Disease Change and the Role of Medicine: The Navajo Experience

3. Disease Patterns on the Navajo Reservation

Disease Patterns on the Navajo Reservation MORTALITY rates had already declined substantially by the mid1950s when the Public Health Serviceassumed responsibility for services to Indian communities and began to record vital events. Nonetheless, the change in causes of mortality and morbidity that accompanied this decline continued. This transition isillustrated in table 3.1, whichshowsthe proportionate distributionof deaths by cause among Navajos in 1954—1956, 1965—1967, and 1973-1975. The table shows the rapid decline in deaths from influenza, pneumonia, gastroenteritis and diarrhea, and the dramatic increase in accident mortality. Heart disease increases slightly, but because symptoms and ill-defined conditions still constitute about 20 percent of the diagnoses, it may be that the increaseis merely an artifact of better reporting. The pattern of deaths from cancer suggests a certain amount of random fluctuation, and thus ismuch lesscertain than the patterns for major diagnostic categories such as accidents and diarrheal and respiratory diseases. Despite changes since 1955, Navajo mortality still differs from that of the U.S. population in respect of the proportionate contribution of different causes to the overall rate, as the last column in table 3.1 demonstrates. Accidentsof alltypes,particularly from motor vehicles, are far more significant for Navajos than for the population generally. The same istrue for influenza and pneumonia, and for gastroenteritis. Cancer and heart dis1 )cJV TABLE 3.1 PROPORTIONATE DISTRIBUTION AND ESTIMATED RATES OF MAJOR CAUSES OF MORTALITY, NAVAJO AREA, 1954-1975 1954-19563 Accidents Diseases of the heart Malignant neoplasms Influenza & pneumonia (excludingnewborns) Certain diseases of infancy Gastritis, enteritis and diarrheal diseases Estimated crude death rate per 1,000 % 16.8 4.2 3.4 14.2 9.6 10.5 Rate per 100,000 118-134 29-34 24-27 99-114 67-77 74-84 7-8 1965- 1967a % 22.9 6.5 7.4 8.1 7.4 5.6 Rate per 100,000 149-172 42-49 48-56 53-61 48-56 36-42 6.5-7.5 1973-1975b % 31.4 7.6 5.8 5.8 3.0 1.6 Rate per 100,000 188-220 46-53 35-41 35-41 18-21 10-11 6-7 1976 U.S. all races Rate per % 100,000 6.9 43.2 34.5 216.7 21.0 132.3 2.8 17.4 6.3 a USPHS 1971:27 (includes Hopi reservation) b USPHS 1979:94 66 I Disease Patterns ease, however, are less significant among Navajos. Interestingly, the Navajo mortality rate from gastroenteritis in 1973— 1975 (10 to 11 per 100,000 population) was the same as the rate for the general population in 1940, whereas the Navajo death rate from influenza-pneumonia in 1973—1975 was about the same as the rate for the general population in 1960. By contrast, mortality rates from accidents have been higher among Navajos than they have ever been among the general population from 1900 to the present. Moreover, among Navajos this rate is increasing whereas in the general population it has decreased from about 84 per 100,000 in 1900 to 56 in 1970 (see appendix II). The impact of contemporary Navajo mortality patterns has been examined by Carr and Lee (1978), who have shown that in 1973 life expectancy at birth was 58.8 for males and 71.8 for females. Eliminating automobile accidents as a cause of death would add 5.17 years of life at birth for men and 2.7 for women; eliminating all other accidents would add 3.13 years of life at birth for men (data for women were not published); eliminating diseases of the circulatory system would add 3.31 yearsof life for men and 3.70 for women. These patterns differsubstantially from those of the U.S. population and illustrate the enormity of the accident problem among Navajos, especially males. Two other points are worth making. First, life expectancy at one year of age does not differ dramaticallyfrom life expectancy at birth for each sex: 59.6 for males and 72.4 for females. This indicates that infant mortality is no longer the major contributor to diminished life expectancy that it once was.Second,infectious diseases do not appear among the five major causes of diminished life expectancy. Judging from comparative data based upon hospital utilization —that is to say, hospitalized morbidity rather than mortality —infectious and parasitic diseases, accidents, deliveries, and perinatal problems account for most...