Sudden Unexpected Death in North Carolina (SUDDEN): methodology review and screening results

Fine particulate matter-sudden death association modified by ventricular hypertrophy and inflammation: a case-crossover study

Background

Sudden death accounts for approximately 10% of deaths among working-age adults and is associated with poor air quality. Objectives: To identify high-risk groups and potential modifiers and mediators of risk, we explored previously established associations between fine particulate matter (PM2.5) and sudden death stratified by potential risk factors.

Methods

Sudden death victims in Wake County, NC, from 1 March 2013 to 28 February 2015 were identified by screening Emergency Medical Systems reports and adjudicated (n = 399). Daily PM2.5 concentrations for Wake County from the Air Quality Data Mart were linked to event and control periods. Potential modifiers included greenspace metrics, clinical conditions, left ventricular hypertrophy (LVH), and neutrophil-to-lymphocyte ratio (NLR). Using a case-crossover design, conditional logistic regression estimated the OR (95%CI) for sudden death for a 5 μg/m3 increase in PM2.5 with a 1-day lag, adjusted for temperature and humidity, across risk factor strata.

Results

Individuals having LVH or an NLR above 2.5 had PM2.5 associations of greater magnitude than those without [with LVH OR: 1.90 (1.04, 3.50); NLR > 2.5: 1.25 (0.89, 1.76)]. PM2.5 was generally less impactful for individuals living in areas with higher levels of greenspace.

Conclusion

LVH and inflammation may be the final step in the causal pathway whereby poor air quality and traditional risk factors trigger arrhythmia or myocardial ischemia and sudden death. The combination of statistical evidence with clinical knowledge can inform medical providers of underlying risks for their patients generally, while our findings here may help guide interventions to mitigate the incidence of sudden death.

Advancing Cardiovascular Risk Assessment with Artificial Intelligence: Opportunities and Implications in North Carolina

Cardiovascular disease mortality is increasing in North Carolina with persistent inequality by race, income, and location. Artificial intelligence (AI) can repurpose the widely available electrocardiogram (ECG) for enhanced assessment of cardiac dysfunction. By identifying accelerated cardiac aging from the ECG, AI offers novel insights into risk assessment and prevention.

Characteristics of sudden death by clinical criteria

Sudden death is a leading cause of deaths nationally. Definitions of sudden death vary greatly, resulting in imprecise estimates of its frequency and incomplete knowledge of its risk factors. The degree to which time-based and coronary artery disease (CAD) criteria impacts estimates of sudden death frequency and risk factors is unknown. Here, we apply these criteria to a registry of all-cause sudden death to assess its impact on sudden death frequency and risk factors. The sudden unexpected death in North Carolina (SUDDEN) project is a registry of out of-hospital, adjudicated, sudden unexpected deaths attended by Emergency Medical Services. Deaths were not excluded by time since last seen or alive or by prior symptoms or diagnosis of CAD. Common criteria for sudden death based on time since last seen alive (both 24 hours and 1 hour) and prior diagnosis of CAD were applied to the SUDDEN case registry. The proportion of cases satisfying each of the 4 criteria was calculated. Characteristics of victims within each restrictive set of criteria were measured and compared to the SUDDEN registry. There were 296 qualifying sudden deaths. Application of 24 hour and 1 hour timing criteria compared to no timing criteria reduced cases by 25.0% and 69.6%, respectively. Addition of CAD criteria to each timing criterion further reduced qualifying cases, for a total reduction of 81.8% and 90.5%, respectively. However, characteristics among victims meeting restrictive criteria remained similar to the unrestricted population. Timing and CAD criteria dramatically reduces estimates of the number of sudden deaths without significantly impacting victim characteristics.

Design of a Novel Intervention Model to Address Cardiovascular Health Disparities in the Rural Underserved Community of Phillips County Arkansas

Devastating health-related disparities driven by an entanglement of factors disproportionately impact the underserved, low-wealth, and minority community of Phillips county (PC) in the Arkansas Delta Region (ADR). Cardiovascular disease continues to increase with widespread consequences on the local economy, health care systems, and population. Health care and community-based systems have been unsuccessful in reducing out-of-hospital cardiac death, particularly in the ADR, for many reasons. Herein, we share the strategy behind, planning, and goals of The Arkansas Lincoln Project, a novel neighborhood-based strategy bridging the gap between residents, social resources, and health care services in PC.

