LONG-TERM MORTALITY, READMISSION AND FUNCTIONAL OUTCOMES AMONG HOSPITAL SURVIVORS OF OUT-OF-HOSPITAL CARDIAC ARREST

Abstract

BACKGROUND Out-of-hospital cardiac arrest (OHCA) is associated with poor in-hospital outcomes. However, the impact of pre- and in-hospital factors on long-term survival, healthcare utilization and functional outcomes is ill-defined, mainly related to challenges combining disparate data sources. METHODS AND RESULTS Adult non-traumatic OHCAs from the British Columbia Cardiac Arrest Registry (Jan 2009 to Dec 2016) were linked to provincial datasets comprising co-morbidities, medications, cardiac procedures, mortality, and hospital admission and discharge. Among hospital-discharge survivors, the 3-year endpoint of mortality or mortality and all-cause readmission was examined using the Kaplan-Meier (KM) method and multivariable Cox model for predictors. Functional status, defined as the use of publicly funded home care and community services (HCCS) within 1-year post-discharge, was evaluated by logistic regression. Of 10,876 linked, emergency medical services (EMS)-treated OHCAs, 3230 were admitted to hospital. Compared to hospital non-survivors (n=1905), hospital survivors (n=1325) had fewer co-morbidities and were more likely to have favorable resuscitation characteristics (shockable rhythm, witnessed arrest, bystander CPR). Among hospital survivors, 78.6% were treated with mechanical ventilation, 69.1% received coronary angiography, 37.5% and 10.3% were revascularized via PCI or CABG, respectively, and 24.8% received an intracardiac defibrillator (ICD) prior to discharge. At 3 years post-discharge, the estimated Kaplan-Meier (KM) survival rate was 84.1% [95% CI: 81.7%, 86.1%] and freedom from death and all-cause readmission was 31.8% (CI: 29.0%, 34.7%) (Figure). Predictors of post-discharge 3-year mortality included: older age, history of heart failure (HF), history of chronic kidney disease (CKD), non-public cardiac arrest location, initial non-shockable rhythm, and concomitant HF on admission; predictors of a lower risk of death included EMS witnessed arrest (HR 0.61, 95% CI: 0.40, 0.93), revascularization (HR 0.42, 95% CI: 0.28, 0.63), or ICD implant (HR 0.44, 95% CI: 0.27, 0.71). After excluding patients receiving HCCS prior to OHCA, 23.7% (n=289/1218) had poor functional outcome. Predictors of poor functional outcome included age > 75, female sex, history of CKD, non-public cardiac arrest location, initial non-shockable rhythm, and mechanical ventilation; ICD implantation was associated with a lower risk of poor functional status (OR 0.55, 95% CI: 0.38, 0.81). CONCLUSION While the long-term death or readmission risk persists even among OHCA hospital survivors, only 1 in 4 survivors accessed HCCS 1-year post-discharge, indicating overall good functional outcome. These results show that post-discharge outcomes are strongly influenced by both pre- and in-hospital factors, and supports efforts to improve care processes to increase survival to hospital discharge. Out-of-hospital cardiac arrest (OHCA) is associated with poor in-hospital outcomes. However, the impact of pre- and in-hospital factors on long-term survival, healthcare utilization and functional outcomes is ill-defined, mainly related to challenges combining disparate data sources. Adult non-traumatic OHCAs from the British Columbia Cardiac Arrest Registry (Jan 2009 to Dec 2016) were linked to provincial datasets comprising co-morbidities, medications, cardiac procedures, mortality, and hospital admission and discharge. Among hospital-discharge survivors, the 3-year endpoint of mortality or mortality and all-cause readmission was examined using the Kaplan-Meier (KM) method and multivariable Cox model for predictors. Functional status, defined as the use of publicly funded home care and community services (HCCS) within 1-year post-discharge, was evaluated by logistic regression. Of 10,876 linked, emergency medical services (EMS)-treated OHCAs, 3230 were admitted to hospital. Compared to hospital non-survivors (n=1905), hospital survivors (n=1325) had fewer co-morbidities and were more likely to have favorable resuscitation characteristics (shockable rhythm, witnessed arrest, bystander CPR). Among hospital survivors, 78.6% were treated with mechanical ventilation, 69.1% received coronary angiography, 37.5% and 10.3% were revascularized via PCI or CABG, respectively, and 24.8% received an intracardiac defibrillator (ICD) prior to discharge. At 3 years post-discharge, the estimated Kaplan-Meier (KM) survival rate was 84.1% [95% CI: 81.7%, 86.1%] and freedom from death and all-cause readmission was 31.8% (CI: 29.0%, 34.7%) (Figure). Predictors of post-discharge 3-year mortality included: older age, history of heart failure (HF), history of chronic kidney disease (CKD), non-public cardiac arrest location, initial non-shockable rhythm, and concomitant HF on admission; predictors of a lower risk of death included EMS witnessed arrest (HR 0.61, 95% CI: 0.40, 0.93), revascularization (HR 0.42, 95% CI: 0.28, 0.63), or ICD implant (HR 0.44, 95% CI: 0.27, 0.71). After excluding patients receiving HCCS prior to OHCA, 23.7% (n=289/1218) had poor functional outcome. Predictors of poor functional outcome included age > 75, female sex, history of CKD, non-public cardiac arrest location, initial non-shockable rhythm, and mechanical ventilation; ICD implantation was associated with a lower risk of poor functional status (OR 0.55, 95% CI: 0.38, 0.81). While the long-term death or readmission risk persists even among OHCA hospital survivors, only 1 in 4 survivors accessed HCCS 1-year post-discharge, indicating overall good functional outcome. These results show that post-discharge outcomes are strongly influenced by both pre- and in-hospital factors, and supports efforts to improve care processes to increase survival to hospital discharge.