Trends in unintentional injury mortality among American Indians/Alaska Natives in Washington, 1999-2009

Background: American Indians and Alaska Natives (AI/ANs) experience excess mortality from unintentional injuries compared with the general population, and injury prevention has become a priority area for many Indian health programs. To assess whether injury mortality rates have changed over time, we examined data from Washington death certificates. Methods: We calculated age-adjusted rates per 100,000 and trends for unintentional injury deaths for the period 1999-2009. Cases were selected using ICD-10 underlying cause of death codes. We used two-year rate averages for trend analysis; statistical significance was assessed with linear regression and annual percent change (APC) was used as a measure of magnitude. Prior to analysis, we corrected race information in death records using probabilistic linkage to a file representing Washington's urban and tribal AI/AN population. Results: From 1999 to 2009, there were 966 AI/AN and 22,302 white unintentional injury deaths. On average, age-adjusted rates for AI/ANs increased 8.0% per year (p=0.05), compared with 5.0% for whites (p<0.01). Increasing trends were seen in unintentional poisoning deaths among AI/ANs: drug overdose mortality increased 27.2% (p=0.06) and narcotic overdoses increased 18.5% annually (p=0.02). Although not statistically significant, we saw evidence of increasing fall-related mortality and decreasing drowning deaths among AI/AN. Whites had a statistically significant decrease in motor vehicle accident mortality (APC=-6.25%, p=0.02), while AI/ANs did not show any significant change (APC=2.8%, p=0.33). Conclusions: Our findings point to increasing trends and disparities in AI/AN unintentional injury mortality over a recent time period. These data may inform injury prevention activities in Indian Country.