Leading Causes of Mortality on the United States – Mexico Border
Introduction
In a collaborative project carried out by the governments of Mexico and the United States and the Pan American Health Organization / World Health Organization (PAHO/WHO), the profiles and trends of mortality were determined for border areas of the United States and Mexico. The publication of this project responded to the need to provide a comprehensive set of detailed reference data on mortality corresponding to smaller geographic areas and to the border area in particular. Although numerous communities have developed on both sides of the border, those with the largest populations were of particular interest and collectively had been designated by the PAHO Field Office/US–Mexico Border in El Paso, Texas, as the "Sister Communities." The counties or municipalities comprising the Sister Communities are shown in Figure 1 and formed the unit of analysis. As part of this project and to enhance the analytical capability in epidemiology of national and local health professionals, a series of five workshops were held in selected Sister Communities along the border to review detailed mortality reference tables and graphs corresponding to the participant’s respective "Sister Communities". Mortality information from each Sister Community was aggregated to form the corresponding border totals reflecting overall mortality. To develop the mortality profiles of the border area, this information was then analyzed for leading causes of death and patterns of mortality in six broad causal groups and categorized by age and sex. The disparities shown in these profiles by cause, sex, and age group among the Sister Communities can be used to indicate potential inequities in the health situation of the populations.
Mortality data, 1990-1994, for border areas of the United States were provided by the National Center for Health Statistics, U.S. Department of Health and Human Services, and those for Mexico were provided by the Dirección General de Estadística e Informática, Secretaría de Salud. Mid-year population estimates provided by the Consejo Nacional de Población (CONAPO) for Mexico and by the United States Bureau of the Census for the United States were used for the calculation of rates. Estimated populations for 1991–1994 were based on projections from the 1990 census in each country. Data corresponding to national, state, and county/municipality levels by sex and cause in seven broad age groups (under one year, 1-4, 5-14, 15-24, 25-44, 45-64 and 65 years and over) were sent by both governments to PAHO’s Special Program for Health Analysis. These data were then integrated into a standardized format, processed, analyzed, and presented in a variety of formats to form a comprehensive set of reference. This information was recently published in the bilingual (English and Spanish) publication Mortality Profiles of the Sister Communities on the United States – Mexico Border, 1992-1994.
Population and General Mortality
In 1994, about 90% of the United States–Mexico border population—an estimated 9.5 million persons lived in one of the 14 pairs of Sister Communities. Population growth during 1990–1994 in the border region has been rapid, averaging about 3.1% per year on the Mexico side of the border and 2.4% per year on the United States side of the border. A grand total of 166,602 deaths were registered during 1992–1994 among the Sister Communities on both sides of the border, corresponding to a crude mortality rate of 6.0 per 1,000 population. Of these, a total of 54,855 deaths were recorded among the Sister Communities of Mexico—a crude death rate of 4.9 per 1,000 population. On the United States side, a total of 111,747 deaths were recorded during 1992–1994, a crude death rate of 6.7 per 1,000 population—a rate 39% higher than that of the Mexican side. However, the age-adjusted mortality rate was 6.6 per 1,000 population on the Mexican border and 4.5 on the United States border (31.4% less). The overall age-adjusted mortality rate for the combined United States–Mexico border region was 5.2 per 1,000 population.
Leading Causes of Death
The proportionate mortality for the five leading causes of death as a percentage of total deaths from defined causes in the United States–Mexico border region is shown by sex in figure 2. Deaths from defined causes exclude causes assigned to the category "symptoms, signs and ill-defined conditions (ICD 9: 780–799)." It should be noted that the leading causes of death depend not only on the relative frequency of deaths in a category but also on the definition of the causal categories that are candidates for ranking. The "short" list used to determine the leading causes of death contained 24 causal groupings of death.
As can be seen in Figure 2, the first five causes of mortality account for about two-thirds of the deaths from defined causes in the total population on the Mexico border and nearly three-fourths (73.6%) of deaths on the United States border. They also account for about 65% of the deaths in males and females from defined causes in border areas of Mexico and for 72% and 76% of male and female deaths, respectively, in border areas of the United States.
In the 1992–1994 period the leading cause of death on the border was diseases of the heart (ICD 9: 390–429). In the Mexican Sister Communities, a total of 9,870 deaths (18.3% of deaths from defined causes) were recorded from heart disease. In contrast, mortality was 3 times greater in United States Sister Communities, with 33,040 deaths (29.9% of deaths from defined causes). Within this disease category, ischemic heart disease (ICD 9: 410–414) accounted for 64.9% of the deaths on the Mexico side and for 64.5% on the United States side. Proportionately, deaths from heart disease were slightly greater among women than men. On the Mexican border, heart disease accounted for a total of 4,292 female deaths (19.9% of female deaths from defined causes) and 5,570 male deaths (17.3% of male deaths from defined causes). On the United States border, heart disease had a much higher toll: 17,195 male deaths (29% of male deaths from defined causes) and 15,845 female deaths (31% of female deaths from defined causes).
Age-adjusted death rates per 100,000 population from the leading causes of death for the Sister Communities are shown geographically in Figure 3. The geographic maps provide the spatial distributions and magnitudes with respect to the leading causes of death and help to identify inequalities in the patterns of mortality. Age-adjusted death rates from heart disease for 1992–1994 were 152.3 per 100,000 males and 127.1 per 100,000 females in Sister Communities of Mexico. These rates were 48.3% and 16.8% higher than corresponding nationwide rates for Mexico: males, 102.7; females, 108.8. In contrast, age-adjusted rates in Sister Communities of the United States of 132.2 in males and 115.0 in females were 20% and 21.9% lower, respectively, than nationwide rates in the United States by sex. The United States Sister Communities also had rates that were 13.2% and 9.5% lower for males and females, respectively, than for their counterparts in Mexico.
