https://orcid.org/0000-0003-3497-1641
Abstract
The present study aims to compare Years of Life Lost for unintentional drug overdose and the leading underlying causes of death in the United States annually from 2017 to 2019. Years of Life Lost provide valuable context to incident deaths when comparing the relative mortality burden of underlying causes of death. Prior research has shown unintentional drug overdose was the third leading cause of Years of Life Lost in the state of Ohio in 2017. However, this finding has yet to be replicated at the national level in the US. Death statistics for 2017–2019 were accessed via CDC WONDER. Years of Life Lost were calculated for unintentional drug overdose and each of the top five causes of incident deaths in the US during the study period. Unintentional drug overdose caused nearly seven million Years of Life Lost in the US during the three-year period of study and was the fourth leading cause of Years of Life Lost after cancer, heart disease and other accidents. Incidence alone provides an incomplete picture of the effect of unintentional drug overdose on overall mortality burden in the US. Years of Life Lost give critical context to the overdose crisis, underscoring unintentional drug overdose as a leading cause of premature mortality.
Background
The United States (US) continues to experience a crisis of unintentional drug overdose mortality.Citation1,Citation2 Of particular societal concern is the fact that unintentional drug overdose primarily affects younger individuals, each of whom loses many years of economic participation as well as community and family life.Citation3,Citation4 Therefore, epidemiological reports including only incident deaths fail to capture the true magnitude of the overdose crisis. The World Health Organization has made it clear on how incident death is not an adequate metric for understanding mortality burden and suggests the use of Years of Life Lost (YLL) instead.Citation5 It has been asserted that calculating Years of Life Lost (YLL) provides valuable context to incident deaths, particularly when comparing mortality burden between clinical entities that occur, on average, at different points in the lifespan.Citation6–8 For example, a recent report by our group showed that unintentional drug overdose was the 3rd leading cause of YLL in Ohio in 2017, just after cancer and heart disease, despite causing significantly fewer incident deaths.Citation3 However, this state-level analysis, which employed data from the Ohio Department of Health, requires replication at the national level with a larger dataset. Therefore, the aim of this study was to replicate and extend our previous work by comparing YLL due to unintentional drug overdose to known leading underlying causes of death (UCD) in the US.
Methods
This cross-sectional retrospective study utilized summary death statistics for the years 2017, 2018 and 2019 obtained from the Centers for Disease Control (CDC) Wide-ranging Online Data for Epidemiologic Research (WONDER) mortality file.Citation9 Our procedure was as follows. First, WONDER was queried for a ranked list of the 15 leading UCD in the US for each calendar year 2017–2019. Second, total YLL were calculated for each of the top 5 UCD that year. YLL were calculated by subtracting the age at death from the standard life expectancy for each decedent (YLL = standard life expectancy − age at death). Cases were stratified by single-year age and sex. Male and female life expectancy at each individual age was determined from the 2017 Social Security Administration Period Life Table.Citation10 Fourth, WONDER was queried for unintentional drug overdose fatalities in the US during each calendar year 2017–2019. Cases were identified by International Classification of Diseases, Tenth Revision (ICD-10) codes (X40–X44). Fifth, YLL were calculated for unintentional overdose decedents as described above. Sixth, because unintentional overdose is conventionally included in the UCD Accidents category, total YLL due to unintentional overdose was subtracted from UCD Accidents YLL to give YLL for all accidents excluding unintentional overdose (hereafter referred to as “other accidents”). Finally, the top 5 leading UCD (with accidents now split into unintentional drug overdose and other accidents) were re-ranked by YLL.
This study was deemed exempt by the Ohio State University Wexner Medical Center Institutional Review Board.
Results
US comparative mortality 2017
In the US, 2,813,503 deaths occurred due to any cause in 2017. One hundred twenty-nine records required exclusion due to unknown age at death. All-cause YLL were 42,428,035. Unintentional drug overdose accounted for 61,311 deaths and 2,344,176 YLL, representing 2.18% of deaths and 5.53% of total annual YLL. Unintentional drug overdose was the 4th leading cause of YLL after malignant neoplasms, heart disease and other accidents. shows unintentional overdose ranked among the top 5 leading causes of YLL in the US in 2017.
Figure 1. Underlying causes of death in the United States, 2017–2019.
US comparative mortality 2018
In the US, 2,839,205 deaths occurred due to any cause in 2018. One hundred forty-four records required exclusion due to unknown age at death. All-cause YLL were 42,457,442. Unintentional drug overdose accounted for 58,908 deaths and 2,219,805 YLL, representing 2.07% of deaths and 5.23% of total annual YLL. Unintentional drug overdose was the 4th leading cause of YLL after malignant neoplasms, heart disease and other accidents ().
