Regional variation in out-of-hospital cardiac arrest: Incidence and survival - A nationwide study of regions in Denmark.

AIM: Regional variation in incidence and survival after out-of-hospital cardiac arrest (OHCA) may be caused by many factors including differences in definitions and reporting. We examined regional differences in Denmark. METHODS: From the Danish Cardiac Arrest Registry we identified adult OHCA patients between 2009-2014 of presumed cardiac cause. Patients were grouped according to the five administrative/geographical regions of Denmark and survival was examined based on all arrest-cases (30-day survival percentage) and number of survivors per 100,000 inhabitants. RESULTS: We included 12,902 OHCAs of which 1550 (12.0 %) were alive 30 days after OHCA. No regional differences were observed in age, sex or comorbidities. Incidence of OHCA ranged from 32.9 to 42.4 per 100,000 inhabitants; 30-day survival percentages ranged from 8.5% to 13.8% and number of survivors per 100,000 inhabitants ranged from 3.5 to 5.9, across the regions. In one of the regions car-manned pre-hospital physicians were discontinued from 2011. Here, the incidence of OHCA per 100,000 inhabitants increased markedly from 37.1 in 2011 to 52.2 in 2014 and 30-day survival percentage decreased from 10.9 % in 2011 to 7.5 % in 2014; while the number of survivors per 100,000 inhabitants stagnated from 4.0 in 2011 to 3.9 in 2014. In comparison, survival increased in the other four regions. CONCLUSION: Differences in incidence and 30-day survival after OHCA were observed between the five regions of Denmark. Comparisons of survival should not only be based on survival percentages, but also on number of survivors of the background population as inclusion bias can influence survival outcomes.

Pre-hospital factors and survival after out-of-hospital cardiac arrest according to population density, a nationwide study.

AIM: This study aimed to examine the impact of population density on bystander cardiopulmonary resuscitation (CPR) and survival after out-of-hospital cardiac arrest (OHCA). METHODS: Through the Danish Cardiac Arrest Registry (2001-2013), OHCAs ≥18 years of presumed cardiac cause were identified, and divided according to the OHCA location in four population density groups (inhabitants/km2) based on urban/rural area-definitions: low (<300/km2), medium (300-1499/km2), high (1500-2999/km2), very high (>3000/km2). The association between population density, bystander cardiopulmonary resuscitation (CPR) and survival was examined using logistic regression, adjusted for age, sex, comorbitidies and calendar-year. RESULTS: 18,248 OHCAs were identified. Patients in areas of high compared to low population density were older, more often female, had more comorbidities, more witnessed arrests (very high: 59.6% versus low: 55.0%), shorter response time (very high: 10 min versus low: 14 min), but less bystander CPR (very high: 34.3% versus low: 45.1%). Thirty-day survival was higher in areas of higher population density (very high: 10.2% vs. low 5.3%), also in best-cases of witnessed arrests with bystander CPR and response time <10 min (very high: 33.6% versus low: 13.8%). The same trends were found in adjusted analyses with lower odds for bystander CPR (odds ratio [OR] 0.55 95% confidence interval [CI] 0.46-0.66) and higher odds for 30-day survival (OR 2.78, 95%CI 1.95-3.96) in the highest population density areas compared to low. CONCLUSIONS: Having an OHCA in higher populated areas were found associated with less bystander CPR, but higher survival. Identification of area-related factors can help target future pre-hospital care.

Out-of-hospital cardiac arrest: 30-day survival and 1-year risk of anoxic brain damage or nursing home admission according to consciousness status at hospital arrival.

AIM: To investigate the association between consciousness status at hospital arrival and long-term outcomes in out-of-hospital cardiac arrest (OHCA) patients. METHODS: OHCAs between 18-100 years of age were identified from the Danish Cardiac Arrest Registry during 2005-2014. Patients with return of spontaneous circulation (ROSC) or ongoing cardiopulmonary resuscitation (CPR) at hospital arrival were included. Thirty-day survival was evaluated using Kaplan-Meier estimates. Risk of anoxic brain damage or nursing home admission and return to work among 30-day survivors were evaluated using Aalen-Johansen estimates and cause-specific Cox regression. RESULTS: Upon hospital arrival of 13,953 OHCA patients, 776 (5.6%) had ROSC and were conscious (Glasgow Coma Score [GCS]>8), 5205 (37.3%) had ROSC, but were comatose (GCS ≤ 8), and 7972 (57.1%) had ongoing CPR. Thirty-day survival according to status at hospital arrival among patients that were conscious, comatose, or had ongoing CPR was 89.0% (95% confidence interval [CI] 86.8%-91.2%), 39.0% (95% CI 37.6%-40.3%), and 1.2% (95% CI 1.0%-1.4%), respectively. Among 30-day survivors, 1-year risks of new onset anoxic brain damage or nursing home admission according to consciousness status were 2.4% (95% CI 1.2%-3.6%), 12.9% (95% CI 11.4%-14.3%), and 19.4% (95% CI 11.3%-27.4%), respectively. Among 30-day working-age survivors, more than 65% in each group returned to work within 5 years. CONCLUSION: Consciousness status at hospital arrival was strongly associated with 30-day survival in OHCA patients. Among 30-day survivors, a minority was diagnosed with anoxic brain damage or admitted to a nursing home and the majority returned to work independent of consciousness status at hospital arrival.

Automated external defibrillator accessibility is crucial for bystander defibrillation and survival: A registry-based study.

