C. Causes of Death

Causes of Death are tracked through the California Department of Health Services, Center for Health Statistics, Office of Vital Records and can provide information taken from death certificates. In this report, two different mechanisms are used to report death rates. The "crude death rate" is obtained by dividing the total number of deaths by the total population, then multiplying by some convenient basis (e.g. 100,000). This allows one to evaluate the impact of death due to all possible effects, including age. A separate measure, the "Age-Adjusted Death Rate" follows a statistical formula which helps remove the confounding effect of different age compositions of different populations. This allows a comparison of populations and helps to identify causes of death which are higher or lower than expected. Caution should always be used when using data from death certificates due to known inaccuracies in the completion of many listed causes of death.

Table 4.13 and Exhibit 4.7 shows a comparison of the annual death rate in Imperial County compared to California over a five year period, 1991-1995. This is a crude death rate. The lower death rate in Imperial County can probably be attributed to the overall younger population in Imperial County and the rapid growth in the county when compared to California.

California Vital Statistics

Exhibit 4.7: Deaths per 1,000 Population

Table 4.14 compares the top ten causes of death in 1995 in California to the top ten causes of death in Imperial County. Clearly, Diseases of the Heart, Malignant Neoplasms (Cancer), Cerebrovascular Disease (Strokes) and Chronic Obstructive Pulmonary Disease are the top causes of death in both California and Imperial County. Note, however, that California’s Causes of Death #7 through 10 do not correspond with the same rankings in Imperial. Those causes of California deaths are as follows: #7: AIDS, #8: Diabetes, #9: Diseases of the Nervous System, and #10: Homicide.

Tables 4.15 and Exhibits 4.8 and 4.9 compare some of the top causes of death for which National Year 2000 objectives were established compared with age-adjusted rates in Imperial County and California. Three years of data were aggregated to provide a large number of events on which to make comparisons. Each of these causes of death was selected because health promotion or disease prevention activities have been shown to have a positive impact on lowering the incidence of these causes of death. They represent areas of opportunity to improving a community’s health.

Although the rates of the causes of death between Imperial and California and Year 2000 National Objectives differ - with some rates being higher and some being lower - the only difference that falls outside of the 95% confidence limits is Firearm Injuries. The low number of events involving firearm injuries in Imperial undoubtedly influences the stability of the estimate of an accurate death rate for this cause of death. All other causes of death in Imperial fall within the 95% confidence limits of California incidence.

Source: California Vital Statistics 1993-1995

Table 4.14: Top 10 Causes of Death

(Note: Because all vital statistic rates are subject to random variation, the concept of "95% confidence limits" is used to help determine if variation between rates is within expected ranges or is significantly different. The 95% confidence limits depict the range within which the rate would probably occur 95 out of 100 times, if the data were independently acquired on 100 separate occasions. Thus, in five of those 100 data sets, the rate or percent would fall outside the limits and would then be considered significantly different.)

Overall, it is impressive that Imperial County already meets the Year 2000 National Objectives in three areas: All Cancers, Lung Cancer and Female Breast Cancer. However, there are significant differences in the rate at which Hispanics die from cancer which may contribute to the overall lower incidence of cancer in Imperial. Carcinogenesis is a complex process thought to involve multiple steps that occur over a long period of time and which can be triggered by chemical, physical, biologic or genetic occurrences or events. The lower mortality from lung cancer among Hispanics has been attributed in part to a lower prevalence of smoking, particularly among women. Dietary differences are also hypothesized to be attributable to differences in cancer risk and has been especially linked with breast and prostate cancer risk.

Causes of death are entered on death certificates using a coding system, the ICD9, which accounts for very detailed causes of death. In the preceding tables, similar causes of death were grouped together to provide a broader understanding of the causes of death. In order to gain a more detailed picture of causes of death in Imperial County, four specific tables were developed with the top 20 ICD9 codes. These tables are located on pages 26 through 29.

• Imperial County vs. California

When comparing the causes of death in Imperial County and California as illustrated in Table S4.14a, the four categories in which Imperial residents die at a significantly higher rate are:

• Motor vehicle traffic accidents,
• Chronic liver disease and cirrhosis
• All other accidents and adverse effects, and
• Other diseases of the Respiratory system.

The two classifications of "Acute ischaemic heart disease" and "Other forms of chronic ischaemic heart disease" are very close in diagnosis and should probably be combined for evaluation purposes. Differences in the individual rates may be a matter of coding differences. When combined, the rate between Imperial and California are quite similar.

Imperial County Hispanics vs. Imperial County Non-Hispanics

When the County causes of death are separated by Hispanics and compared with Non-Hispanics, differing patterns emerge, as depicted in Table S4.14b.

