Methods

The Arkansas mortality data for CHD and stroke for the period 1979 through 2007 were obtained from the Health Statistics Branch of the Arkansas Department of Health. The United States mortality data for the same period were obtained from the Centers for Disease Control and Prevention on-line data query system, “Centers for Disease Control and Prevention Wonder.” Data on the prevalence of cigarette smoking in Arkansas were not available for the late 1970s and early 1980s; thus, the annual per capita sales of the cigarette packages was used as a measure of smoking prevalence. These sales have been reported as the exact number of packages sold each year because a state revenue stamp is sold for each package. The import of cigarettes into Arkansas illegally by smuggling or cross border sales was not reflected in these data. The precise extent of illegal sales is not known; however, estimates have ranged from 3% to 7% of the total packages consumed each year. Although illegal sales accounted for only a small portion of the total sales in the distant past, these sales have most probably increased as the cigarette tax increased. The data for the estimates on poverty levels in Arkansas were obtained from the United States Census Web site for 1980 to 2008. The prevalence rates for diabetes, hypertension, obesity, and physical inactivity for Arkansas were obtained from the Arkansas Behavioral Risk Factor Surveillance System.

An ecologic correlation analysis was performed using the existing data for CHD, stroke, per capita cigarette sales, and selected behavioral risk factors. Trends in age-adjusted mortality rates were calculated for CHD and stroke in Arkansas and the entire United States for 1979 through 2007 by dividing the number of cases with the population at risk and then making the appropriate age adjustments. The United States standard population in 2000 was used to adjust for the age differences in the population. The Arkansas population, similar to the United States population, has been aging during the past decade; hence, an age adjustment using the United States standard population in 2000 allowed us to compare the study variables over the years. A simple linear regression analysis was conducted to examine the trends, correlations, and coefficient of determination. The coefficient of determination (R ² ) for the relation between age-adjusted CHD- and stroke-mortality rates and per capita cigarette pack sales for 1979 through 2007 were calculated, because this is a standard measure for assessing the correlation for these types of data. The trends in poverty levels in Arkansas for 1980 to 2008 were examined. The trends in diabetes, hypertension, obesity, and physical inactivity prevalence rates were also calculated for 1993 through 2008. R ² was considered significant if the p value was <0.05.

Results

Deaths from CHD in Arkansas decreased steadily from 1979 to 2007, from 272 to 148 per 100,000 population (p <0.001). These rates are shown in Figure 1 , along with the approximate date when various cardioprotective drugs were approved by the Food and Drug Administration. The slope of the decrease did not change significantly in any particular year; instead, the decrease remained at a nearly constant rate for 20 years. The slope of the decrease was significantly lower in Arkansas (β −3.67, 95% confidence interval [CI] −4.05 to −3.28) compared to the decrease for the United States (β −5.86, 95% CI −6.36 to −5.35).

(a) Ischemic heart disease mortality rates for Arkansas and the United States, 1979 to 2007. (b) Stroke mortality rates for Arkansas and the United States, 1979 to 2007. FDA = Food and Drug Administration.

Significant decreases in the CHD death rates occurred in most age groups. The decrease was most pronounced among adults aged ≥55 years (age range 55 to 64, R ² = 0.899, p <0.001; age range 65 to 74, R ² = 0.954, p <0.001; age range 75 to 84, R ² = 0.950, p <0.001; age ≥85, R ² = 0.743, p <0.001). Only a modest decrease was observed among adults 45 to 54 years old (R ² = 0.554, p <0.001), and no decrease occurred for those <45 years old (R ² = 0.002, p = 0.79).

Next, we examined the relation of the decrease in CHD-related deaths to the per capita cigarette sales in Arkansas. A significant correlation was seen in the decrease in CHD-related deaths with the reduction in cigarette sales (R ² = 0.84, p <0.001; Figure 2 ). This was particularly notable because the prevalence rates for obesity (R ² = 0.97, p <0.001), hypertension (R ² = 0.83, p = 0.002), and diabetes mellitus (R ² = 0.84, p <0.001) continued to increase during the latter half of the study period, and the prevalence of physical inactivity marginally decreased (R ² = 0.29, p = 0.07; Figure 3 ).

(a) Ischemic heart disease mortality rates and per capita cigarette pack sales in Arkansas, 1979 to 2007. (b) Stroke mortality rates and per capita cigarette pack sales in Arkansas, 1979 to 2007.

Prevalence of select risk factors, Arkansas, 1993 to 2008.

An analysis of deaths related to stroke showed a pattern similar to that for CHD-related deaths during the same period, decreasing from 118 to 57 per 100,000 population (p <0.001). These rates were greater than the national stroke death rates (p <0.001) at all points. The slope of the decrease in Arkansas (β −1.62, 95% CI −1.88 to −1.37) tracked closely with the decrease in the United States (β −1.57, 95% CI −1.78 to −1.36; Figure 1 ).

The decrease in stroke-related death rates was observed in almost all age groups and was most pronounced in adults aged ≥55 years (age range 55 to 64, R ² = 0.681, p <0.001; age range 65 to 74, R ² = 0.845, p <0.001; age range 75 to 84, R ² = 0.862, p <0.001; age ≥85, R ² = 0.764, p <0.001). Only a modest decrease occurred in the stroke-related death rates for adults aged 45 to 54 years (R ² = 0.415, p <0.001). Finally, the rates for adults <45 years old showed no significant change (R ² = 0.028, p = 0.98).

A marked correlation in the decrease in stroke-related deaths with the reduction in the cigarette packs sold was observed (R ² = 0.76, p <0.001; Figure 2 ). This was particularly striking because the prevalence rates for obesity, hypertension, and diabetes mellitus continued to increase during the latter half of the study period.

Poverty is a risk factor for CHD- and stroke-related deaths, and the poverty level is greater in Arkansas than for the United States as a whole. The percentage of those living in poverty increased and decreased during the study period from a high of 24.1% in 1981 to a low of 13.8% in 2005 and 2007. The trend for the entire period was toward a decrease in the poverty level, and this trend was statistically significant (p <0.001).