Significant variation in mortality trends in substance use disorders among US counties

1. Mortality rates decreased for alcohol use disorders, self-harm, and interpersonal violence between 1980 and 2014.

2. Mortality rates for drug use disorders increased both nationally and in each county over the same period.

Evidence Rating Level: 2 (Good)

Study Rundown: Substance use disorders (alcohol and drug use disorders), self-harm, and interpersonal violence pose a significant healthcare burden in the United States. These can disproportionately impact young and middle-aged adults and have significant geographic variation in their distribution. In this retrospective cohort study, mortality rates from alcohol use disorders, self-harm, and interpersonal violence decreased over the last 25 years nationally. However, greater than 50% of US counties had increased mortality rates for alcohol use disorders and self-harm during this time. For drug use disorders, mortality rates increased nationally and in each county during this same period. Additionally, geographic inequalities across US counties increased for drug use disorders and self-harm.

Overall, the study suggests significant variation in mortality rates and trends for substance use disorders and intentional violence, suggesting greater heterogeneity in these measures across the US. The study is limited by its redistribution algorithms for nonspecific causes of death, making the uncertainty intervals for estimated mortality difficult to quantify, and this may lead to underestimates of the actual heterogeneity between counties. Despite this limitation, this study provides important information for policy makers and healthcare professionals as they allocate resources for appropriate services based on where these services are most needed.

Click to read the study, published in JAMA

Relevant Reading: Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015

In-Depth [retrospective cohort]: This is a retrospective study that utilized data from the National Cancer Center for Health Statistics (NCHS) and population counts from the US Census Bureau, NCHS, and the Human Mortality Database. The analysis utilized the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) cause list and utilized ICD-9 and ICD-10 codes that corresponded to each cause, namely alcohol use disorders, drug use disorders, self-harm and interpersonal violence. Redistribution algorithms were used to reallocate deaths assigned to insufficiently specific or implausible “garbage codes” to plausible alternatives. For the small-area model methodology, Bayesian, spatially explicit mixed-effects regression models were estimated separately for each cause.

The study results demonstrate 2,848,768 deaths due to substance use disorders and intentional injuries in the US between1980 and 2014. This included alcohol use disorders (n = 256,432), drug use disorders (n = 542,501), self-harm (n = 1,289,086), and interpersonal violence (n = 760,749). These significantly varied among counties but overall were reduced for alcohol use disorders (8.1%), self-harm (6.0%), and interpersonal violence (44.9%) and increased for drug use disorders (618.3%). The percentage of counties that saw increased rates of mortality over this time included 65.4% for alcohol use disorders, 74.6% for self-harm, and 6.6% for interpersonal violence. Mortality rates increased in each county for drug use disorders.

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