Assertive community treatment for high-utilizing alcohol misuse patients: a before-and-after cohort study protocol.

BACKGROUND: The challenge posed by Alcohol-Related Frequent Attenders (ARFAs) in Emergency Departments (EDs) is growing in Singapore, marked by limited engagement with conventional addiction treatment pathways. Recognizing this gap, this study aims to explore the potential benefits of Assertive Community Treatment (ACT) - an innovative, community-centered, harm-reduction strategy-in mitigating the frequency of ED visits, curbing Emergency Medical Services (EMS) calls, and uplifting health outcomes across a quartet of Singaporean healthcare institutions. METHODS: Employing a prospective before-and-after cohort design, this investigation targeted ARFAs aged 21 years and above, fluent in English or Mandarin. Eligibility was determined by a history of at least five ED visits in the preceding year, with no fewer than two due to alcohol-related issues. The study contrasted health outcomes of patients integrated into the ACT care model versus their experiences under the exclusive provision of standard emergency care across Hospitals A, B, C and D. Following participants for half a year post-initial assessment, the evaluation metrics encompassed socio-demographic factors, ED, and EMS engagement frequencies, along with validated health assessment tools, namely Christo Inventory for Substance-misuse Services (CISS) scores, University of California, Los Angeles (UCLA) Loneliness scores, and Centre for Epidemiologic Studies Depression Scale Revised (CESD-R-10) scores. DISCUSSION: Confronted with intricate socio-economic and medical challenges, the ARFA cohort often grapples with heightened vulnerabilities in relation to alcohol misuse. Pioneering the exploration of ACT's efficacy with ARFAs in a Singaporean context, our research is anchored in a patient-centered approach, designed to comprehensively address these multifaceted clinical profiles. While challenges, like potential high attrition rates and sporadic data collection, are anticipated, the model's prospective contribution towards enhancing patient well-being and driving healthcare efficiencies in Singapore is substantial. Our findings have the potential to reshape healthcare strategies and policy recommendations. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04447079. Initiated on 25 June 2020.

Improved Out-of-Hospital Cardiac Arrest Survival with a Comprehensive Dispatcher-Assisted CPR Program in a Developing Emergency Care System.

OBJECTIVE: Out-of-hospital cardiac arrest (OHCA) is associated with poor survival. Studies have demonstrated improved survival with early bystander cardiopulmonary resuscitation (BCPR). This study evaluated the impact of a dispatcher-assisted CPR (DA-CPR) program on BCPR rate and outcomes of OHCA in a developing emergency medical services (EMS) system setting. METHODS: Data were extracted from the national cardiac arrest registry. A before-after analysis was performed between OHCA cases with cardiac etiology conveyed by EMS from April 2010-June 2012 (pre-intervention) and July 2012-December 2015 (post-intervention). Primary outcomes were survival-to-discharge/30 days post-arrest and favorable cerebral performance (Glasgow-Pittsburgh cerebral performance categories 1 and 2). RESULTS: 6365 OHCA cases were analyzed with 2129 in the pre-intervention and 4236 in the post-intervention group. In the post-intervention group, there was an increase in BCPR rates from 24.8% to 53.8% (p < 0.001), adjusted OR 3.67 (aOR; 95%CI: 3.26-4.13). OHCA outcomes also improved with survival-to-discharge rates increasing from 3.0%-4.5% (p < 0.01), aOR 2.10 (95%CI: 1.40-3.17) and favorable cerebral performance increasing from 1.6% to 2.7% (p < 0.05), aOR 2.82 (95%CI: 1.65-4.82). In patients with initial shockable rhythm, BCPR without dispatcher assistance was associated with significantly higher odds of survival-to-discharge (aOR 1.67, 95%CI: 1.06-2.64) and favorable cerebral performance (aOR 2.32, 95%CI: 1.26-4.27) compared to no BCPR. CONCLUSION: Our study showed that a simplified DA-CPR program can be successfully implemented in a developing EMS system and can contribute to higher BCPR rate and in turn, improve OHCA survival. Future studies can examine bystanders' characteristics and quality of the CPR performed to understand their impact on survival.

Emergency medical dispatch services across Pan-Asian countries: a web-based survey.