Mental Disorders, Substance Use Disorders, and Psychotropic Medication Use Among Sudden-Death Victims

OBJECTIVE

The authors sought to estimate the prevalence of mental and substance use disorders and psychotropic medication prescriptions among working-age sudden-death victims.

METHODS

Using a written protocol, the authors screened for sudden deaths attended by emergency medical services (EMS) in a large metropolitan county in North Carolina from March 1, 2013, to February 28, 2015. Sudden-death cases were adjudicated by three cardiologists. Mental health and chronic disease diagnoses and treatments were abstracted from EMS, medical examiner, toxicology, and autopsy reports and from clinical records for the past 5 years before death.

RESULTS

Sudden death was identified for 399 adults ages 18-64 years, 270 of whom had available medical records. Most sudden-death victims were White (63%) and male (65%), had a comorbid condition such as hypertension or respiratory disease, and had a mean±SD age of death of 53.6±8.8 years. Most victims (59%) had at least one mental health or substance use disorder documented in a recent medical record; 76%-78% of victims with a mental disorder had a documented psychotropic medication prescription. However, fewer than one-half (41%) had a documented referral to a mental health professional. The most common diagnostic categories were depressive, anxiety, and alcohol-related disorders. Almost one-half (46%) of the victims had a recent psychotropic prescription, most commonly antidepressants (29%) and benzodiazepines (19%).

CONCLUSIONS

Mental illness, substance use disorders, and psychotropic medication prescriptions were prevalent among sudden-death victims. The health care needs of these individuals may be better addressed by collaborative care for general medical and mental disorders.

High Prevalence of Diabetes Mellitus and Mental Illness Among Victims of Sudden Death

OBJECTIVES

Diabetes mellitus (DM) increases the risk of cardiovascular disease and is associated with sudden death. Mental illness among individuals with DM may confound medical care. This study assessed the association of mental illness with DM and poorly controlled DM in sudden death victims.

METHODS

We screened out-of-hospital deaths ages 18 to 64 years in Wake County, North Carolina from 2013 to 2015 to adjudicate sudden deaths. We abstracted demographics and clinical characteristics from health records. Mental illness included anxiety, schizophrenia, bipolar disorder, or depression. Poorly controlled DM was defined as a hemoglobin A1c >8 or taking ≥3 medications for glycemic control. Logistic regression assessed the association between DM and mental illness.

RESULTS

Among victims with available records, 109 (29.4%) had DM. Of those, 62 (56.9%) had mental illness. Mental illness was present in 53.42% and 63.89% of victims with mild and poorly controlled DM, respectively. Mental illness was associated with DM (adjusted odds ratio 2.46, 95% confidence interval 1.57-3.91). Victims with poorly controlled DM were more likely to have mental illness (adjusted odds ratio 2.66, 95% confidence interval 1.14-6.18).

CONCLUSIONS

DM is a common comorbid condition in sudden death victims. Among victims, mental illness is associated with the control of DM. Early management of comorbid mental illnesses may improve the care of patients with DM and reduce the incidence of sudden death.

Stall in Heart Disease Death Rates, Evidence From Maine, 1999-2017

INTRODUCTION

Since the 1950s, heart disease deaths have declined in the United States, but recent reports indicate a plateau in this decline. Heart disease death rates increased in Maine from 2011-2015. We examined reasons for the trend change in Maine's heart disease death rates, including the contributing types of heart disease.

METHODS

We obtained Maine's annual heart disease death data for 1999-2017 from CDC's Wide-ranging Online Data for Epidemiologic Research (CDC WONDER). We used joinpoint regression to determine changes in trend and annual percentage change (APC) in death rates for heart disease overall and by demographic groups, types of heart disease, and geographic area.

RESULTS

Joinpoint modeling showed that Maine's age-adjusted heart disease death rates decreased during 1999-2010 (-4.2% APC), then plateaued during 2010-2017 (-0.1% APC). Death rates flattened for both sexes and age groups ≥45 years. Although death rates for acute myocardial infarction (AMI) decreased through 2017, hypertensive heart disease (HHD) and heart failure death rates increased. Death rates attributable to diabetes-related heart disease and non-AMI ischemic heart disease (IHD) plateaued.