AIMS: Optimization of automated external defibrillator (AED) placement and accessibility are warranted. We examined the associations between AED accessibility, at the time of an out-of-hospital cardiac arrest (OHCA), bystander defibrillation, and 30-day survival, as well as AED coverage according to AED locations. METHODS: In this registry-based study we identified all OHCAs registered by mobile emergency care units in Copenhagen, Denmark (2008-2016). Information regarding registered AEDs (2007-2016) was retrieved from the nationwide Danish AED Network. We calculated AED coverage (AEDs located ≤200 m route distance from an OHCA) and, according to AED accessibility, the likelihoods of bystander defibrillation and 30-day survival. RESULTS: Of 2500 OHCAs, 22.6% (n = 566) were covered by a registered AED. At the time of OHCA, <50% of these AEDs were accessible (n = 276). OHCAs covered by an accessible AED were nearly three times more likely to receive bystander defibrillation (accessible: 13.8% vs. inaccessible: 4.8%, p < 0.001) and twice as likely to achieve 30-day survival (accessible: 28.8% vs. inaccessible: 16.4%, p < 0.001). Among bystander-witnessed OHCAs with shockable heart rhythms (accessible vs. inaccessible AEDs), bystander defibrillation rates were 39.8% vs. 20.3% (p = 0.01) and 30-day survival rates were 72.7% vs. 44.1% (p < 0.001). Most OHCAs were covered by AEDs at offices (18.6%), schools (13.3%), and sports facilities (12.9%), each with a coverage loss >50%, due to limited AED accessibility. CONCLUSIONS: The chance of a bystander defibrillation was tripled, and 30-day survival nearly doubled, when the nearest AED was accessible, compared to inaccessible, at the time of OHCA, underscoring the importance of unhindered AED accessibility.

Severity of ischemic heart disease and presenting rhythm in patients with out-of-hospital cardiac arrest.

INTRODUCTION: Ischemic heart disease (IHD) is associated with a shockable rhythm in out-of-hospital cardiac arrest (OHCA). However, the impact of IHD severity on first recorded rhythm is unknown. We hypothesized that the strength of the association between IHD and shockable rhythm increases with increasing IHD severity. METHODS: OHCA patients were identified in the Danish Cardiac Arrest Registry (2001-2014). Population-based registries were used to identify chronic diseases, drug prescriptions and cardiac procedures such as coronary angiography (CAG), percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG). Severity of IHD was categorized as 1) No diagnosis of IHD, 2) IHD without previous CAG, PCI or CABG, 3) IHD with CAG, 4) IHD with PCI, and 5) IHD with CABG. Adjusted odds ratios (ORs) for a shockable rhythm was computed using multivariable logistic regression. RESULTS: Of 34,749 patients with OHCA, 6325 (18.2%) patients had a diagnosis of IHD. The prevalence of a shockable rhythm was higher for patients with a previous diagnosis of IHD (25.6%) and for those with previous CAG (33.3%), PCI (36.4%) or CABG (34.0%) when compared to patients without IHD (21.2%). IHD was associated with shockable rhythm (OR = 1.69, 95%CI 1.55-1.85) when compared to patients without IHD. The association with shockable rhythm was higher for patients with a history of CAG (OR = 1.92, 95%CI 1.67-2.20) and PCI (OR = 1.93, 95%CI 1.67-2.23), but similar in patients with CABG (OR = 1.69, 95%CI 1.37-2.10). CONCLUSION: IHD was associated with a shockable rhythm, with a moderate increase in the association in patients with a CAG or PCI procedure.

Associations of serum potassium levels with mortality in chronic heart failure patients.

AIMS: Medication prescribed to patients suffering from chronic heart failure carries an increased risk of impaired potassium homeostasis. We examined the relation between different levels of serum potassium and mortality among patients with chronic heart failure. METHODS AND RESULTS: From Danish National registries, we identified 19 549 patients with a chronic heart failure diagnosis who had a measurement of potassium within minimum 90 days after initiated medical treatment with loop diuretics and angiotensin converting enzyme inhibitors or angiotensin-II receptor blockers. All-cause mortality was examined according to eight predefined potassium levels: 2.8-3.4 mmol/L, 3.5-3.8 mmol/L, 3.9-4.1 mmol/L, 4.2-4.4 mmol/L, 4.5-4.7 mmol/L, 4.8-5.0 mmol/L, 5.1-5.5 mmol/L, and 5.6-7.4 mmol/L. Follow-up was 90 days from potassium measurement. We estimated the risk of all-cause mortality using multivariable adjusted Cox proportional hazard model, with normal serum potassium level at 4.2-4.4 mmol/L as reference. After 90 days, the mortality in the eight strata was 14.4, 8.0, 6.3, 5.0, 5.8, 7.9, 10.3, and 21.1% respectively. In multivariable adjusted analysis, patients with potassium levels of 2.8-3.4 mmol/L [hazard ratio (HR): 3.16; confidence interval (CI): 2.43-4.11], 3.5-3.8 mmol/L (HR: 1.62; CI: 1.31-1.99), 3.9-4.1 mmol/L (HR: 1.29; CI: 1.08-1.55), 4.8-5.0 mmol/L (HR: 1.34; CI: 1.10-1.63), 5.1-5.5 mmol/L (HR: 1.60; CI: 1.29-1.97), and 5.6-7.4 mmol/L (HR: 3.31; CI: 2.61-4.20) had an increased risk of all-cause mortality. CONCLUSION: Levels within the lower and upper levels of the normal serum potassium range (3.5-4.1 mmol/L and 4.8-5.0 mmol/L, respectively) were associated with a significant increased short-term risk of death in chronic heart failure patients. Likewise, potassium below 3.5 mmol/L and above 5.0 mmol/L was also associated with increased mortality.