Occult Overdose Masquerading as Sudden Cardiac Death: From the POstmortem Systematic InvesTigation of Sudden Cardiac Death Study

Trends in presumed drug overdose out-of-hospital cardiac arrests in San Francisco, 2015-2023

INTRODUCTION

Estimates of the prevalence of drug-related out of hospital cardiac arrest (OHCA) vary, ranging from 1.8% to 10.0% of medical OHCA. However, studies conducted prior to the recent wave of fentanyl deaths likely underestimate the current prevalence of drug-related OHCA. We evaluated recent trends in drug-related OHCA, hypothesizing that the proportion of presumed drug-related OHCA treated by emergency medical services (EMS) has increased since 2015.

METHODS

We conducted a retrospective analysis of OHCA patients treated by EMS providers in San Francisco, California between 2015 and 2023. Participants included OHCA cases in which resuscitation was attempted by EMS. The study exposure was the year of arrest. Our primary outcome was the occurrence of drug-related OHCA, defined as the EMS impression of OHCA caused by a presumed or known overdose of medication(s) or drug(s).

RESULTS

From 2015 to 2023, 5044 OHCA resuscitations attended by EMS (average 561 per year) met inclusion criteria. The median age was 65 (IQR 50-79); 3508 (69.6%) were male. The EMS impression of arrest etiology was drug-related in 446/5044 (8.8%) of OHCA. The prevalence of presumed drug-related OHCA increased significantly each year from 1% in 2015 to 17.6% in 2023 (p-value for trend = 0.0001). After adjustment, presumed drug-related OHCA increased by 30% each year from 2015-2023.

CONCLUSION

Drug-related OHCA is an increasingly common etiology of OHCA. In 2023, one in six OHCA was presumed to be drug related. Among participants less than 60 years old, one in three OHCA was presumed to be drug related.

Implementation of Opioid Safety Efforts: Influence of Academic Detailing on Adverse Outcomes Among Patients in the Veterans Health Administration

BACKGROUND

The Veterans Health Administration (VA) implemented academic detailing (AD) to support safer opioid prescribing and overdose prevention initiatives.

METHODS

Patient-level data were extracted monthly from VA's electronic health record to evaluate whether AD implementation was associated with changes in all-cause mortality, opioid poisoning inpatient admissions, and opioid poisoning emergency department (ED) visits in an observational cohort of patients with long-term opioid prescriptions (≥45-day supply of opioids 6 months prior to a given month with ≤15 days between prescriptions). A single-group interrupted time series analysis using segmented logistic regression for mortality and Poisson regression for counts of inpatient admissions and ED visits was used to identify whether the level and slope of these outcomes changed in response to AD implementation.

RESULTS

Among 955 376 unique patients (19 431 241 person-months), there were 53 369 deaths (29 025 pre-AD; 24 344 post-AD), 1927 opioid poisoning inpatient admissions (610 pre-AD; 1317 post-AD), and 408 opioid poisoning ED visits (207 pre-AD; 201 post-AD). Immediately after AD implementation, there was a 5.8% reduction in the odds of all-cause mortality (95% confidence interval [CI]: 0.897, 0.990). However, patients had a significantly increased incidence rate of inpatient admissions for opioid poisoning immediately after AD implementation (incidence rate ratio = 1.523; 95% CI: 1.118, 2.077). No significant differences in ED visits for opioid poisoning were observed.

CONCLUSIONS

AD was associated with decreased all-cause mortality but increased inpatient hospitalization for opioid poisoning among patients prescribed long-term opioids. Mechanisms via which AD's efforts influenced opioid-related outcomes should be explored.

Homelessness and Incidence and Causes of Sudden Death: Data From the POST SCD Study

Importance

Over 580 000 people in the US experience homelessness, with one of the largest concentrations residing in San Francisco, California. Unhoused individuals have a life expectancy of approximately 50 years, yet how sudden death contributes to this early mortality is unknown.

Objective

To compare incidence and causes of sudden death by autopsy among housed and unhoused individuals in San Francisco County.

Design, Setting, and Participants

This cohort study used data from the Postmortem Systematic Investigation of Sudden Cardiac Death (POST SCD) study, a prospective cohort of consecutive out-of-hospital cardiac arrest deaths countywide among individuals aged 18 to 90 years. Cases meeting World Health Organization criteria for presumed SCD underwent autopsy, toxicologic analysis, and medical record review. For rate calculations, all 525 incident SCDs in the initial cohort were used (February 1, 2011, to March 1, 2014). For analysis of causes, 343 SCDs (incident cases approximately every third day) were added from the extended cohort (March 1, 2014, to December 16, 2018). Data analysis was performed from July 1, 2022, to July 1, 2023.

Main Outcomes and Measures

The main outcomes were incidence and causes of presumed SCD by housing status. Causes of sudden death were adjudicated as arrhythmic (potentially rescuable with implantable cardioverter-defibrillator), cardiac nonarrhythmic (eg, tamponade), or noncardiac (eg, overdose).

