Trends and Geographic Patterns in Drug-Poisoning Death Rates in the U.S., 1999–2009.

Background: Drug poisoning mortality has increased substantially in the U.S. over the past 3 decades. Previous studies have described state-level variation and urban–rural differences in drug-poisoning deaths, but variation at the county level has largely not been explored in part because crude county-level death rates are often highly unstable. Purpose: The goal of the study was to use small-area estimation techniques to produce stable county-level estimates of age-adjusted death rates (AADR) associated with drug poisoning for the U.S., 1999–2009, in order to examine geographic and temporal variation. Methods: Population-based observational study using data on 304,087 drug-poisoning deaths in the U.S. from the 1999–2009 National Vital Statistics Multiple Cause of Death Files (analyzed in 2012). Because of the zero-inflated and right-skewed distribution of drug-poisoning death rates, a two-stage modeling procedure was used in which the first stage modeled the probability of observing a death for a given county and year, and the second stage modeled the log-transformed drug-poisoning death rate given that a death occurred. Empirical Bayes estimates of county-level drug-poisoning death rates were mapped to explore temporal and geographic variation. Results: Only 3% of counties had drug-poisoning AADRs greater than ten per 100,000 per year in 1999–2000, compared to 54% in 2008–2009. Drug-poisoning AADRs grew by 394% in rural areas compared to 279% for large central metropolitan counties, but the highest drug-poisoning AADRs were observed in central metropolitan areas from 1999 to 2009. Conclusions: There was substantial geographic variation in drug-poisoning mortality across the U.S. [Copyright &y& Elsevier]