Unintentional deaths from drug poisoning by urbanization of area—New Mexico, 1994-2003

Morbidity and Mortality Weekly Report, Sept 9, 2005 by N. Shah, M.G. Landen

New Mexico experienced an increase in poisoning deaths during the 1990s (1) and in 2002 was the state with the highest death rate (14.1 per 100,000 population) from unintentional poisoning, more than twice the national rate (6.1) (2). The majority of these unintentional poisoning deaths were caused by ingestion of drugs, including illicit, prescription, and over-the-counter drugs. New Mexico is geographically diverse, with communities ranging from urban centers to sparsely populated counties. To examine the relationship between the types of drugs causing poisoning deaths and the levels of urbanization where the decedents resided, the New Mexico Department of Health analyzed data provided by the New Mexico Office of the Medical Investigator (OMI) for 1994-2003. All counties in New Mexico were classified as metropolitan or micropolitan statistical areas, or as nonstatistical areas, by using 2001-2002 population estimates in accordance with 2003 Office of Management and Budget (OMB) classifications * (3,4). This report summarizes the results of that analysis, which indicated that deaths from illicit-drug poisoning were twice as likely to occur in metropolitan areas as nonmetropolitan areas (i.e., micropolitan and nonstatistical areas combined). However, deaths from prescription-drug poisoning were most likely to occur in micropolitan and nonstatistical areas. Investigation of drug-poisoning deaths by level of urbanization can be useful to public health programs to prevent unintentional drug-poisoning deaths.

OMI is authorized to investigate all deaths in New Mexico that are sudden, unexplained, suspicious, violent, or unattended, and also is contracted to investigate the majority of those types of deaths occurring in federal or tribal jurisdictions. Deaths were determined to have been caused by drugs or poisons on the basis of full autopsy, circumstances of death, investigation of death scene and medical background, and toxicologic evaluation indicating lethal blood concentration of one or more drugs, as evaluated by OMI board-certified forensic pathologists. An unintentional drug-poisoning death was a death ruled by OMI as accidental and caused by a single drug, a combination of drugs, or a combination of drugs and alcohol.

Decedent characteristics (e.g., sex, race/ethnicity, and drugs causing death) were analyzed, and age-adjusted drug-poisoning death rates per 100,000 population by urbanization of area were calculated for 1994-2003. The population denominator for rates was the average population estimate from 1994-2003, calculated from 2000 U.S. standard census data for the year 2000 and from intercensal estimates for the other years (5). For all unintentional drug-poisoning deaths, bivariate and multivariate associations were assessed for urbanization level and selected covariates. Four metropolitan and 14 micropolitan statistical areas were identified; 12 sparsely populated counties that did not meet the OMB definition for metropolitan or micropolitan statistical areas were classified as nonstatistical areas, ([dagger]) Drugs causing death were categorized as illicit drugs (i.e., heroin, cocaine, or methamphetamine), over-the-counter drugs, or prescription drugs (i.e., methadone, other opioid painkiller, tranquilizer/ muscle relaxant, antidepressant, barbiturate, or other prescription drug), according to American Hospital Formulary Service Pharmacologic-Therapeutic classifications (6).

During 1994-2003, a total of 1,982 drug-poisoning deaths were identified in New Mexico; data on four deaths did not include county of decedent residence. Statewide, 71.3% of decedents resided in metropolitan areas, 25.3% in micropolitan areas, and 3.4% in nonstatistical areas (Table 1). Compared with decedents from micropolitan and nonstatistical areas, a significantly larger proportion from metropolitan areas died from heroin overdose (52.6% versus 48.8% and 35.3%, respectively). However, a larger proportion from nonstatistical areas than from metropolitan and micropolitan areas died from any prescription drug (50.0% versus 37.2% and 40.2%) or from opioid painkillers other than methadone (38.2% versus 19.6% and 22.8%).

Illicit drug poisonings had the highest death rate (8.1 per 100,000 population), with a higher poisoning death rate from heroin than from cocaine or methamphetamine (5.8 versus 4.4 and 0.6) (Table 2). The death rate from any prescription drug was 4.4, with the highest rate among prescription drugs from opioid painkillers other than methadone (2.4). Metropolitan areas had the highest rates for all drug-poisoning deaths (12.6 versus 9.5 for micropolitan areas and 7.4 for nonstatistical areas), any illicit drug (9.0 versus 6.8 for micropolitan areas and 4.4 for nonstatistical areas), heroin (6.6 versus 4.7 for micropolitan areas and 2.6 for nonstatistical areas), and cocaine (4.8 versus 3.7 for micropolitan areas and 2.4 for nonstatistical areas). Metropolitan areas also had the highest death rates from methadone (1.6) and over-the-counter drugs (1.0). Nonstatistical areas had the highest death rate from opioid painkillers other than methadone (2.8); micropolitan areas had the highest death rate from alcohol and drug cointoxication (3.7).