Results

A total of 868 presumed SCDs over 8 years were identified: 151 unhoused individuals (17.4%) and 717 housed individuals (82.6%). Unhoused individuals compared with housed individuals were younger (mean [SD] age, 56.7 [0.8] vs 61.0 [0.5] years, respectively) and more often male (132 [87.4%] vs 499 [69.6%]), with statistically significant racial differences. Paramedic response times were similar (mean [SD] time to arrival, unhoused individuals: 5.6 [0.4] minutes; housed individuals: 5.6 [0.2] minutes; P = .99), while proportion of witnessed sudden deaths was lower among unhoused individuals compared with housed individuals (27 [18.0%] vs 184 [25.7%], respectively, P = .04). Unhoused individuals had higher rates of sudden death (incidence rate ratio [IRR], 16.2; 95% CI, 5.1-51.2; P < .001) and arrhythmic death (IRR, 7.2; 95% CI, 1.3-40.1; P = .02). These associations remained statistically significant after adjustment for differences in age and sex. Noncardiac causes (96 [63.6%] vs 270 [37.7%], P < .001), including occult overdose (48 [31.8%] vs 90 [12.6%], P < .001), gastrointestinal causes (8 [5.3%] vs 15 [2.1%], P = .03), and infection (11 [7.3%] vs 20 [2.8%], P = .01), were more common among sudden deaths in unhoused individuals. A lower proportion of sudden deaths in unhoused individuals were due to arrhythmic causes (48 of 151 [31.8%] vs 420 of 717 [58.6%], P < .001), including acute and chronic coronary disease.

Conclusions and Relevance

In this cohort study among individuals who experienced sudden death in San Francisco County, homelessness was associated with greater risk of sudden death from both noncardiac causes and arrhythmic causes potentially preventable with a defibrillator.

Multiple substance use and blood pressure in women experiencing homelessness

Background

Substance use increases risk of cardiovascular events, particularly among women with additional risk factors like housing instability. While multiple substance use is common among unstably housed individuals, relationships between multiple substance use and cardiovascular risk factors like blood pressure are not well characterized.

Methods

We conducted a cohort study between 2016 and 2019 to examine associations between multiple substance use and blood pressure in women experiencing homelessness and unstable housing. Participants completed six monthly visits including vital sign assessment, interview, and blood draw to assess toxicology-confirmed substance use (e.g., cocaine, alcohol, opioids) and cardiovascular health. We used linear mixed models to evaluate the outcomes of systolic and diastolic blood pressure (SBP; DBP).

Results

Mean age was 51.6 years; 74 % were women of color. Prevalence of any substance use was 85 %; 63 % of participants used at least two substances at baseline. Adjusting for race, body mass index and cholesterol, cocaine was the only substance significantly associated with SBP (4.71 mmHg higher; 95 % CI 1.68, 7.74) and DBP (2.83 mmHg higher; 95 % CI 0.72, 4.94). Further analysis found no differences in SBP or DBP between those with concurrent use of other stimulants, depressants, or both with cocaine, compared to those who used cocaine only.

Conclusions

Cocaine was the only substance associated with higher SBP and DBP, even after accounting for simultaneous use of other substances. Along with interventions to address cocaine use, stimulant use screening during cardiovascular risk assessment and intensive blood pressure management may improve cardiovascular outcomes among women experiencing housing instability.

Opioid-related Mortality in United States Death Certificate Data: A Quantitative Bias Analysis With Expert Elicitation of Bias Parameters

BACKGROUND

Opioid-related mortality is an important public health problem in the United States. Incidence estimates rely on death certificate data generated by health care providers and medical examiners. Opioid overdoses may be underreported when other causes of death appear plausible. We applied physician-elicited death certificate bias parameters to quantitative bias analyses assessing potential age-related differential misclassification in US opioid-related mortality estimates.

METHODS

We obtained cause-of-death data (US, 2017) from the National Center for Health Statistics and calculated crude opioid-related outpatient death counts by age category (25-54, 55-64, 65+). We elicited beliefs from 10 primary care physicians on sensitivity of opioid-related death classification from death certificates. We summarized elicited sensitivity estimates, calculated plausible specificity values, and applied resulting parameters in a probabilistic bias analysis.

RESULTS

Physicians estimated wide sensitivity ranges for classification of opioid-related mortality by death certificates, with lower estimated sensitivities among older age groups. Probabilistic bias analyses adjusting for physician-estimated misclassification indicated 3.1 times more (95% uncertainty interval: 1.2-23.5) opioid-related deaths than the observed death count in the 65+ age group. All age groups had substantial increases in bias-adjusted death counts.

CONCLUSIONS

We developed and implemented a feasible method of eliciting physician expert opinion on bias parameters for sensitivity of a medical record-based death indicator and applied findings in quantitative bias analyses adjusting for differential misclassification. Our findings are consistent with the hypothesis that opioid-related mortality rates may be substantially underestimated, particularly among older adults, due to misclassification in cause-of-death data from death certificates.

