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March 4, 2026npj Cardiovascular Health0 citationsOpen Access

Population-based risk adjusted outcomes for out-of-hospital cardiac arrest

EAEthan AbbottDBDavid G. BucklerKPKevin Petrozzo

Key Result

Out-of-hospital cardiac arrest survival to discharge was 14.9% among Medicare beneficiaries aged 65+, with 49.3% of US hospital regions demonstrating lower-than-expected risk-adjusted survival (mean SIR 0.91 ± 0.48).

Key Points

  • To investigate factors influencing variability in survival rates for out-of-hospital cardiac arrest across different US regions.
  • Analyzed 202,406 out-of-hospital cardiac arrest cases from Medicare claims (2013-2015)
  • Used logistic regression models to predict survival outcomes
  • Calculated standardized incidence ratios (SIRs) to assess regional performance
  • 49.3% of regions had lower-than-expected risk-adjusted survival
  • Only 4.4% of regions showed higher-than-expected survival rates
  • Overperforming regions were characterized by smaller populations and easier access to larger hospitals

Study Design

Type

Observational (n=202,406)

Multicenter

Yes

Structured PICO

What factors influence regional variability in risk-adjusted survival to hospital discharge for out-of-hospital cardiac arrest?

P
Population
202,406 Medicare Fee-For-Service beneficiaries aged ≥65 years old with out-of-hospital cardiac arrest (OHCA) across 205 hospital regions in the United States from 2013-2015.
O
Outcome
Survival to hospital dischargehard clinical

Significant regional disparities exist in OHCA survival across the US, with larger hospital capacity strongly associated with regional overperformance, highlighting the need for regionalized care approaches.

Main Result

Effect estimate: Mean SIR 0.91 ± 0.48; 49.3% regions underperforming (SIR<1), 4.4% regions overperforming (SIR>1)

Limitations

  • Use of Medicare claims data lacks clinical and prehospital detail compared to registries.
  • Study population limited to beneficiaries aged 65 and older, limiting generalizability to younger patients.
  • Survival defined as survival to hospital discharge among patients surviving to emergency department admission, possibly inflating survival rates.
  • Medicare population predominantly White (77.6%), limiting applicability to more diverse populations.
  • Hospital region definitions empirically derived may not precisely reflect real-world care patterns.
  • CARES registry and Medicare claims matching excluded unmatched encounters, limiting representativeness and possibly introducing selection bias.
  • Data from 2013-2015; however, national guidelines have remained constant, preserving relevance.
  • Statistical instability from small sample sizes or low expected survival counts in regions with low OHCA volumes
  • Drop in matched cohort size due to high specificity of the matching process and lack of hospital identifiers
  • Descriptive observation of publicly insured residents without statistical testing, limiting causal inference

Abstract

Abstract Out-of-hospital cardiac arrest (OHCA) impacts public health, with variable survival across the US. This study used a population-based risk adjustment model to understand factors influencing regional variability in OHCA survival to hospital discharge. We evaluated 202,406 OHCA cases from 2013-2015 Medicare Fee-For-Service claims across 205 hospital regions. A matched cohort from the Cardiac Arrest Registry to Enhance Survival (CARES) and Medicare claims was used to develop logistic regression models predicting survival. Standardized Incidence Ratios (SIRs) identified regions performing better or worse than expected. Of 205 regions, 101 (49.3%) demonstrated lower-than-expected risk-adjusted survival, while only 9 (4.4%) had higher-than-expected survival. Overperforming regions had smaller populations, higher proportions of residents aged 65 + , and more large hospitals (400+ beds). Hospitals with ≥100 beds were more likely in overperforming regions, while cardiac catheterization capability showed inverse association. These nationwide disparities highlight the need for targeted interventions and regionalized care approaches to improve survival rates.

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Cite This Study

Abbott et al. (2026) conducted an observational in Medicare beneficiaries aged 65 and older with out-of-hospital cardiac arrest (OHCA) across 205 hospital regions in the United States (n=202,406). Out-of-hospital cardiac arrest survival to discharge was 14.9% among Medicare beneficiaries aged 65+, with 49.3% of US hospital regions demonstrating lower-than-expected risk-adjusted survival (mean SIR 0.91 ± 0.48).

synapsesocial.com/papers/69a7cd1dd48f933b5eed928fhttps://doi.org/10.1038/s44325-026-00108-7
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