Mads Wissenberg

Association of national initiatives to improve cardiac arrest management with rates of bystander intervention and patient survival after out-of-hospital cardiac arrest

IMPORTANCEnOut-of-hospital cardiac arrest is a major health problem associated with poor outcomes. Early recognition and intervention are critical for patient survival. Bystander cardiopulmonary resuscitation (CPR) is one factor among many associated with improved survival.nnnOBJECTIVEnTo examine temporal changes in bystander resuscitation attempts and survival during a 10-year period in which several national initiatives were taken to increase rates of bystander resuscitation and improve advanced care.nnnDESIGN, SETTING, AND PARTICIPANTSnPatients with out-of-hospital cardiac arrest for which resuscitation was attempted were identified between 2001 and 2010 in the nationwide Danish Cardiac Arrest Registry. Of 29,111 patients with cardiac arrest, we excluded those with presumed noncardiac cause of arrest (nu2009=u20097390) and those with cardiac arrests witnessed by emergency medical services personnel (nu2009=u20092253), leaving a study population of 19,468 patients.nnnMAIN OUTCOMES AND MEASURESnTemporal trends in bystander CPR, bystander defibrillation, 30-day survival, and 1-year survival.nnnRESULTSnThe median age of patients was 72 years; 67.4% were men. Bystander CPR increased significantly during the study period, from 21.1% (95% CI, 18.8%-23.4%) in 2001 to 44.9% (95% CI, 42.6%-47.1%) in 2010 (Pu2009<u2009.001), whereas use of defibrillation by bystanders remained low (1.1% [95% CI, 0.6%-1.9%] in 2001 to 2.2% [95% CI, 1.5%-2.9%] in 2010; Pu2009=u2009.003). More patients achieved survival on hospital arrival (7.9% [95% CI, 6.4%-9.5%] in 2001 to 21.8% [95% CI, 19.8%-23.8%] in 2010; Pu2009<u2009.001). Also, 30-day survival improved (3.5% [95% CI, 2.5%-4.5%] in 2001 to 10.8% [95% CI, 9.4%-12.2%] in 2010; Pu2009<u2009.001), as did 1-year survival (2.9% [95% CI, 2.0%-3.9%] in 2001 to 10.2% [95% CI, 8.9%-11.6%] in 2010; Pu2009<u2009.001). Despite a decrease in the incidence of out-of-hospital cardiac arrests during the study period (40.4 to 34.4 per 100,000 persons in 2001 and 2010, respectively; Pu2009=u2009.002), the number of survivors per 100,000 persons increased significantly (Pu2009<u2009.001). For the entire study period, bystander CPR was positively associated with 30-day survival, regardless of witnessed status (30-day survival for nonwitnessed cardiac arrest, 4.3% [95% CI, 3.4%-5.2%] with bystander CPR and 1.0% [95% CI, 0.8%-1.3%] without; odds ratio, 4.38 [95% CI, 3.17-6.06]). For witnessed arrest the corresponding values were 19.4% (95% CI, 18.1%-20.7%) vs 6.1% (95% CI, 5.4%-6.7%); odds ratio, 3.74 (95% CI, 3.26-4.28).nnnCONCLUSIONS AND RELEVANCEnIn Denmark between 2001 and 2010, an increase in survival following out-of-hospital cardiac arrest was significantly associated with a concomitant increase in bystander CPR. Because of the co-occurrence of other related initiatives, a causal relationship remains uncertain.

Automated External Defibrillators Inaccessible to More Than Half of Nearby Cardiac Arrests in Public Locations During Evening, Nighttime, and Weekends

