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Letters
June 2, 2004

Changing Patterns of Risk Factors and Mortality for Coronary Heart Disease Among Alaska Natives, 1979-2002

Author Affiliations
 

Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.

JAMA. 2004;291(21):2545-2546. doi:10.1001/jama.291.21.2545
Changing Patterns of Risk Factors and Mortality for Coronary Heart Disease Among Alaska Natives, 1979-2002

To the Editor. Rates of death from coronary heart disease (CHD) among Alaska Natives have historically been lower than those among nonnative Alaskans.1 However, in light of the impact of Western acculturation (ie, high-fat diet, smoking, and sedentary lifestyle) on the prevalence of heart disease among other Native groups,2 we investigated the possibility of similar recent trends in CHD mortality and risk factors among Alaska Natives.

Methods

To compare trends in CHD mortality and differences in prevalence of CHD risk factors between Alaska Natives and nonnative Alaskans, we analyzed CHD mortality rates from death certificate data and CHD risk factors from Alaska's Behavioral Risk Factor Surveillance System (BRFSS). The BRFSS has been administered in Alaska since 1991, with sample sizes initially exceeding 1500 and currently exceeding 2500 participants annually. The validity of BRFSS measures for CHD risk factors are well substantiated.3 The BRFSS and death certificate data supplement each other in that the former provides an indication of the relative risk of CHD and the latter provides actual CHD mortality rate comparisons between Alaska Natives and nonnative Alaskans.

We used the Alaska Section of Epidemiology death certificate database for 1980-1989 and Alaska Bureau of Vital Statistics data for 1979 and 1990-2002 to determine CHD mortality rates. To increase the sensitivity of determining risk for CHD in the target population, we analyzed CHD (International Classification of Diseases, Ninth Revision codes 410-414, and 429.2; 10th Revision codes I20-I25) mortality based on any mention of the condition on the death certificate, limiting our analysis to Alaska residents aged 40 years or older. Individuals were included in the analysis if their race, sex, and cause of death were recorded (0.9% of records excluded). With the exception of 1979, when contributing causes of death were not available on death certificates, methods of computerizing multiple causes of death were comparable across the entire time period. We adjusted mortality rates for age to the 2000 US standard population using the direct method.

We used Alaska BRFSS self-reported data (1991-2002) to compute prevalence for current smoking, overweight/obesity (body mass index ≥25), diabetes mellitus, hypertension, hypercholesterolemia, and sedentary lifestyle among Alaska Natives and nonnative Alaskans.

Results

Figure 1 shows the trends in CHD mortality rates for Alaska Natives and nonnative Alaskans over 6 time periods. From 1979-1982 to 1999-2002, rates of CHD mortality decreased from 671 to 375 deaths/100 000 among nonnative Alaskans and from 409 to 363 deaths/100 000 among Alaska Natives.

Figure. Trends in Coronary Heart Disease Mortality Rates for Alaska Natives and Nonnative Alaskans by Sex (Age ≥40 y)—Alaska, 1979-2002
Image description not available.
Mortality rates adjusted for age to the 2000 US standard population using the direct method.

During 1979-1982 through 1987-1990, the average rate of CHD mortality was significantly lower for Alaska Native vs nonnative Alaskan men (589 vs 850 deaths/100 000; relative risk [RR], 0.69; 95% confidence interval [CI], 0.50-0.95) and combined sexes (438 vs 591 deaths/100 000; RR, 0.74; 95% CI, 0.57-0.97). It was also lower for women, but not significantly (297 vs 383 deaths/100 000; RR, 0.78; 95% CI, 0.49-1.22). During 1991-1994 through 1999-2002, there were no significant differences in CHD mortality between Alaska Native vs nonnative Alaskan men (566 vs 549 deaths/100 000; RR, 1.03; 95% CI, 0.81-1.32), women (262 vs 301 deaths/100 000; RR, 0.87; 95% CI, 0.61-1.23), or both sexes combined (398 vs 418 deaths/100 000; RR, 0.95; 95% CI, 0.78-1.17).

During 1991-2002, hypertension, overweight/obesity, smoking, and sedentary lifestyle were significantly more prevalent among Alaska Natives than among nonnative Alaskans (Table 1).

Table. Difference in Percentage Prevalence for Coronary Heart Disease Risk Factors Among Alaska Natives vs Nonnative Alaskans Aged 40 Years or Older in the Behavioral Risk Factor Surveillance System—Alaska, 1991-2002
Image description not available.
Comment

The BRFSS data for 1991-2002, the only years for which such data exist in Alaska, reveal higher a prevalence of CHD risk factors among Alaska Natives. Tobacco smoking, introduced to Alaska Natives by Western explorers in the mid-1700s,4 is significantly more prevalent among Alaska Natives than among nonnative Alaskans. Moreover, recent dietary changes among Alaska Natives, as well as modern conveniences such as grocery stores, tap water, electricity, and utility vehicles, have substantially altered the lifestyle of Alaska Natives.5 Correspondingly, sedentary lifestyle and overweight/obesity are now significantly more prevalent among Alaska Natives than among nonnative Alaskans. Consistent with increasing trends in BMI, the prevalence of diabetes mellitus among Alaska Natives is also increasing steadily6; the self-reported prevalence of diabetes among Alaska Natives is now similar to that of nonnative Alaskans. Finally, while hypertension was once rare among Alaska Natives,7 they now have a higher prevalence of hypertension than do nonnative Alaskans.

Alaska Natives were previously at lower risk for death from CHD than were nonnative Alaskans; however, this discrepancy has disappeared. Alaska Natives currently have a higher prevalence of numerous risk factors for CHD compared with nonnative Alaskans.

References
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Middaugh JP. Cardiovascular deaths among Alaskan Natives, 1980-86.  Am J Public Health.1990;80:282-285.PubMed
2.
Alpert JS, Goldberg R, Ockene IS, Taylor P. Heart disease in native Americans.  Cardiology.1991;78:3-12.PubMed
3.
Bowlin SJ, Morrill BD, Nafziger AN, Jenkins PL, Lewis C, Pearson TA. Validity of cardiovascular disease risk factors assessed by telephone survey: the Behavioral Risk Factor Survey.  J Clin Epidemiol.1993;46:561-571.PubMed
4.
Fortuine R. Historical notes on the introduction of tobacco into Alaska.  Alaska Med.1996;38:3-7.PubMed
5.
Adler AI, Boyko EJ, Schraer CD, Murphy NJ. The negative association between traditional physical activities and the prevalence of glucose intolerance in Alaska Natives.  Diabet Med.1996;13:555-560.PubMed
6.
Naylor JL, Schraer CD, Mayer AM, Lanier AP, Treat CA, Murphy NJ. Diabetes among Alaska natives: a review.  Int J Circumpolar Health.2003;62:363-387.PubMed
7.
Scott EM, Griffith IV, Hoskins DD, Whaley RD. Serum cholesterol levels and blood pressure of Alaska Eskimo men.  Lancet.1958;2:667-668.PubMed
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