Premature Mortality Patterns Among American Indians in South Dakota, 2000–2010

Background

American Indians in South Dakota have the highest mortality rates in the nation compared to other racial and ethnic groups and American Indians in other states.

Purpose

Cause-related and age-specific mortality patterns among American Indians in South Dakota are identified to guide prevention planning and policy efforts designed to reduce mortality within this population, in both South Dakota and other parts of the U.S.

Methods

Death certificate data from South Dakota (2000–2010), on 5738 American Indians and 70,580 whites, were used to calculate age-specific mortality rates and rate ratios. These values were examined in order to identify patterns among the leading causes of death. Analyses were completed in 2011 and 2012.

Results

Within the South Dakota population, 70% of American Indians died before reaching age 70 years, compared to 25% of whites. Fatal injuries and chronic diseases were the leading causes of premature mortality. Nine leading causes of death showed consistent patterns of mortality disparity between American Indians and whites, with American Indians having significantly higher rates of mortality at lower ages.

Conclusions

Premature mortality among American Indians in South Dakota is a serious public health problem. Unified efforts at the federal, tribal, state, and local levels are needed to reduce premature death within this population.

Introduction

American Indian mortality rates vary substantially across the U.S. Compared to other racial and ethnic groups, American Indians in some states, such as Indiana, Kentucky, and Texas, have the lowest age-adjusted mortality rates in the nation. In other states, however, such as South Dakota, North Dakota, and Kansas, American Indian mortality rates are highest in the nation.¹ In part, this variation reflects tribal and regional differences in morbidity and risk factors. Examination of the validity of race reporting on U.S. death certificates, however, shows substantial under-reporting or misclassification of American Indians' race in some regions of the country.² These reporting issues result in artificially low mortality rates for the American Indian population in the U.S. and contribute to wide misunderstanding about American Indian mortality and health. When rates are adjusted for misclassification, American Indians in the U.S. have substantially higher mortality rates than whites.²

Over the past decade, American Indians in South Dakota had the highest age-adjusted mortality rates in the nation compared to other racial and ethnic groups, and to American Indians in other states.1, 3 Vital records data show that about 500–600 American Indian residents die in South Dakota each year. Annual age-adjusted mortality rates during 2000–2010 fluctuated between 1480 and 1179 per 100,000 people. These annual rates typically approached double the combined rates for all U.S. citizens.

In 2010, three South Dakota counties had the highest poverty rates in the U.S., with more than 47% of county residents living in poverty compared to 15% for the national county average.⁴ These three counties are home to three American Indian reservations. Living in environmental circumstances of poverty, unemployment, and insecurity increases the likelihood of risk factors that directly affect premature mortality and morbidity. In addition, smoking, obesity, and alcohol abuse are leading preventable risk factors for death and disability.⁵ In South Dakota, these risk factors are prevalent among American Indians. In the 2010 Behavioral Risk Factor Surveillance System, 48% of American Indian adults were current smokers, and 43% were obese. Further, the northern plains Indian Health Service statistical region, including South Dakota, had an alcohol-attributable death rate more than three times that in the U.S. general population.⁶

High rates of American Indian mortality and morbidity are not unique to South Dakota. Previous studies have identified high rates of injury mortality, which is strongly associated with alcohol abuse,⁶ among American Indians across the U.S.⁷ Diabetes prevalence is also higher within the U.S. American Indian population compared to the total U.S. population.⁸ Moreover, the National Health Interview Survey in 2011 found 32% of American Indians across the U.S. were current smokers compared to 19% of the total population.⁹ Smoking is the leading cause of preventable death in the U.S., and American Indians have significantly higher rates of smoking than do blacks, whites, Asians, and Latinos.⁹

Smoking, obesity, and alcohol abuse increase risk of early mortality from chronic diseases, including heart disease, stroke, cancer, diabetes, liver disease, respiratory diseases, influenza, and pneumonia.6, 10, 11, 12 Alcohol abuse is the leading preventable risk factor for intentional and unintentional injuries, including car crashes, suicides, and homicides.⁶ Thus, the data presented here may be helpful in guiding health policy and prevention efforts designed to reduce American Indian mortality in South Dakota and across the U.S. Death certificate data from South Dakota's vital records database were analyzed to understand the leading causes of death, and age-specific mortality patterns. This information provides public health programs with a reference point so that future death certificate data can be used to track progress toward reducing American Indian mortality rates across leading causes and within at-risk age groups.