clinical characteristics

Clinical characteristics	Females (%) (n=269)	Males (%) (n=718)	P
Diabetes	62.1	35.5	0.001
Hypertension	63.9	34.7	0.001
Chronic renal failure	12.3	5.6	0.001
Obesity*	41.2	23.9	0.02
Smoking history	1.9	26.6	0.001
Dyslipidemia	13.4	18.2	0.07
Prior myocardial infarction	21.2	22	0.78

*Defined as BMI ≥30. BMI: Body mass index

Preceding symptoms

According to clinical profiles, dyspnea was a more common presenting symptom in female patients (36.4% vs. 20.5%, P = 0.001), whereas chest pain was more common in males (30.6% vs. 17.8%, P = 0.001) [Table 2].

Table 2

Incidence of preceding symptoms

Preceding symptoms	Females (%)	Males (%)	P
Chest pain	17.8	30.6	0.001
Dyspnea	36.4	20.5	0.001
Palpitations	4.1	3.1	0.43
Dizziness	1.5	2.9	0.20
Noncardiac complaint	3.7	2.8	0.45
Unknown or no preceding symptom	45	48.3	0.35

ST-segment elevation myocardial infarction

Of note, there was a significant difference in events of myocardial infarction in females versus males (13.8% vs. 36.1%, P = 0.001).

In-hospital management

It was noted that antithrombotic therapy was used less in a group of females (4.8% vs. 17.3%, P = 0.001). However, there was no significant difference in the use of evidence-based medications among patients [Table 3]. Furthermore, males were undergoing PCI and implantation of intra-aortic balloon pump more than females (13% vs. 5.2%, P = 0.001 and 4.7% vs. 0.7%, P = 0.003, respectively) [Table 4].

Table 3

The treatment of out-of-hospital cardiac arrest patient

Medications	Females (%)	Males (%)	P
Antiplatelet medications*	47.6	56.1	0.02
Anticoagulation+	27.9	35.9	0.02
Thrombolytic therapy	4.8	17.3	0.001
Antiarrhythmics	24.9	28.3	0.03
Use of inotropes	46.1	41.6	0.21

*Aspirin and/or clopidogrel; heparin/LMWH. LMWH: Low-molecular-weight heparins

Table 4

Percutaneous procedures done for out-of-hospital cardiac arrest patients

Procedures	Females (%)	Males (%)	P
Hemodynamic monitoring (swan ganz)	6.3	6.7	0.84
Temporary pacemaker	5.6	6.1	0.75
Any percutaneous procedure*	5.2	13	0.001
Intra aortic balloon pump	0.7	4.7	0.003

*Cath/PCI on admission/PCI before discharge/atherectomy. PCI: Percutaneous coronary intervention

Outcome

Although the mortality rate was higher in females than in males (65.4% vs. 57.7%, P = 0.03), the multivariate logistic regression analysis did not show gender as an independent predictor of death in this clinical setting.

DISCUSSION

Clinical characteristics

Survival outcomes from OHCA are generally poor with survival-to-discharge rates ranging from 3.0% to 16.3%.[8] In our analysis, the survival rate was 8% within the same range. Several studies have reported varying gender-specific survival results, and the findings have been somewhat contradictory.[910111213141516]

We found substantial male predominance among OHCA patients, consistent with previous studies.[1215] Female patients with OHCA were older, and more likely to have comorbid conditions (HTN, DM, and case report forms), which is also consistent with previous reports.[91215]

Trends

While the total number of OHCA patients increased overtime over the 20-year study period, the incidence per 100,000 population decreased [Figure 2]. The reason for this is due to the special nature of the Qatari population, which tripled since 2001 (600,000 population in 2001 and 1.6 million in 2010),[17] in fact, the main cause of this increase is the influx of a young healthy workforce into the state of Qatar; this age group is not only significantly lower than the average age of patients with OHCA at presentation, however, this is a preselected group of healthy individuals who had undergone preemployment health screening before arrival in the country [Figure 3]. Another potential reason for the decline in the in-hospital mortality rate in the last quarter (2006–2010) as compared with the period prior (1996–2005) is the increased use of the PCI in the latter group (more specifically in those with ST-segment elevation myocardial infarction [STEMI]), as this is the only treatment that has been shown to have a beneficial impact on survival. Improvements in multidisciplinary and intensive medical care are also likely contributors to this favorable trend.

Figure 2

The incidence of OHCA per 100,000 population. OHCA: Out-of-Hospital Cardiac Arrest

Figure 3

Gender distribution of Qatar population (2010)

Preceding symptoms and treatment

Data from the retrospective analysis of a prospective registry of all cardiac patients hospitalized post successfully resuscitated post-OHCA suggests that women who suffer an OHCA have fewer specific symptoms. The most common presenting symptom in male patients with OHCA was chest pain where female patients were more likely to have shortness of breath (not chest pain), and more male patients had STEMI on presentation and that is explained why female patients were less likely to be treated with antithrombotic therapy/PCI and were less likely to have Intra-Aortic Balloon Pump (IABP) insertion. However, among those with definite STEMI, both genders were treated the same. The ejection fraction was similar in males and females.

Survival

Like previous studies, survival outcomes also differed across genders in our study but when survival is adjusted for this imbalance in predictors of outcome, the gender difference in survival to discharge disappears [Figure 4].

Figure 4

Predictors of survival – Multivariate analysis

Limitations

The study is a 20-year registry during which treatments had changed. The quality of postarrest care includes the implementation of a comprehensive, multidisciplinary system of care with structured interventions including extracorporeal membrane oxygenation and hypothermia management has been shown to affect the outcome;[1819] which was not available at the time of the registry, however, it is conceivable that differences in-hospital care may lead to differences in long-term survival rates[20212223] after cardiac arrest. Hence, in future studies, it is important to assess the impact of postarrest care on OHCA outcomes. Another study limitation inherent in all studies of observational design is the accuracy of the findings of the study depends on the accuracy of the collected data, which are difficult to verify in a retrospective manner.

CONCLUSION

In this sample of the state population, women who have OHCA had a lower rate of survival, but gender was not an independent predictor of mortality following OHCA.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.