Background— Despite wide dissemination, use of automated external defibrillators (AEDs) in community settings is limited. We assessed how AED accessibility affected coverage of cardiac arrests in public locations. Methods and Results— We identified cardiac arrests in public locations (1994–2011) in terms of location and time and viewed them in relation to the location and accessibility of all AEDs linked to the emergency dispatch center as of December 31, 2011, in Copenhagen, Denmark. AED coverage of cardiac arrests was defined as cardiac arrests within 100 m (109.4 yd) of an AED and further categorized according to AED accessibility at the time of cardiac arrest. Daytime, evening, and nighttime were defined as 8 AM to 3:59 PM, 4 to 11:59 PM, and midnight to 7:59 AM, respectively. Of 1864 cardiac arrests in public locations, 61.8% (n=1152) occurred during the evening, nighttime, or weekends. Of 552 registered AEDs, 9.1% (n=50) were accessible at all hours, and 96.4% (n=532) were accessible during the daytime on all weekdays. Regardless of AED accessibility, 28.8% (537 of 1864) of all cardiac arrests were covered by an AED. Limited AED accessibility decreased coverage of cardiac arrests by 4.1% (9 of 217) during the daytime on weekdays and by 53.4% (171 of 320) during the evening, nighttime, and weekends. Conclusions— Limited AED accessibility at the time of cardiac arrest decreased AED coverage by 53.4% during the evening, nighttime, and weekends, which is when 61.8% of all cardiac arrests in public locations occurred. Thus, not only strategic placement but also uninterrupted AED accessibility warrant attention if public-access defibrillation is to improve survival after out-of-hospital cardiac arrest.

Return to Work in Out-of-Hospital Cardiac Arrest Survivors: A Nationwide Register-Based Follow-Up Study

Background— Data on long-term function of out-of-hospital cardiac arrest survivors are sparse. We examined return to work as a proxy of preserved function without major neurologic deficits in survivors. Methods and Results— In Denmark, out-of-hospital cardiac arrests have been systematically reported to the Danish Cardiac Arrest Register since 2001. During 2001–2011, we identified 4354 patients employed before arrest among 12 332 working-age patients (18–65 years), of whom 796 survived to day 30. Among 796 survivors (median age, 53 years [quartile 1–3, 46–59 years]; 81.5% men), 610 (76.6%) returned to work in a median time of 4 months [quartile 1–3, 1–19 months], with a median time of 3 years spent back at work. A total of 74.6% (N=455) remained employed without using sick leave during the first 6 months after returning to work. This latter proportion of survivors returning to work increased over time (66.1% in 2001–2005 versus 78.1% in 2006–2011; P=0.002). In multivariable Cox regression analysis, factors associated with return to work with ≥6 months of sustainable employment were as follows: (1) arrest during 2006–2011 versus 2001–2005, hazard ratio (HR), 1.38 (95% CI, 1.05–1.82); (2) male sex, HR, 1.48 (95% CI, 1.06–2.07); (3) age of 18 to 49 versus 50 to 65 years, HR, 1.32 (95% CI, 1.02–1.68); (4) bystander-witnessed arrest, HR, 1.79 (95% CI, 1.17–2.76); and (5) bystander cardiopulmonary resuscitation, HR, 1.38 (95% CI, 1.02–1.87). Conclusions— Of 30-day survivors employed before arrest, 76.6% returned to work. The percentage of survivors returning to work increased significantly, along with improved survival during 2001–2011, suggesting an increase in the proportion of survivors with preserved function over time.Background— Data on long-term function of out-of-hospital cardiac arrest survivors are sparse. We examined return to work as a proxy of preserved function without major neurologic deficits in survivors.nnMethods and Results— In Denmark, out-of-hospital cardiac arrests have been systematically reported to the Danish Cardiac Arrest Register since 2001. During 2001–2011, we identified 4354 patients employed before arrest among 12 332 working-age patients (18–65 years), of whom 796 survived to day 30. Among 796 survivors (median age, 53 years [quartile 1–3, 46–59 years]; 81.5% men), 610 (76.6%) returned to work in a median time of 4 months [quartile 1–3, 1–19 months], with a median time of 3 years spent back at work. A total of 74.6% (N=455) remained employed without using sick leave during the first 6 months after returning to work. This latter proportion of survivors returning to work increased over time (66.1% in 2001–2005 versus 78.1% in 2006–2011; P =0.002). In multivariable Cox regression analysis, factors associated with return to work with ≥6 months of sustainable employment were as follows: (1) arrest during 2006–2011 versus 2001–2005, hazard ratio (HR), 1.38 (95% CI, 1.05–1.82); (2) male sex, HR, 1.48 (95% CI, 1.06–2.07); (3) age of 18 to 49 versus 50 to 65 years, HR, 1.32 (95% CI, 1.02–1.68); (4) bystander-witnessed arrest, HR, 1.79 (95% CI, 1.17–2.76); and (5) bystander cardiopulmonary resuscitation, HR, 1.38 (95% CI, 1.02–1.87).nnConclusions— Of 30-day survivors employed before arrest, 76.6% returned to work. The percentage of survivors returning to work increased significantly, along with improved survival during 2001–2011, suggesting an increase in the proportion of survivors with preserved function over time.nn# CLINICAL PERSPECTIVE {#article-title-36}

