Research article
Opioid Analgesics and Rates of Fatal Drug Poisoning in the United States

https://doi.org/10.1016/j.amepre.2006.08.017Get rights and content

Objective

To determine whether the variability in rate of sale of prescription opioid analgesics is related to the variability in rates of drug poisoning mortality among states in the United States in 2002.

Methods

Drug poisoning deaths were defined as unintentional deaths or those of undetermined intent whose underlying cause was coded to “narcotics” (X42) or “other and unspecified” drugs (X44) in the National Vital Statistics System. Per capita sales of ten opioid analgesics from the Drug Enforcement Administration and combined sales in morphine equivalents were correlated with drug poisoning mortality rates by state using multivariate linear regression. Regression coefficients between mortality rates and sales rates were adjusted for race (percent white, percent black) and age (percent aged 24 years or younger, and percent aged 65 years and older).

Results

There was over a ten-fold variability in sales of some opioid analgesics. Combined sales ranged 3.7-fold, from 218 mg per person in South Dakota to 798 mg per person in Maine. Drug poisoning mortality varied 7.9-fold, from 1.6/100,000 in Iowa to 12.4/100,000 in New Mexico. Drug poisoning mortality correlated most strongly with non-OxyContin® oxycodone (r=0.73, p<0.0001), total oxycodone (r=0.68, p<0.0001), and total methadone (r=0.66, p<0.0001) in the multivariate analysis. A scatterplot demonstrated a linear relationship between total opioid analgesic sales and drug poisoning mortality.

Conclusions

The extent of opioid analgesics use varies widely in the United States. Variation in the availability of opioid analgesics is related to the spatial distribution of drug poisoning mortality by state.

Introduction

Information derived from the National Vital Statistics System indicates that the age-adjusted rate of fatal unintentional poisoning from drugs, both licit and illicit, rose from 1.8 per 100,000 in 1990 to 5.7 per 100,000 in 2002, an increase of 218%. Among the 16,394 unintentional drug poisoning deaths in 2002, the vast majority (92.2%) are categorized based on information on the death certificates as due to “narcotics,” mixtures of different types of drugs, or unspecified drugs.1 Unfortunately, these nonspecific categories are not helpful in determining the relative contributions of prescription and illicit or street drugs to this dramatic increase in mortality.

Individual states within the United States, however, have also reported local increases in drug poisoning deaths between 1990 and 2002.2, 3, 4, 5 Some with access to the results of medical examiner or coroner investigations6, 7 report that prescription opioid analgesics are the most commonly encountered prescription drugs involved, and that opioid analgesics (including methadone) are more commonly encountered than illicit drugs such as heroin or cocaine. Like people dying from overdoses of illicit drugs, many of the victims of opioid analgesic poisoning are noted to have a history of substance abuse.2, 3, 6

Reports from the medical examiner program of the Drug Abuse Warning Network (DAWN) also note an increase in the number of deaths involving opioid analgesics in participating cities.8 Published data from DAWN are not aggregated across cities, however, and are not nationally representative. Therefore, neither individual state reports nor DAWN data can shed light on the important question of how large a role opioid analgesics now play in the epidemic of drug poisoning deaths in the United States. It also remains unclear which prescription opioid analgesics are most often implicated in these deaths.

This study hypothesized that if widespread use of opioid analgesics contributed substantially to national drug poisoning mortality by 2002, then states with heavier use of opioid analgesics should have higher rates of drug poisoning. If, on the other hand, opioid analgesics were a problem only in selected states and had a minor role nationwide when compared to other drugs such as heroin and cocaine, then no association or only a weak association would exist between opioid analgesic usage and drug-poisoning mortality rates. The strength of the association between sales of a particular opioid analgesic and drug-poisoning mortality rates among states would also provide some measure of the relative contributions of different opioid analgesics to these fatal poisonings. Determining whether usage was associated with poisoning mortality was one of the suggestions made by the expert panel that reviewed methadone-associated deaths in 2003.9 This study addressed the need for providing the data for methadone and for all other major types of opioid analgesics.

Section snippets

Methods

Information about drug poisoning deaths came from death certificates compiled by the National Center for Health Statistics (NCHS), part of the Centers for Disease Control and Prevention (CDC). Data from 2002 was the latest available at the time of analysis in 2005. Drug poisoning deaths were selectively defined in this paper as those whose underlying cause was coded to the International Classification of Diseases, Tenth Revision (ICD-10) codes of X42 and Y12, “narcotics and psychodysleptics” or

Results

State drug poisoning mortality rates as defined in this study varied over 7.9-fold from 1.6/100,000 in Iowa to 12.4/100,000 in New Mexico (Figure 1). Rates were lowest in the Midwest and highest in the Southwest, the Mid-Atlantic region, and New England. The national mortality rate and the mean state mortality rate were both 6.3/100,000.

The distributions of opioid analgesic sales per 100,000 population also varied widely by state in 2002 (Table 1). Methadone analgesic distributions ranged

Discussion and Conclusion

Both the drug-poisoning mortality rate as defined for this study and per capita sales of opioid analgesics varied widely among states in 2002. There was a strong, statistically significant correlation between states with the highest drug-poisoning mortality rates and states with the highest overall consumption of opioid analgesics. The correlation between mortality and sales was greatest for oxycodone and methadone.

No previous studies have noted this wide variation in sales of opioid analgesics

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