Table 1. Top causes of YLL in the United States 2017–2019.
US comparative mortality 2019
In the US, 2,854,838 deaths occurred due to any cause in 2019. One hundred forty-seven records required exclusion due to unknown age at death. All-cause YLL were 42,601,785. Unintentional drug overdose accounted for 62,172 deaths and 2,319,973 YLL, representing 2.18% of deaths and 5.45% of total annual YLL. Unintentional drug overdose was the 4th leading cause of YLL after malignant neoplasms, heart disease and other accidents.
Comparative gender mortality
Over the study period males lost two-fold the YLL as females to unintentional drug overdose, with males losing 4,661,175.20 and females losing 2,222,777.68 years. Overdose mortality decreased slightly for females during the study going from 766,520.22 to 732955.09. Whereas male YLL increased from 1,577,655.41 to 1587017.48. With analysis by gender, unintentional drug overdose for females was the 6th leading cause of YLL after cerebrovascular diseases. Conversely, for males it was the 4th leading cause of death like overall yearly totals above.
Discussion
Unintentional drug overdose contributed significantly to overall mortality burden in the US, causing nearly seven million YLL during the three-year period of study. This preventable cause of death ranked fourth in the nation among leading sources of YLL each year between 2017 and 2019. These results replicate and extend our previous work detailing overdose mortality.Citation3,Citation11–14 By calculating YLL, we have shown unintentional drug overdose caused a mortality burden comparable in scale to known leading causes of incident deaths, despite relatively fewer cases annually. The observed discrepancy between number of incident deaths and YLL underscores the fact that unlike leading UCDs malignancy and heart disease, unintentional drug overdose primarily affects younger individuals, depriving individuals and society of a disproportionately greater number of years of work, community and family life.
The present work should be read considering existing overdose mortality literature. To our knowledge, no prior study has compared unintentional drug overdose YLL to YLL from the leading causes of incident deaths in the US. One study calculated YLL due to unintentional opioid overdose 2001–2016, finding opioid-related deaths accounted for over 1.6 million YLL in in the US in 2016.Citation15 However, this study was limited in that it did not include overdose deaths involving other substances, such as methamphetamine and benzodiazepines which have increasingly contributed to overdose mortality.Citation16,Citation17 Implications of the present work include recommendations for epidemiological studies of drug overdose. Unintentional drug overdoses should be reported separately from other accidents in epidemiological research. Similarly, unintentional drug overdose YLL should be presented alongside incident deaths to better contextualize the overdose crisis. Finally, unintentional drug overdose YLL should be serially assessed in the US and compared with other causes of death. The current practice of including unintentional drug overdose within the category of accidents and failing to contextualize incident deaths with YLL or compare unintentional drug overdose YLL to other causes of death effectively obscures drug overdose as a leading cause of preventable mortality. The authors speculate our recommendations might increase understanding of unintentional drug overdose’s contribution to overall mortality burden in the US and perhaps lead to increased funding for addiction research and treatment.
While this study had strengths including the use of a large national dataset and YLL there were notable limitations. This study focused exclusively on unintentional overdose deaths. Therefore, it underestimates the total mortality burden attributable to drug overdose by excluding deaths due to intentional drug overdose, drug overdose with unclear intent, drug-related physical injuries, assaults, infections, and other medical complications. Finally, vital statistics may be susceptible to incomplete UCD reporting leading to possible undercounting of deaths due to unintentional overdose.Citation18 In conclusion, incidence alone provides an incomplete picture of the effect of unintentional drug overdose on overall mortality burden in the US. YLL give critical context to the overdose crisis, underscoring unintentional drug overdose as a leading cause of excess mortality.
Author contribution
Stephanie Garcia: Investigation, Data curation, Formal analysis, Writing – review & editing.
Julie Teater: Writing – review & editing, Resources.
Candice Trimble: Data curation, Writing – review & editing.
Parker Entrup: Writing – review & editing, Data curation, project administration
Orman E. Hall: Conceptualization, Methodology, Writing – review & editing.
O. Trent Hall: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Writing – original draft, Writing, Writing – review & editing, Visualization, Project administration, Supervision.
| Abbreviations | ||
| YLL | = | years of life lost |
| US | = | United States of America |
| CDC | = | Centers for Disease Control |
| WONDER | = | wide-ranging online data for epidemiologic research |
| UCD | = | underlying causes of death |
| ICD-10 | = | International Classification of Diseases, Tenth Revision |
| Non-OD Accidents | = | all accidental deaths excluding unintentional overdose |
| UOD | = | unintentional drug overdose |
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
There is no funding source to declare.
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