Influence of comorbidity on survival after out-of-hospital cardiac arrest in the United States

doi:10.1016/j.resuscitation.2019.09.030

Resuscitation

Volume 145, December 2019, Pages 21-25

https://doi.org/10.1016/j.resuscitation.2019.09.030 Get rights and content

Abstract

Aim

Association between survival rate and Elixhauser Comorbidity Index (ECI) among individuals suffering an out-of-hospital cardiac arrest (OHCA) in the United States (US).

Methods

We utilized the US National Emergency Department Sample (NEDS) dataset to retrospectively identify individuals experiencing OHCA between January 1, 2006 to December 31, 2015; using the International Classification of Diseases, Ninth Revision-Clinical Modification (ICD-9-CM) and Tenth Revision-Clinical Modification (ICD-10-CM) codes. Logistic regression analysis with twenty-nine ECIs as predictor variables were performed to compute for odds ratio (OR), after controlling for age and gender. Linear regression analysis performed to assess survival trend after clustering based on ECI. We also assessed the association of ECI with survival rate after stratifying patients based on cardiac rhythm (shockable versus non-shockable).

Results

We identified 1,282,520 (16.4%, survived-to-discharge) weighted observations presenting primarily after OHCA in the US during the study period. Annual percentage change (APC) in survival rate among OHCA patients with no ECI and those with >3 ECI was −1.53% (95% CI: −1.98% to −1.09%, P_trend < 0.001) and 1.2% (95% CI: 0.69%–1.7%, P_trend = 0.001), respectively. Adjusted OR for ECI was 1.31 (95% CI: 1.3–1.31, P < 0.001). Percentage change in the survival rate among shockable and non-shockable rhythm was 5.6% (95% CI: −3.9% to 15.13%, P_trend = 0.127) and 1.04% (95% CI: 0.01%–2.07%, P_trend = 0.05), respectively, with a unit increase in ECI.

Conclusion

In the US, OHCA patients with higher ECI have greater survival-to-discharge rate, demonstrating “comorbidity paradox”.

Introduction

Out-of-hospital cardiac arrest (OHCA) is a medical emergency with an estimated management cost of $455 billion annually in the United States (US).¹ Studies from the national patient population in Australia and Europe have demonstrated poor chances of survival after OHCA among patients with higher comorbidities.2, 3 While higher body mass index has shown to improve the survival rate among those experiencing sudden cardiac arrest (OHCA or in-hospital cardiac arrest [IHCA]).⁴ Furthermore, there is conflicting evidence with regards to the association between overall comorbidities and survival rate after cardiac arrest.3, 5 Due to significant variation in comorbidities⁶ and OHCA survival rate⁷ across the globe, we sought to analyze the association between comorbidity burden, as defined by Elixhauser Comorbidity Index (ECI), and survival rate after OHCA in the US population.

We utilized the US National Emergency Department Sample (NEDS) dataset to conduct a retrospective cross-sectional study to analyze the impact of ECI on survival-to-discharge rate among patients with OHCA in the US from January 1, 2006 to December 31, 2015. Additionally, we also assessed the impact of ECI after stratifying patients based on the cardiac rhythm (shockable versus non-shockable).

Section snippets

Data source

The NEDS, sponsored by the Healthcare Cost Utilization Project (HCUP), is the largest all-payer emergency department (ED) visit database in the US, and yields estimates from the hospital ED visits.² Thirty-seven states provide ED and inpatient visit data annually to constitute the NEDS. The strength of NEDS relies on is its geographical diversity (68.7% of the total US resident population and 78.2% of all ED visits) and consistency in data reporting. We analyzed the data in compliance with the

Results

We identified 1,282,520 weighted observations presenting to the ED primarily after OHCA in the US between January 1, 2006 and December 31, 2015; of whom only 209,643 (16.4%) survived-to-discharge after hospitalization. Mean (SD) of age for the study population was 65.8 (17.2) years; 62% were men. Median (IQR) ECI for the entire cohort was zero (0–2). Mean age among the study cohort increased with increasing ECI cluster (62 [17.8] years among ECI zero vs 65 [14.3] years among ECI > 3; P

Discussion

In our study from 1,282,520 OHCA patients in the US between January 1, 2006 to December 31, 2015, we report a significant decreasing trend in the survival-to-discharge rate among patients with no ECI, while the survival-to-discharge rate increased among those with >3 ECI. Additionally, higher ECI was associated with an increased survival-to-discharge rate after adjusting for age and gender, demonstrating “comorbidity paradox.”

Studies in the past have demonstrated findings contradictory to our

Conclusion

A higher survival-to-discharge rate is noted among OHCA with greater ECI when compared to no ECI, after adjusting for age and gender.

Financial disclosure

None.

Funding

None.

Conflict of interest

None.

Acknowledgement

We Thank Dr. Norman C Wang for his edits and all the authors confirm no financial assistance to complete this study. All authors have no disclosures.

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Data from 4225 OHCAs were analysed. EMS response time was shorter and the rate of attendance by EMS paramedics was higher in urban areas (p < 0.001 for both). Urban area was a prognostic factor for >24-h survival (odds ratio [OR] = 1.437, 95% confidence interval [CI]: 1.179–1.761). Age (OR = 0.986, 95% CI: 0.979–0.993). EMS response time (OR = 0.854, 95% CI: 0.811–0.898), cardiac arrest location (OR = 2.187, 95% CI: 1.707–2.795), attendance by paramedics (OR = 1.867, 95% CI: 1.483–2.347), and prehospital defibrillation (OR = 2.771, 95% CI: 2.154–3.556) were independent risk factors for survival to hospital discharge, although the influence of an urban area was not significant (OR = 1.211, 95% CI: 0.918–1.584).
Compared with rural areas, OHCA in urban areas are associated with a higher 24-h survival rate. Shorter EMS response time and a higher probability of being attended by paramedics were noted in urban areas. Although shorter EMS response time, younger age, public location, defibrillation by an automated external defibrillator, and attendance by Emergency Medical Technician-paramedics were associated with a higher rate of survival to hospital discharge, urban area was not an independent prognostic factor for survival to hospital discharge in OHCA patients.
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There were 2,852,347 ED episodes with a diagnosis of CA (50.5% primary diagnosis, 49.5% secondary diagnosis). Among patients with a secondary diagnosis of CA, ∼33% patients had a primary cardiac diagnosis, followed by infectious and respiratory diagnoses. The survival to ED discharge was 53.2%; lower for primary versus secondary CA diagnosis (20.4% vs 86.7%). The in-hospital survival rate for all CA was 28.7%, and was lower for primary versus secondary CA diagnosis (15.7% vs 41.9%). Survival to hospital discharge was highest in the age group of 41–60 years (33.0%) and was least among >80 years (20.9%). Survival was also noted to be lower among female patients (27.9% vs 29.2%) and in the winter months.
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Short paperInfluence of comorbidity on survival after out-of-hospital cardiac arrest in the United States

Abstract

Aim

Methods

Results

Conclusion

Introduction

Section snippets

Data source

Results

Discussion

Conclusion

Financial disclosure

Funding

Conflict of interest

Acknowledgement

Resuscitation

Resuscitation

Resuscitation

Mayo Clin Proc

The cost of prehospital cardiac arrest care

J Emerg Med Serv

Effect of body mass index on survival after sudden cardiac arrest

Clin Cardiol

Short paper
Influence of comorbidity on survival after out-of-hospital cardiac arrest in the United States