BACKGROUND: Dispatch services (DS's) form an integral part of emergency medical service (EMS) systems. The role of a dispatcher has also evolved into a crucial link in patient care delivery, particularly in dispatcher assisted cardio-pulmonary resuscitation (DACPR) during out-of-hospital cardiac arrest (OHCA). Yet, there has been a paucity of research into the emerging area of dispatch science in Asia. This paper compares the characteristics of DS's, and state of implementation of DACPR within the Pan-Asian Resuscitation Outcomes (PAROS) network. METHODS: A cross-sectional descriptive survey addressing population characteristics, DS structures and levels of service, state of DACPR implementation (including protocols and quality improvement programs) among PAROS DS's. RESULTS: 9 DS's responded, representing a total of 23 dispatch centres from 9 countries that serve over 80 million people. Most PAROS DS's operate a tiered dispatch response, have implemented medical oversight, and tend to be staffed by dispatchers with a predominantly medical background. Almost all PAROS DS's have begun tracking key EMS indicators. 77.8% (n = 7) of PAROS DS's have introduced DACPR. Of the DS's that have rolled out DACPR, 71.4% (n = 5) provided instructions in over one language. All DS's that implemented DACPR and provided feedback to dispatchers offered feedback on missed OHCA recognition. The majority of DS's (83.3%; n = 5) that offered DACPR and provided feedback to dispatchers also implemented corrective feedback, while 66.7% (n = 4) offered positive feedback. Compression-only CPR was the standard instruction for PAROS DS's. OHCA recognition sensitivity varied widely in PAROS DS's, ranging from 32.6% (95% CI: 29.9-35.5%) to 79.2% (95% CI: 72.9-84.4%). Median time to first compression ranged from 120 s to 220 s. CONCLUSIONS: We found notable variations in characteristics and state of DACPR implementation between PAROS DS's. These findings will lay the groundwork for future DS and DACPR studies in the PAROS network.

Nationwide Alcohol-related visits In Singapore's Emergency departments (NAISE): A retrospective population-level study from 2007 to 2016.

INTRODUCTION: Excessive alcohol consumption is associated with increased morbidity and mortality, and its societal impact is substantial. The Nationwide Alcohol-related visits In Singapore Emergency departments study aims to characterise trends in ED visits involving acute and chronic alcohol consumption between 2007 and 2016. METHODS: Data from the Singapore Ministry of Health, comprising all ED visits in Singapore from 2007 to 2016, were used. The data were aggregated by year and analysed for changes in prevalence and rates of ED visits for acute and chronic alcohol consumption, broken down by age, gender and ethnicity. RESULTS: Over the study period, the number of ED visits involving alcohol consumption increased 98.3%, from 2236 in 2007 to 4433 in 2016. During the same period, the rate per 100 000 population increased 62.4% from 48.7 to 79.1, and total ED-related costs rose by 140%, from 528 680 to 1 269 638 SGD. The increase in alcohol-related visits rates and costs was higher than non-alcohol-related visits rates and costs, which increased by 12.1% and 115% respectively. While trends in acute and chronic alcohol-related ED visits stayed stable amongst women, they rose substantially in men. Older men aged 50-69 show the highest rates and rate of increase for both acute and chronic alcohol-related ED visits. DISCUSSION AND CONCLUSIONS: Alcohol-related visits contributed disproportionately to the increasing number of ED visits in Singapore between 2007 and 2016. Older men form the demographic with the highest rates and increase in rates of alcohol-related ED visits and form a potential group for targeted intervention.

Why Are Some Male Alcohol Misuse Disorder Patients High Utilisers of Emergency Health Services? An Asian Qualitative Study.

BACKGROUND: Certain alcohol misuse patients heavily utilise the Emergency Department (ED) and Emergency Medical Services (EMS) and may present with intoxication or long-term sequelae of alcohol misuse. Our study explored reasons for repeated ED/EMS utilisation and sought to understand perpetuating and protective factors for drinking. METHODS: Face-to-face semi-structured qualitative interviews were conducted. Participants were recruited from an ED in Singapore. Interviews were audio-recorded, transcribed verbatim and underwent manual thematic analysis. Emergent themes were independently reviewed for agreement. Data from medical records, interview transcripts, and field notes were triangulated for analysis. RESULTS: All participants were male (n = 20) with an average age of 55.6 years (SD = 8.86). Most were unemployed (75%), did not have tertiary education (75%), were divorced (55%), and had pre-existing psychiatric conditions (60%) and chronic cardiovascular conditions (75%). Reasons for utilisation included a perceived need due to symptoms, although sometimes it was bystanders who called the ambulance. ED/EMS was preferred due to the perceived higher quality and speed of care. Persistent drinking was attributed to social and environmental factors, and as a coping mechanism for stressors. Rehabilitation programs and meaningful activities reduced drinking tendencies. CONCLUSION: ED/EMS provide sought-after services for alcohol misuse patients, resulting in high utilisation. Social and medical intervention could improve drinking behaviours and decrease overall ED/EMS utilisation.