CONCLUSION

Declines in Maine's heart disease death rates have plateaued, similar to national trends. Flattening rates appear to be driven by adverse trends in HHD, heart failure, diabetes-related heart disease, and non-AMI IHD. Increased efforts to address cardiovascular disease risk factors, chronic heart disease, and access to care are necessary to continue the decrease in heart disease deaths in Maine.

Cardiac arrest and sudden cardiac death registries: a systematic review of global coverage

Background

Sudden cardiac death (SCD) is a major global health problem, accounting for up to 20% of deaths in Western societies. Clinical quality registries have been shown in a range of disease conditions to improve clinical management, reduce variation in care and improve outcomes.

Aim

To identify existing cardiac arrest (CA) and SCD registries, characterising global coverage and methods of data capture and validation.

Methods

Biomedical and public search engines were searched with the terms ‘registry cardio*’; ‘sudden cardiac death registry’ and ‘cardiac arrest registry’. Registries were categorised as either CA, SCD registries or ‘other’ according to prespecified criteria. SCD registry coordinators were contacted for contemporaneous data regarding registry details.

Results

Our search strategy identified 49 CA registries, 15 SCD registries and 9 other registries (ie, epistries). Population coverage of contemporary CA and SCD registries is highly variable with registries densely concentrated in North America and Western Europe. Existing SCD registries (n=15) cover a variety of age ranges and subpopulations, with some enrolling surviving patients (n=8) and family members (n=5). Genetic data are collected by nine registries, with the majority of these (n=7) offering indefinite storage in a biorepository.

Conclusions

Many CA registries exist globally, although with inequitable population coverage. Comprehensive multisource surveillance SCD registries are fewer in number and more challenging to design and maintain. Challenges identified include maximising case identification and case verification.

Trial registration number

CRD42019118910.

A case-crossover analysis of the relationship of air pollution with out-of-hospital sudden unexpected death in Wake County, North Carolina (2013-2015)

Out-of-hospital sudden unexpected deaths are non-accidental deaths that occur without obvious underlying causes and may account for 10% of natural deaths before age 65. Short-term exposure to ambient air pollution is associated with all-cause (non-accidental) and cause-specific (e.g., cardiovascular) mortality, and with immediate exposures often yielding the highest magnitude risk estimates. Few studies have focused on short-term exposure to air pollution and sudden unexpected deaths. Using the University of North Carolina Sudden Unexpected Death in North Carolina population, we examine associations between short-term criteria air pollutant exposures with sudden unexpected deaths using a time-stratified case-crossover design, with data on criteria air pollutants from the Environmental Protection Agency's Air Quality System. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression with air pollutant exposures scaled to roughly inter-quartile ranges; models were adjusted for average temperature and relative humidity on event day and preceding 3 days. Potential for confounding by co-pollutants were examined in two pollutant models. ORs for PM_2.5 at lag day 1 were elevated (adjusted OR for 5 μg/m³ increase: 1.17 (0.98, 1.40)), and were robust to co-pollutant adjustment. Elevated odds were observed for SO₂ at lag day 0, and reduced odds for O₃ at lag day 0; however, these associations were somewhat attenuated toward the null (SO₂) or were not robust (O₃) to co-pollutant adjustment. This analysis in a racially and socioeconomically diverse cohort, with a more inclusive definition of sudden unexpected death than is typically employed offers evidence that PM_2.5 may be a clinically relevant trigger of sudden unexpected deaths in susceptible individuals.

Years of Life and Productivity Loss Because of Adult Sudden Unexpected Death in the United States

BACKGROUND

Few studies have evaluated the years of life lost (YLL) and productivity loss due to sudden unexpected death (SUD). The burden of SUD on society is undetermined because of lack of population-based studies and comprehensive adjudication methods.

OBJECTIVE

We estimated YLL and productivity loss from SUD in working-age adults and compared it with the leading causes of death in the United States.

METHODS

We screened all out of hospital deaths among people aged 20-64 in Wake County, NC from 2013 to 2015 to adjudicate SUDs. We extrapolated Wake County incidence to estimate the age-standardized and sex-standardized rate of SUD in the United States. YLL was calculated based on the remaining life expectancy of the victims. Incorporating market and housekeeping value estimated the present value of lifetime productivity loss because of SUD.