Temporal Trends in Coverage of Historical Cardiac Arrests Using a Volunteer-Based Network of Automated External Defibrillators Accessible to Laypersons and Emergency Dispatch Centers

Background— Although increased dissemination of automated external defibrillators (AEDs) has been associated with more frequent AED use, the trade-off between the number of deployed AEDs and coverage of cardiac arrests remains unclear. We investigated how volunteer-based AED dissemination affected public cardiac arrest coverage in high- and low-risk areas. Methods and Results— All public cardiac arrests (1994–2011) and all registered AEDs (2007–2011) in Copenhagen, Denmark, were identified and geocoded. AED coverage of cardiac arrests was defined as historical arrests ⩽100 m from an AED. High-risk areas were defined as those with ≥1 arrest every 2 years and accounted for 1.0% of the total city area. Of 1864 cardiac arrests, 18.0% (n=335) occurred in high-risk areas throughout the study period. From 2007 to 2011, the number of AEDs and the corresponding coverage of cardiac arrests increased from 36 to 552 and from 2.7% to 32.6%, respectively. The corresponding increase for high-risk areas was from 1 to 30 AEDs and coverage from 5.7% to 51.3%, respectively. Since the establishment of the AED network (2007–2011), few arrests (n=55) have occurred ⩽100 m from an AED with only 14.5% (n=8) being defibrillated before the arrival of emergency medical services. Conclusions— Despite the lack of a coordinated public access defibrillation program, the number of AEDs increased 15-fold with a corresponding increase in cardiac arrest coverage from 2.7% to 32.6% over a 5-year period. The highest increase in coverage was observed in high-risk areas (from 5.7% to 51.3%). AED networks can be used as useful tools to optimize AED placement in community settings.

Accuracy of the ICD-10 discharge diagnosis for syncope

AIMSnAdministrative discharge codes are widely used in epidemiology, but the specificity and sensitivity of this coding is unknown and must be validated. We assessed the validity of the discharge diagnosis of syncope in administrative registers and reviewed the etiology of syncope after workup.nnnMETHODS AND RESULTSnTwo samples were investigated. One sample consisted of 5262 randomly selected medical patients. The other sample consisted of 750 patients admitted or seen in the emergency department (ED) for syncope (ICD-10: R55.9) in three hospitals in Denmark. All charts were reviewed for baseline characteristics and to confirm the presence/absence of syncope and to compare with the administrative coding. In a sample of 600 admitted patients 570 (95%) and of 150 patients from ED 140 (93%) had syncope representing the positive predictive values. Median age of the population was 69 years (IQR: ± 14). In the second sample of 5262 randomly selected medical patients, 75 (1.4%) had syncope, of which 47 were coded as R55.9 yielding a sensitivity of 62.7%, a negative predictive value of 99.5%, and a specificity of 99.9%.nnnCONCLUSIONnED and hospital discharge diagnostic coding for syncope has a positive predictive value of 95% and a sensitivity of 63%.

Temporal Differences in Out-of-Hospital Cardiac Arrest Incidence and Survival

Background— Understanding temporal differences in the incidence and outcomes of out-of-hospital cardiac arrest (OHCA) has important implications for developing preventative strategies and optimizing systems for OHCA care. Methods and Results— We studied 18u2009588 OHCAs of presumed cardiac origin in patients aged ≥18 years who received resuscitative efforts by emergency medical services (EMS) and were enrolled in the Cardiac Arrest Registry to Enhance Survival (CARES) from October 1, 2005, to December 31, 2010. We evaluated temporal variability in OHCA incidence and survival to hospital discharge. There was significant variability in the frequency of OHCA by hour of the day (P<0.001), day of the week (P<0.001), and month of the year (P<0.001), with the highest incidence occurring during the daytime, from Friday to Monday, in December. Survival to hospital discharge was lowest for OHCA that occurred overnight (from 11:01 PM to 7 AM; 7.1%) versus daytime (7:01 AM to 3 PM; 10.8%) or evening (3:01 PM to 11 PM; 11.3%; P<0.001) and during the winter (8.8%) versus spring (11.1%), summer (11.0%), or fall (10.0%; P<0.001). There was no difference in survival to hospital discharge between OHCAs that occurred on weekends and weekdays (9.5% versus 10.4%, P=0.06). After multivariable adjustment for age, sex, race, witness status, layperson resuscitation, first monitored cardiac rhythm, and emergency medical services response time, compared with daytime and spring, survival to hospital discharge remained lowest for OHCA that occurred overnight (odds ratio, 0.81; 95% confidence interval, 0.70–0.95; P=0.008) and during the winter (odds ratio, 0.81; 95% confidence interval, 0.70–0.94; P=0.006), respectively. Conclusions— There is significant temporal variability in the incidence of and survival after OHCA. The relative contribution of patient pathophysiology, likelihood of the OHCA being observed, and prehospital and hospital-based resuscitative factors deserves further exploration.