Validation of the CaRdiac Arrest Survival Score (CRASS) for predicting good neurological outcome after out-of-hospital cardiac arrest in an Asian emergency medical service system.

BACKGROUND: Survival with favorable neurological outcomes is an important indicator of successful resuscitation in out-of-hospital cardiac arrest (OHCA). We sought to validate the CaRdiac Arrest Survival Score (CRASS), derived using data from the German Resuscitation Registry, in predicting the likelihood of good neurological outcomes after OHCA in Singapore. METHODS: We conducted a retrospective population-based validation study among EMS-attended OHCA patients (≥18 years) in Singapore, using data from the prospective Pan-Asian Resuscitation Outcomes Study registry. Good neurological outcome was defined as a cerebral performance category of 1 or 2. To evaluate the CRASS score in light of the difference in patient characteristics, we used the default constant coefficient (0.8) and the adjusted coefficient (0.2) to calculate the probability of good neurological outcomes. RESULTS: Out of 11,404 analyzed patients recruited between April 2010 and December 2018, 260 had good and 11,144 had poor neurological function. The CRASS score demonstrated good discrimination, with an area under the curve of 0.963 (95% confidence interval: 0.952-0.974). Using the default constant coefficient of 0.8, the CRASS score consistently overestimated the predicted probability of a good outcome. Following adjustment of the coefficient to 0.2, the CRASS score showed improved calibration. CONCLUSION: CRASS demonstrated good discrimination and moderate calibration in predicting favorable neurological outcomes in the validation Singapore cohort. Our study established a good foundation for future large-scale, cross-country validations of the CRASS score in diverse sociocultural, geographical, and clinical settings.

A hypothetical implementation of 'Termination of Resuscitation' protocol for out-of-hospital cardiac arrest.

BACKGROUND: Out-of-hospital cardiac arrests with negligible chance of survival are routinely transported to hospital and many are pronounced dead thereafter. This leads to some potentially avoidable costs. The 'Termination of Resuscitation' protocol allows paramedics to terminate resuscitation efforts onsite for medically futile cases. This study estimates the changes in frequency of costly events that might occur when the protocol is applied to out-of-hospital cardiac arrests, as compared to existing practice. METHODS: We used Singapore data from the Pan-Asian Resuscitation Outcomes Study, from 1 Jan 2014 to 31 Dec 2017. A Markov model was developed to summarise the events that would occur in two scenarios, existing practice and the implementation of a Termination of Resuscitation protocol. The model was evaluated for 10,000 hypothetical patients with a cycle duration of 30 days after having a cardiac arrest. Probabilistic sensitivity analysis accounted for uncertainties in the outcomes: number of urgent transports and emergency treatments, inpatient bed days, and total number of deaths. RESULTS: For every 10,000 patients, existing practice resulted in 1118 (95% Uncertainty Interval 1117 to 1119) additional urgent transports to hospital and subsequent emergency treatments. There were 93 (95% Uncertainty Interval 66 to 120) extra inpatient bed days used, and 3 fewer deaths (95% Uncertainty Interval 2 to 4) in comparison to using the protocol. CONCLUSION: The findings provide some evidence for adopting the Termination of Resuscitation protocol. This policy could lead to a reduction in costs and non-beneficial hospital admissions, however there may be a small increase in the number of avoidable deaths.

Assessing unrealised potential for organ donation after out-of-hospital cardiac arrest.