Implementation of a Leave-behind Naloxone Program in San Francisco: A One-year Experience

Introduction: In response to the ongoing opioid overdose crisis, US officials urged the expansion of access to naloxone for opioid overdose reversal. Since then, emergency medical services’ (EMS) dispensing of naloxone kits has become an emerging harm reduction strategy. Methods: We created a naloxone training and low-barrier distribution program in San Francisco: Project FRIEND (First Responder Increased Education and Naloxone Distribution). The team assembled an advisory committee of stakeholders and subject-matter experts, worked with local and state EMS agencies to augment existing protocols, created training curricula, and developed a naloxone-distribution data collection system. Naloxone kits were labeled for registration and data tracking. Emergency medical technicians and paramedics were asked to distribute naloxone kits to any individuals (patient or bystander) they deemed at risk of experiencing or witnessing an opioid overdose, and to voluntarily register those kits. Results: Training modalities included a video module (distributed to over 700 EMS personnel) and voluntary, in-person training sessions, attended by 224 EMS personnel. From September 25, 2019–September 24, 2020, 1,200 naloxone kits were distributed to EMS companies. Of these, 232 kits (19%) were registered by EMS personnel. Among registered kits, 146 (63%) were distributed during encounters for suspected overdose, and 103 (44%) were distributed to patients themselves. Most patients were male (n = 153, 66%) and of White race (n = 124, 53%); median age was 37.5 years (interquartile range 31-47). Conclusion: We describe a successful implementation and highlight the feasibility of a low-threshold, leave-behind naloxone program. Collaboration with multiple entities was a key component of the program’s success.

Antemortem and Post-Mortem Characteristics of Lethal Mitral Valve Prolapse Among All Countywide Sudden Deaths

OBJECTIVES

The goal of this study was to investigate the characteristics of mitral valve prolapse (MVP) in a post-mortem study of consecutive sudden cardiac deaths (SCDs) in subjects up to 90 years of age.

BACKGROUND

Up to 2.3% of subjects with MVPs experience SCD, but by convention SCD is rarely confirmed by autopsy. In a post-mortem study of persons <40 years of age, 7% of SCDs were caused by MVP; bileaflet involvement, mitral annular disjunction (MAD), and replacement fibrosis were common.

METHODS

In the San Francisco POST SCD (Postmortem Systematic Investigation of Sudden Cardiac Death) study, autopsies have been performed on >1,000 consecutive World Health Organization-defined (presumed) cases of SCD in subjects aged 18 to 90 years since 2011; a total of 603 were adjudicated. Autopsy-defined sudden arrhythmic death (SAD) required absence of nonarrhythmic cause; MVP diagnosis required leaflet billowing. One hundred antemortem echocardiograms were revised to identify additional MVPs missed on autopsy.

RESULTS

Among the 603 presumed SCDs, 339 (56%) were autopsy-defined SADs, with MVP identified in 7 (1%). Six additional MVPs were identified by review of echocardiograms, for a prevalence of at least 2% among 603 presumed SCDs and 4% among 339 SADs (vs. 264 non-SADs; p = 0.02). All 6 additional MVPs had monoleaflet rather than bileaflet involvement and mild mitral regurgitation, ruling out hemodynamic cause. Less than one-half had MAD with replacement fibrosis, but all had multisite interstitial fibrosis.

CONCLUSIONS

In a countywide post-mortem study of all adult cases of SCD, MVP prevalence was at least 4% of SADs, but one-half were missed on autopsy. Monoleaflet MVP was often underdiagnosed post-mortem. Compared with young cases of SCD, lethal MVP in older cases of SCD did not consistently have bileaflet anatomy, replacement fibrosis, or MAD.

NAloxone CARdiac Arrest Decision Instruments (NACARDI) for targeted antidotal therapy in occult opioid overdose precipitated cardiac arrest

BACKGROUND

We have recently demonstrated that a significant proportion of fatal out-of-hospital cardiac arrests (OHCAs) are precipitated by occult overdose, which could benefit from antidote therapy administered adjunctively with other cardiac resuscitation measures. We sought to develop simple decision instruments that EMS providers and other first responders can use to rapidly identify occult opioid overdose-associated OHCAs.

METHODS

We examined data from February 2011 through December 2017 in the Postmortem Systematic Investigation of Sudden Cardiac Death study, in which San Francisco (California) County EMS-attended OHCA deaths received autopsy and expert panel adjudication of cause of death. Using classification tree analyses, we derived highly sensitive and specific decision instruments that predicted our primary outcome of occult opioid OD-associated OHCA. We then calculated screening performance characteristics of these instruments.

RESULTS

Of 767 OHCA deaths, 80 (10.4%) were associated with occult opioid overdose. Of the eight models with 100% sensitivity for opioid overdose-associated cardiac arrest, the highest specificity model (23.4%, 95% confidence interval [CI] 20.3-26.7%) was age < 60 years OR race = black or non-Latinx white OR arrest in public place. The highest specificity instrument (96.3%, 95% CI 94.6-97.5%) consisting of age < 60 years AND race = black or non-Latinx white AND unwitnessed arrest AND female sex had 25% (95% CI 16-35.9%) sensitivity.

CONCLUSIONS

We have derived simple decision instruments that can identify patients whose OHCA precipitant was occult opioid overdose. These instruments may be used to guide selective administration of the antidote naloxone in OHCA resuscitations.