RESULTS

SUD incidence rates in the US adults aged 20-64 were 49.3 (95% confidence interval, 41.2-58.3) and 21.7 (95% confidence interval, 16.5-27.8) per 100,000 among men and women, respectively. SUD resulted in the loss of 2 million years of life, accounting for 10.0% of YLL from all causes of death. Among natural causes of death, YLL from SUD was only lower than that from all cancers combined and heart disease. Lifetime productivity loss because of SUD was ~$51 billion, exceeding productivity loss from any individual cancer.

CONCLUSION

SUD is an important source of YLL and productivity loss among adults aged 20-64. Such a high burden on society justifies prioritizing health policies and interventions toward preventing SUD.

Lipid Profiles in Out-of-Hospital Sudden Unexpected Death

Objective

To determine the association between serum lipid measurements and the occurrence of out-of-hospital sudden unexpected death (OHSUD).

Patients and Methods

We compared 139 OHSUD cases (43 female patients [30.9%]) and 968 controls (539 female patients [55.7%]) from Wake County, North Carolina, from March 1, 2013, through February 28, 2015. Individuals were included if they were aged 18 to 64 years and had lipid measurements in the 5 years before their death (cases) or the most recent health care encounter (controls). Covariates were abstracted from medical records for all subjects, and those with triglyceride (TG) levels greater than 400 mg/dL (to convert to mmol/L, multiply by 0.0259) were excluded for low-density lipoprotein (LDL)–related analyses.

Results

By linear regression using age- and sex-adjusted models, cases of OHSUD had lower adjusted mean total cholesterol (170.3±52.2 mg/dL vs 188.9±39.7 mg/dL; P<.001), LDL cholesterol (90.9±39.6 mg/dL vs 109.6±35.2 mg/dL; P<.001), and non–high-density lipoprotein (HDL) (121.6±49.8 mg/dL vs 134.3±39.6 mg/dL; P<.001) levels and a higher adjusted TG/HDL-C ratio (4.7±7 vs 3±2.7; P<.001) than did controls. By logistic regression using age- and sex-adjusted models, the odds of OHSUD were elevated per unit increase in TG/HDL-C ratio (1.08; 95% CI, 1.03-1.12).

Conclusion

Out-of-hospital sudden unexpected death cases had more favorable levels of total cholesterol, LDL cholesterol, and non-HDL, possibly indicating a lack of association between traditional lipid cardiovascular risk factors and sudden unexpected death. A comparatively elevated TG/HDL-C ratio in cases may corroborate an evolving hypothesis of how vasoactive and prothrombotic remnant-like lipoprotein particles contribute to sudden unexpected death.

Medication Use in Women and Men With Sudden Unexpected Death

BACKGROUND

In Wake County, NC, sudden unexpected death accounts for 10% to 15% of all natural deaths in individuals 18 to 64 years old. Medications such as aspirin, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, and β-blockers are recommended in guidelines to reduce cardiovascular events and even sudden death (β-blockers). However, guidelines are often underpracticed, even in high-risk patients, with noted disparities in women.

OBJECTIVE

We assessed the relation between prescription of evidence-based medications and sudden unexpected death in Wake County, NC.

METHODS

We analyzed 399 cases of sudden unexpected death for the time period March 1, 2013 to February 28, 2015 in Wake County, NC. Medications were assessed from available medical examiner reports and medical records and grouped using the third level of the Anatomical Therapeutic Chemical Classification System (ATC) codes. This study was reviewed and exempt by the University of North Carolina's institutional review board.

RESULTS

Among 126 female and 273 male victims, women were prescribed more medications overall than men (6.5 vs 4.3, P = 0.001); however, the use of guideline-directed therapies was not different between genders in the chronic conditions associated with sudden death. Overall, there was remarkably low use of evidence-based medications.

CONCLUSIONS

Our findings highlight the need to improve prescribing of evidence-based medications and to further explore the relationship between undertreatment and sudden unexpected death.