BACKGROUND: Organ donation after brain death is the standard practice in many countries. Rates are low globally. This study explores the potential national number of candidates for uncontrolled donations after cardiac death (uDCD) amongst out-of-hospital cardiac arrest (OHCA) patients and the influence of extracorporeal cardiopulmonary resuscitation (ECPR) on the candidacy of these potential organ donors using Singapore as a case study. METHODS: Using Singapore data from the Pan-Asian Resuscitation Outcomes Study, we identified all non-traumatic OHCA cases from 2010 to 2016. Four established criteria for identifying uDCD candidates (Madrid, San Carlos Madrid, Maastricht and Paris) were retrospectively applied onto the population. Within these four groups, a condensed ECPR eligibility criteria was employed and thereafter, an estimated ECPR survival rate was applied, extrapolating for possible neurologically intact survivors had ECPR been administered. RESULTS: 12,546 OHCA cases (64.8% male, mean age 65.2 years old) qualified for analysis. The estimated number of OHCA patients who were eligible for uDCD ranged from 4.3 to 19.6%. The final projected percentage of potential uDCD donors readjusted for ECPR survivors was 4.2% (Paris criteria worst-case scenario, n = 532) to 19.4% of all OHCA cases (Maastricht criteria best-case scenario, n = 2428), for an estimated 14.3 to 65.4 uDCD donors per million population per year (pmp/year). CONCLUSIONS: In Singapore case study, we demonstrated the potential numbers of candidates for uDCD among resuscitated OHCA cases. This sizeable pool of potential donors demonstrates the potential for an uDCD program to expand the organ donor pool. A small proportion of these patients might however survive had they been administered ECPR. Further research into the factors influencing local organ and patient outcomes following uDCD and ECPR is indicated.

Is your unconscious patient in cardiac arrest? A New protocol for telephonic diagnosis by emergency medical call-takers: A national study.

BACKGROUND: Worldwide, call-taker recognition of out-of-hospital cardiac arrests (CA) suffers from poor accuracy, leading to missed opportunities for dispatcher-assisted cardiopulmonary resuscitation (DACPR) in CA patients and inappropriate DACPR in non-CA patients. Diagnostic protocols typically ask 2 questions in sequence: 'Is the patient conscious?' and 'Is the patient breathing normally?' As part of quality improvement efforts, our national emergency medical call centre changed the breathing question to an instruction for callers to place their hand onto the patient's abdomen to evaluate for the presence of breathing. METHODS: We performed a prospective before-and-after study of all unconscious cases from the national call centre database over a 31-day period in 2018. Cases were placed in 2 groups: 1) 'Before' group (standard protocol) where call-takers asked 'Is the patient breathing normally?' and 2) 'After' group (modified protocol) where callers were instructed to place their hand on the patient's abdomen. In an intention-to-treat analysis, the accuracy, sensitivity and specificity of both protocols for determining CA were compared. RESULTS: 1557 calls presented with unconsciousness, of which 513 cases were included. 231 cases were in the 'Before' group and 282 cases were in the 'After' group. The 'After' showed superior accuracy (84.4% vs 67.5%), sensitivity (75.0% vs 40.4%) and specificity (87.9% vs 75.4%) when compared to the standard protocol. Adherence in the 'Before' group to the standard protocol was 100%. However, adherence in the 'After' group to the modified protocol was 50.4%. Per protocol analysis comparing the modified protocol with the standard protocol showed vastly improved accuracy (96.5% vs 69.3%), sensitivity (94.1% vs 39.0%) and specificity (97.8% vs 77.2%) of the modified protocol. In patients with true cardiac arrest, the median time to 1st compression was 32.5 s longer in the modified protocol group when compared to the standard protocol group, approaching significance (199.5 s vs 167.0 s, p = 0.059). Median time to recognize CA was similar in both groups. CONCLUSION: Dispatch assessment using the hand on abdomen method appeared feasible but uptake by dispatch staff was moderate. Diagnostic performance of this method should be verified in randomised trials.

Nationwide trends in residential and non-residential out-of-hospital cardiac arrest and differences in bystander cardiopulmonary resuscitation.