Imperial County Hispanics: The causes of death which show higher rates for Hispanics are:

• Motor vehicle traffic accidents,
• Chronic liver disease and cirrhosis,
• All other accidents,
• Homicide, and
• Malignant neoplasm of the stomach.

The occurrence of these particular causes of death may in part be attributed to the younger age of the Hispanic population in Imperial as higher frequency of accidents is often related to younger age. The identification of chronic liver disease and cirrhosis as a cause of death also raises the question of the involvement of alcohol in motor vehicle fatalities and other accidents resulting in death. Stomach cancer is one of the few types of cancer which occurs at nearly twice the rate in Hispanics and African Americans, as compared to Non-Hispanic Whites. Thus, this rate is not unexpected.

Imperial County Non-Hispanic: The causes of death which show higher rates for Non-Hispanics are:

• Malignant neoplasm of trachea, bronchus, and lung,
• Other and unspecified pneumonia,
• Other chronic obstructive pulmonary disease and allied conditions, and
• Emphysema.

In general, these causes of death are more commonly attributed to an older population so are not unexpected given the population structure of the non-Hispanic population in Imperial. However, it is of note that these four causes of death, occurring in the top 12 causes of deaths for non-Hispanics overall, are all respiratory-related.

• Imperial County Hispanics vs. California Hispanics vs. California

The one new variation in incidence that emerges from Table S4.14c is the low incidence of diabetes mellitus. It has been recognized that persons of Mexican origin have a higher prevalence of non-insulin dependent diabetes mellitus when compared to the general U.S. population. It appears that a genetic basis is likely. Thus, the rate of deaths caused by diabetes mellitus in Imperial County Hispanics is unexpectedly low at 16.85 per 100,000. The California rate for Hispanics is 31.82 per 100,000. There are several possibilities for this lower rate. It has been suggested that a sizable number of Imperial County Hispanics cross the border to receive care in Mexicali and are thus not reported in Imperial County statistics. We are unable to confirm this hypothesis. It is known that persons with diabetes have a higher incidence of myocardial infarction, congestive heart failure and stroke. We note that both acute ischaemic heart disease and cerebrovascular disease are ranked #1 and #2 for Imperial Hispanics and the rate of occurrence is significantly higher than for California Hispanics as a group. It is also interesting to note that Imperial Non-Hispanics also have a lower rate of diabetes as a cause of death when compared to California Non-Hispanics. The relationship between these cannot be fully determined from these statistics but warrants further examination.

• Imperial County Non-Hispanics vs. California Non-Hispanics vs. California

Table S4.14d is perhaps less useful than the preceding tables because it uses a grouping of "California Non-Hispanics" which includes much more ethnic and racial variation than is found in the grouping of "Imperial County Non-Hispanics." Thus, caution should be used in assigning significance. However, this table continues to emphasize the frequency of respiratory-related causes of death in Imperial County Non-Hispanics. It also reveals that although Imperial Hispanics still have higher frequency of traffic accidents and other accidents as a cause of death Imperial County Non-Hispanics also rank higher in these causes when compared to California.

Prevention Activities: To assist the community in thinking about ways to address the problems identified in these statistics, we have taken the liberty to identify certain causes of death which are amenable to community and/or individual interventions. The leading causes of death in Imperial County cluster in the cardiovascular causes (acute and chronic ischemic heart disease, cerebral vascular disease and other forms of heart disease). The Stanford Healthy Cities Program has followed several California cities and demonstrated the ability of a community to positively impact the health of the population in these disease categories. Attention to smoking cessation, diet and exercise programs also positively affects the disease of the respiratory track as a cause of death. The risk for malignant neoplasms of all parts of the respiratory track are reduced in both non- and former smokers. Secondhand exposure to smoke has more recently been shown to negatively affect a number of respiratory and cardiovascular disease rates. Some communities have sponsored stop-smoking programs such as the national "Smoke Free Day." Low-cost stop-smoking groups have also been shown to be cost-effective.

Several of the top causes of death in Imperial County are related to alcohol use and/or abuse. In addition to the diseases of the liver such as cirrhosis, motor vehicle and possibly all other accidents as a cause of death may be alcohol related. Community-sponsored alcohol use reduction programs could be effective.

Finally, there is clear and compelling evidence that early detection of most cancers improves cure rates and reduces death by cancer. Breast cancer is the best example of a relatively common cancer which can be treated and potentially cured if found at an early stage. Testicular and prostate cancer in men can also be affected by early detection through screening.

Previous | Table of Contents | Forward

© CIRHM