Exploring links between greenspace and sudden unexpected death: A spatial analysis

Greenspace has been increasingly recognized as having numerous health benefits. However, its effects are unknown concerning sudden unexpected death (SUD), commonly referred to as sudden cardiac death, which constitutes a large proportion of mortality in the United States. Because greenspace can promote physical activity, reduce stress and buffer air pollutants, it may have beneficial effects for people at risk of SUD, such as those with heart disease, hypertension, and diabetes mellitus. Using several spatial techniques, this study explored the relationship between SUD and greenspace. We adjudicated 396 SUD cases that occurred from March 2013 to February 2015 among reports from emergency medical services (EMS) that attended out-of-hospital deaths in Wake County (central North Carolina, USA). We measured multiple greenspace metrics in each census tract, including the percentages of forest, grassland, average tree canopy, tree canopy diversity, near-road tree canopy and greenway density. The associations between SUD incidence and these greenspace metrics were examined using Poisson regression (non-spatial) and Bayesian spatial models. The results from both models indicated that SUD incidence was inversely associated with both greenway density (adjusted risk ratio [RR] = 0.82, 95% credible/ confidence interval [CI]: 0.69-0.97) and the percentage of forest (adjusted RR = 0.90, 95% CI: 0.81-0.99). These results suggest that increases in greenway density by 1 km/km2 and in forest by 10% were associated with a decrease in SUD risk of 18% and 10%, respectively. The inverse relationship was not observed between SUD incidence and other metrics, including grassland, average tree canopy, near-road tree canopy and tree canopy diversity. This study implies that greenspace, specifically greenways and forest, may have beneficial effects for people at risk of SUD. Further studies are needed to investigate potential causal relationships between greenspace and SUD, and potential mechanisms such as promoting physical activity and reducing stress.

Relation of Household Income to Incidence of Sudden Unexpected Death in Wake County, North Carolina

The incidence of out-of-hospital sudden unexpected death (OHSUD) in a racially and socioeconomically diverse population has been inadequately studied. We collated all OHSUDs over a 24-month period among 18- to 64-year olds in Wake County, North Carolina, to investigate geographic and socioeconomic disparity in incidence of OHSUD. An electronic query of Wake County Emergency Medical Services (EMS) identified all EMS attended out-of-hospital deaths. After excluding trauma, expected deaths, and deaths occurring in non-free-living subjects, medical records and medical examiner's reports were reviewed by a committee of cardiologists to make the determination of OHSUD. Victims were geocoded to census tracts, and demographic and socioeconomic data were obtained from the 2014 American Community Survey and 2010 US Census. Incidence was examined by sociodemographic group with univariate analysis and multivariable regression. There were 397 OHSUDs, and 53% of census tracts had >1 event. The incidence of OHSUD was 64 of 100,000; 107 of 100,000 among blacks; and 60 of 100,000 among whites. Census tracts with >1 OHSUD had a higher population of blacks, a greater proportion unmarried, a lower median household income, and a greater proportion residing in a rural area. Only median household income remained a significant predictor of OHSUD after adjustment in multivariable analysis. Low median household income of a community portends a higher incidence of sudden death. In conclusion, interventions to reduce the incidence of sudden death need to be developed with these specific communities in mind.

Estimated incidence and risk factors of sudden unexpected death

OBJECTIVE

In this manuscript, we estimate the incidence and identify risk factors for sudden unexpected death in a socioeconomically and racially diverse population in one county in North Carolina. Estimates of the incidence and risk factors contributing to sudden death vary widely. The Sudden Unexpected Death in North Carolina (SUDDEN) project is a population-based investigation of the incidence and potential causes of sudden death.

METHODS

From 3 March 2013 to 2 March 2014, all out-of-hospital deaths in Wake County, North Carolina, were screened to identify presumed sudden unexpected death among free-living residents between the ages of 18 and 64 years. Death certificate, public and medical records were reviewed and adjudicated to confirm sudden unexpected death cases.

RESULTS

Following adjudication, 190 sudden unexpected deaths including 122 men and 68 women were identified. Estimated incidence was 32.1 per 100 000 person-years overall: 42.7 among men and 22.4 among women. The majority of victims were white, unmarried men over age 55 years, with unwitnessed deaths at home. Hypertension and dyslipidaemia were common in men and women. African-American women dying from sudden unexpected death were over-represented. Women who were under age 55 years with coronary disease accounted for over half of female participants with coronary artery disease.

CONCLUSIONS

The overall estimated incidence of sudden unexpected death may account for approximately 10% of all deaths classified as 'natural'. Women have a lower estimated incidence of sudden unexpected death than men. However, we found no major differences in age or comorbidities between men and women. African-Americans and young women with coronary disease are at risk for sudden unexpected death.