AIMS: Singapore is highly-urbanized, with >90% of the population living in high-rise apartments. She has implemented several city-wide interventions such as dispatcher-assisted CPR, community CPR training and smartphone activation of volunteers to increase bystander CPR (BCPR) rates for out-of-hospital cardiac arrest (OHCA). These may have different impact on residential and non-residential OHCA. We aimed to evaluate the characteristics, processes-of-care and outcome differences between residential and non-residential OHCA and study the differences in temporal trends of BCPR rates. METHODS: This was a national, observational study in Singapore from 2010 to 2016, using data from the prospective Pan-Asian Resuscitation Outcomes Study. The primary outcome was survival (to-discharge or to-30-days). Multivariate logistic regression was performed to determine the effect of location-type on survival and a test of statistical interaction was performed to assess the difference in the temporal relationship of BCPR rates between location-type. RESULTS: 8397 cases qualified for analysis, of which 5990 (71.3%) were residential. BCPR and bystander automated external defibrillator (AED) rates were significantly lower in residential as compared to non-residential arrests (41.0% vs 53.6%, p < 0.01; 0.4% vs 10.8%, p < 0.01 respectively). Residential BCPR increased from 15.8% (2010) to 57.1% (2016). Residential cardiac arrests had lower survival-to-discharge (2.9% vs 10.1%, p < 0.01). Multivariate logistic regression analysis showed that location-type had an independent effect on survival, with residential arrests having poorer survival compared to non-residential cardiac arrests (adjusted OR 0.547 [0.435-0.688]). A test of statistical interaction showed a significant interaction effect between year and location-type for bystander CPR, with a narrowing of differences in bystander CPR between residential and non-residential cardiac arrests over the years. CONCLUSION: Residential cardiac arrests had poorer bystander intervention and survival from 2010 to 2016 in Singapore. BCPR had improved more in residential arrests compared to non-residential arrests over a period of city-wide interventions to improve BCPR.

Effectiveness of a community based out-of-hospital cardiac arrest (OHCA) interventional bundle: Results of a pilot study.

BACKGROUND: 70% of Out-of-hospital cardiac arrests (OHCA) in Singapore occur in residential areas, and are associated with poorer outcomes. We hypothesized that an interventional bundle consisting of Save-A-life (SAL) initiative (cardiopulmonary resuscitation (CPR)/automated external defibrillator (AED) training and public-housing AED installation), dispatcher-assisted CPR (DA-CPR) program and myResponder (mobile application) will improve OHCA survival. METHODS: This is pilot data from initial implementation of a stepped-wedge, before-after, real-world interventional bundle in six selected regions. Under the SAL initiative, 30,000 individuals were CPR/AED trained, with 360 AEDs installed. Data was obtained from Singapore's national OHCA Registry. We included all adult patients who experienced OHCA in Singapore from 2011 to 2016 within study regions, excluding EMS-witnessed cases and cases due to trauma/drowning/ electrocution. Cases occurring before and after intervention were allocated as control and intervention groups respectively. Survival was assessed via multivariable logistic regression. RESULTS: 1241 patients were included for analysis (Intervention: 361; Control: 880). The intervention group had higher mean age (70 vs 67 years), survival (3.3% [12/361] vs. 2.2% [19/880]), pre-hospital return of spontaneous circulation (ROSC) (9.1% [33/361] vs 5.1% [45/880]), bystander CPR (63.7% [230/361] vs 44.8% [394/880]) and bystander AED application (2.8% [10/361] vs 1.1% [10/880]). After adjusting for age, gender, race and significant covariates, the intervention was associated with increased odds ratio (OR) for survival (OR 2.39 [1.02-5.62]), pre-hospital ROSC (OR 1.94 [1.15-3.25]) and bystander CPR (OR 2.29 [1.77-2.96]). CONCLUSION: The OHCA interventional bundle (SAL initiative, DA-CPR, myResponder) significantly improved survival and is being scaled up as a national program.

Impact of bystander-focused public health interventions on cardiopulmonary resuscitation and survival: a cohort study.

BACKGROUND: Bystander cardiopulmonary resuscitation (CPR) increases an individual's chance of survival from out-of-hospital cardiac arrest (OHCA), but the frequency of bystander CPR is low in many communities. We aimed to assess the cumulative effect of CPR-targeted public health interventions in Singapore, which were incrementally introduced between 2012 and 2016. METHODS: We did a secondary analysis of a prospective cohort study of adult, non-traumatic OHCAs, through the Singapore registry. National interventions introduced during this time included emergency services interventions, as well as dispatch-assisted CPR (introduced on July 1, 2012), a training programme for CPR and automated external defibrillators (April 1, 2014), and a first responder mobile application (myResponder; April 17, 2015). Using multilevel mixed-effects logistic regression, we modelled the likelihood of receiving bystander CPR with the increasing number of interventions, accounting for year as a random effect. FINDINGS: The Singapore registry contained 11 465 OHCA events between Jan 1, 2011, and Dec 31, 2016. Paediatric arrests, arrests witnessed by emergency medical services, and healthcare-facility arrests were excluded, and 6788 events were analysed. Bystander CPR was administered in 3248 (48%) of 6788 events. Compared with no intervention, likelihood of bystander CPR was not significantly altered by the addition of emergency medical services interventions (odds ratio [OR] 1·33 [95% CI 0·98-1·79]; p=0·065), but increased with implementation of dispatch-assisted CPR (3·72 [2·84-4·88]; p<0·0001), with addition of the CPR and automated external defibrillator training programme (6·16 [4·66-8·14]; p<0·0001), and with addition of the myResponder application (7·66 [5·85-10·03]; p<0·0001). Survival to hospital discharge increased after the addition of all interventions, compared with no intervention (OR 3·10 [95% CI 1·53-6·26]; p<0·0001). INTERPRETATION: National bystander-focused public health interventions were associated with an increased likelihood of bystander CPR, and an increased survival to hospital discharge. Understanding the combined impact of public health interventions might improve strategies to increase the likelihood of bystander CPR, and inform targeted initiatives to improve survival from OHCA. FUNDING: National Medical Research Council, Clinician Scientist Award, Singapore and Ministry of Health, Health Services Research Grant, Singapore.