Out-of-hospital cardiac arrests in children and adolescents: Incidences, outcomes, and household socioeconomic status

BACKGROUNDnThere is insufficient knowledge of out-of-hospital cardiac arrest (OHCA) in the very young.nnnOBJECTIVESnThis nationwide study sought to examine age-stratified OHCA characteristics and the role of parental socioeconomic differences and its contribution to mortality in the young population.nnnMETHODSnAll OHCA patients in Denmark, ≤21 years of age, were identified from 2001 to 2010. The population was divided into infants (<1 year); pre-school children (1-5 years); school children (6-15 years); and high school adolescents/young adults (16-21 years). Multivariate logistic regression analyses were used to investigate associations between pre-hospital factors and study endpoints: return of spontaneous circulation and survival.nnnRESULTSnA total of 459 individuals were included. Overall incidence of OHCA was 3.3 per 100,000 inhabitants per year. The incidence rates for infants, pre-school children, school children and high school adolescents were 11.5, 3.5, 1.3 and 5.3 per 100,000 inhabitants. Overall bystander CPR rate was 48.8%, and for age groups: 55.4%, 41.2%, 44.9% and 63.0%, respectively. Overall 30-day survival rate was 8.1%, and for age groups: 1.4%, 4.5%, 16.1% and 9.3%, respectively. High parental education was associated with improved survival after OHCA (OR 3.48, CI 1.27-9.41). Significant crude difference in survival (OR 3.18, CI 1.22-8.34) between high household incomes vs. low household incomes was found.nnnCONCLUSIONnOHCA incidences and survival rates varied significantly between age groups. High parental education was found to be associated with improved survival after OHCA.

Survival After Out-of-Hospital Cardiac Arrest in Relation to Age and Early Identification of Patients With Minimal Chance of Long-Term Survival

Background— Survival after out-of-hospital cardiac arrest has increased during the last decade in Denmark. We aimed to study the impact of age on changes in survival and whether it was possible to identify patients with minimal chance of 30-day survival. Methods and Results— Using data from the nationwide Danish Cardiac Arrest Registry (2001─2011), we identified 21u2009480 patients ≥18 years old with a presumed cardiac-caused out-of-hospital cardiac arrest for which resuscitation was attempted. Patients were divided into 3 preselected age-groups: working-age patients 18 to 65 years of age (33.7%), early senior patients 66 to 80 years of age (41.5%), and late senior patients >80 years of age (24.8%). Characteristics in working-age patients, early senior patients, and late senior patients were as follows: witnessed arrest in 53.8%, 51.1%, and 52.1%; bystander cardiopulmonary resuscitation in 44.7%, 30.3%, and 23.4%; and prehospital shock from a defibrillator in 54.7%, 45.0%, and 33.8% (all P<0.05). Between 2001 and 2011, return of spontaneous circulation on hospital arrival increased: working-age patients, from 12.1% to 34.6%; early senior patients, from 6.4% to 21.5%; and late senior patients, from 4.0% to 15.0% (all P<0.001). Furthermore, 30-day survival increased: working-age patients, 5.8% to 22.0% (P<0.001); and early senior patients, 2.7% to 8.4% (P<0.001), whereas late senior patients experienced only a minor increase (1.5% to 2.0%; P=0.01). Overall, 3 of 9499 patients achieved 30-day survival if they met 2 criteria: had not achieved return of spontaneous circulation on hospital arrival and had not received a prehospital shock from a defibrillator. Conclusions— All age groups experienced a large temporal increase in survival on hospital arrival, but the increase in 30-day survival was most prominent in the young. With the use of only 2 criteria, it was possible to identify patients with a minimal chance of 30-day survival.