Malignant tumors (ICD 9: 140–208) were ranked as the second leading cause of death on both sides of the border, with a total of 6,615 deaths in Sister Communities of Mexico and 26,019 deaths in Sister Communities of the United States. In the border communities of Mexico, malignant tumors accounted for 12.3% of all deaths from defined causes but the proportion was twice that (23.5%) on the United States side. A review of these deaths by tumor site indicates that, on the Mexico border, malignant neoplasms of the digestive organs and peritoneum (ICD 9: 150, 152, 155–159) accounted for 16.5% of deaths from malignant tumors; malignant neoplasms of the trachea, bronchus, and lung (ICD 9: 162) accounted for 16.3%; and malignant neoplasms of the uterus (ICD 9: 179, 180, 182) accounted for 11%. On the United States border, malignant neoplasms of the trachea, bronchus, and lung accounted for 26.2% of all malignant tumors and malignant neoplasms of the female breast (ICD 9: 174) accounted for 8.3% of the total.
Accidents and adverse effects (ICD 9: E800–E949) were the third leading cause of death in the Sister Communities of Mexico, accounting for 6,237 deaths (11.6% of deaths from defined causes). In contrast, this group of causes was the fifth leading cause of death on the United States border, with 5,199 deaths — 4.7% of deaths from defined causes. However, among United States border males, accidents were the third leading cause of death, with 3,747 deaths (6.3% of male deaths from defined causes). Among Mexican border males, accidents ranked second as leading cause of death, with 4,847 deaths (15.1% of male deaths from defined causes). Among Mexican border females, deaths from accidents were the fifth leading cause, with 1,369 deaths (6.3% of female deaths from defined causes). However, among United States border females, accidents were not a leading cause of death. Motor vehicle accidents (ICD 9: E810–E825) accounted for 28.3% of deaths from all accidents on the Mexico side and for 49.3% of deaths in this cause group on the United States side. Also, it is of interest to note that accidents and adverse effects were the leading causes of death in all age groups up to 45 years of age (1–4, 5–14, 15–24, and 25–44) on both sides of the border.
The third leading cause of death in communities on the United States border was cerebrovascular disease, with 7,263 deaths, an age-adjusted rate of 26.7 per 100,000 population. Nationally, the United States rate was 30.5 (14.2% higher). This disease also ranked third as a leading cause of female mortality with 4,240 deaths, an age-adjusted rate of 31.0 per 100,000 population, and it ranked fourth as a cause of male mortality with 3,023 deaths (age-adjusted rate of 22.5) in border communities of the United States. All border communities in the United States showed excess female mortality from cerebrovascular disease, with low masculinity mortality ratios calculated as the ratio of male:female age-adjusted rates
Diabetes mellitus (ICD 9: 250) was the fourth leading cause of death among Mexican communities on the border in 1992–1994. A total of 4,922 deaths were recorded, accounting for 9.2% of the deaths from defined causes. Diabetes was also the fourth leading cause of death among Mexican border males, with 2,273 deaths recorded—7.1% of male deaths from defined causes. It was the third leading cause of death among Mexican border females, with 2,646 deaths or 12.3% of female deaths from defined causes. The following age-adjusted death rates from diabetes were registered for the Mexico border: 68.7 in both sexes, 62.7 in males, and 74.6 in females. Compared with national data, the border rates were 43.7% higher for both sexes, 52.9% higher in males, and 36.1% higher in females. In comparison, diabetes mortality is about one-fifth the amount in areas of the United States border, with an age-adjusted rate of 11.3 per 100,000 population. Compared with United States national data, age-adjusted rates on the border were smaller—about 3% overall (11.7 vs. 11.3), 2% in males, and 6% in females.
The fourth leading cause of death in the United States border communities was chronic obstructive pulmonary disease (ICD 9: 490–496), with 5,581 deaths, causing 5% of total deaths from defined causes. Among males in United States border communities, chronic obstructive pulmonary disease (COPD) ranked fifth, with 2,908 deaths (4.9% of male deaths from defined causes); among females it ranked fourth, with 2,673 deaths (5.2% of female deaths from defined causes). Age-adjusted death rates from COPD were 20.4 per 100,000 population and 21.1 in males and 19.6 in females in border communities of the United States. These rates compared with United States national data were similar overall (20.3) but 7.0% lower than males nationally (22.7) and 7.1% higher than females nationally (18.3). Although COPD was not a leading cause of death in the border area of Mexico, it accounted for 1,610 deaths (3.0% of deaths from defined causes). The age-adjusted rate of 23.8 per 100,000 population was 17% higher than in the United States border area. Masculinity mortality ratios show that mortality from COPD is predominant in men on both sides of the border.
Conditions originating in the perinatal period (ICD 9: 760–779) was not only the leading cause of infant mortality on both sides of the border but the fifth leading cause of overall mortality in the border areas of Mexico, accounting for 5.4% of deaths from defined causes.
Publication
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The publication Mortality Profiles of the Sister Communities on the United States – Mexico Border, 1992-1994, from which the previous summary was extracted, provides currently available information on the mortality profiles of the 14 pairs of Sister Communities on the United States-Mexico Border. As previously mentioned, this 304 page bilingual publication is the result of a collaborative project between the governments of Mexico, the United States and PAHO. It includes an analytical section, a series of graphs and geographic maps of mortality and an annex of detailed statistical reference tables. The publication endeavors to draw attention to the importance of generating and using data at different levels: local, state, national and bi-national. |
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Epidemiological Bulletin , Vol.
20 No. 2, June 1999