Implementation of a National 5-Year Plan for Prehospital Emergency Care in Singapore and Impact on Out-of-Hospital Cardiac Arrest Outcomes From 2011 to 2016.

Background Outcomes of patients from out-of-hospital cardiac arrest (OHCA) vary widely globally because of differences in prehospital systems of emergency care. National efforts had gone into improving OHCA outcomes in Singapore in recent years including community and prehospital initiatives. We aimed to document the impact of implementation of a national 5-year Plan for prehospital emergency care in Singapore on OHCA outcomes from 2011 to 2016. Methods and Results Prospective, population-based data of OHCA brought to Emergency Departments were obtained from the Pan-Asian Resuscitation Outcomes Study cohort. The primary outcome was Utstein (bystander witnessed, shockable rhythm) survival-to-discharge or 30-day postarrest. Mid-year population estimates were used to calculate age-standardized incidence. Multivariable logistic regression was performed to identify prehospital characteristics associated with survival-to-discharge across time. A total of 11 465 cases qualified for analysis. Age-standardized incidence increased from 26.1 per 100 000 in 2011 to 39.2 per 100 000 in 2016. From 2011 to 2016, Utstein survival rates nearly doubled from 11.6% to 23.1% (P=0.006). Overall survival rates improved from 3.6% to 6.5% (P<0.001). Bystander cardiopulmonary resuscitation rates more than doubled from 21.9% to 56.3% and bystander automated external defibrillation rates also increased from 1.8% to 4.6%. Age ≤65 years, nonresidential location, witnessed arrest, shockable rhythm, bystander automated external defibrillation, and year 2016 were independently associated with improved survival. Conclusions Implementation of a national prehospital strategy doubled OHCA survival in Singapore from 2011 to 2016, along with corresponding increases in bystander cardiopulmonary resuscitation and bystander automated external defibrillation. This can be an implementation model for other systems trying to improve OHCA outcomes.

Effect of vertical location on survival outcomes for out-of-hospital cardiac arrest in Singapore.

BACKGROUND: A large proportion of out-of-hospital cardiac arrest (OHCA) cases occur in high-rise residential buildings. This study aims to investigate the effect of vertical location on survival outcomes and response times. METHODS: This is a retrospective study based on data obtained from the Singapore cohort of the Pan-Asian Resuscitation Outcomes Study (PAROS) from January 2011 to December 2014. Study subjects were OHCA cases, unwitnessed and transported by EMS personnel, with known vertical location (floor) data. Traumatic arrests with no resuscitation attempted and missing vertical locations were excluded. The primary outcome was survival to hospital discharge or 30 days post-cardiac arrest. RESULTS: A total of 5678 OHCA cases were included in the study. The effect of floors on survival was manifested as a U-shaped response. Survival rates of 4.5% for the 4 pooled basement floors and 6.2% for the ground floor (floor 1) were contrasted by a substantial drop to 2.7% at floor 2 and continuing decline to 0.7% at floor 6. In a multivariable model using stepwise logistic regression, both linear (p = 0.0285) and quadratic (p = 0.0018) floor effects remained significant after adjustment for other significant risk factors, age, bystander witnessed arrest, first arrest rhythm, ROSC on scene/enroute, and EMS response times. Harrell's C-statistic for a predictive model incorporating these variables was 0.933. CONCLUSIONS: Vertical location is associated with OHCA survival probability with a U-shaped response, and this significance remained after adjustment for other significant OHCA variables. This relationship is likely multifactorial and more research is needed to elucidate the various factors.