Survival after out-of-hospital cardiac arrest in relation to sex: A nationwide registry-based study☆

AIMnCrude survival has increased following an out-of-hospital cardiac arrest (OHCA). We aimed to study sex-related differences in patient characteristics and survival during a 10-year study period.nnnMETHODSnPatients≥12 years old with OHCA of a presumed cardiac cause, and in whom resuscitation was attempted, were identified through the Danish Cardiac Arrest Registry 2001-2010. A total of 19,372 patients were included.nnnRESULTSnOne-third were female, with a median age of 75 years (IQR 65-83). Compared to females, males were five years younger; and less likely to have severe comorbidities, e.g., chronic obstructive pulmonary disease (12.8% vs. 16.5%); but more likely to have arrest outside of the home (29.4% vs. 18.7%), receive bystander CPR (32.9% vs. 25.9%), and have a shockable rhythm (32.6% vs. 17.2%), all p<0.001. Thirty-day crude survival increased in males (3.0% in 2001 to 12.9% in 2010); and in females (4.8% in 2001 to 6.7% in 2010), p<0.001. Multivariable logistic regression analyses adjusted for patient characteristics including comorbidities, showed no survival difference between sexes in patients with a non-shockable rhythm (OR 1.00; CI 0.72-1.40), while female sex was positively associated with survival in patients with a shockable rhythm (OR 1.31; CI 1.07-1.59). Analyses were rhythm-stratified due to interaction between sex and heart rhythm; there was no interaction between sex and calendar-year.nnnCONCLUSIONSnTemporal increase in crude survival was more marked in males due to poorer prognostic characteristics in females with a lower proportion of shockable rhythm. In an adjusted model, female sex was positively associated with survival in patients with a shockable rhythm.

Association of Bystander Cardiopulmonary Resuscitation and Survival According to Ambulance Response Times after Out-of-Hospital Cardiac Arrest

Background: Bystander-initiated cardiopulmonary resuscitation (CPR) increases patient survival after out-of-hospital cardiac arrest, but it is unknown to what degree bystander CPR remains positively associated with survival with increasing time to potential defibrillation. The main objective was to examine the association of bystander CPR with survival as time to advanced treatment increases. Methods: We studied 7623 out-of-hospital cardiac arrest patients between 2005 and 2011, identified through the nationwide Danish Cardiac Arrest Registry. Multiple logistic regression analysis was used to examine the association between time from 911 call to emergency medical service arrival (response time) and survival according to whether bystander CPR was provided (yes or no). Reported are 30-day survival chances with 95% bootstrap confidence intervals. Results: With increasing response times, adjusted 30-day survival chances decreased for both patients with bystander CPR and those without. However, the contrast between the survival chances of patients with versus without bystander CPR increased over time: within 5 minutes, 30-day survival was 14.5% (95% confidence interval [CI]: 12.8–16.4) versus 6.3% (95% CI: 5.1–7.6), corresponding to 2.3 times higher chances of survival associated with bystander CPR; within 10 minutes, 30-day survival chances were 6.7% (95% CI: 5.4–8.1) versus 2.2% (95% CI: 1.5–3.1), corresponding to 3.0 times higher chances of 30-day survival associated with bystander CPR. The contrast in 30-day survival became statistically insignificant when response time was >13 minutes (bystander CPR vs no bystander CPR: 3.7% [95% CI: 2.2–5.4] vs 1.5% [95% CI: 0.6–2.7]), but 30-day survival was still 2.5 times higher associated with bystander CPR. Based on the model and Danish out-of-hospital cardiac arrest statistics, an additional 233 patients could potentially be saved annually if response time was reduced from 10 to 5 minutes and 119 patients if response time was reduced from 7 (the median response time in this study) to 5 minutes. Conclusions: The absolute survival associated with bystander CPR declined rapidly with time. Yet bystander CPR while waiting for an ambulance was associated with a more than doubling of 30-day survival even in case of long ambulance response time. Decreasing ambulance response time by even a few minutes could potentially lead to many additional lives saved every year.