Between 1987 and 2008, a total of 30,985 fatal or non-fatal hospitalized acute MI events (based on stratified random sample of 20,075 hospitalizations investigated) occurred among residents age 35 through 74 years in the four study communities in ARIC (). Of these, 69% were in persons with no recorded history of MI. There were an estimated 8158 deaths due to CHD (on the basis of 7063 deaths sampled), including both in-hospital and out-of-hospital deaths.
The average annual percent age-and race-adjusted decline (95 percent confidence interval [CI]) in rates of death due to CHD was 5.7 percent (95% CI: −6.1, −5.3) in men and 5.2 percent (95% CI: −5.8, −4.6) in women ( and ). Among men, the decline was non-linear, with the decline steeper in the latter half of the study period (1997 through 2008) than in the first 10 years (1987 through 1996), −8.6 percent (95% CI: −9.7, −7.5) per year and −3.4 percent (95% CI: −4.3, −2.4) per year, respectively (p<0.01). The overall downward age-adjusted trend in total CHD mortality among men was statistically significant in both ARIC black men (−3.2 percent (95% CI: −4.1, −2.2) per year) and ARIC white men (−6.5 percent (95% CI: −7.0, −6.1) per year), with the percent decline per year among ARIC white men generally about twice that of ARIC black men regardless of time period. Of note, is the statistically significant age-adjusted decline in total CHD mortality rates of 5.3 percent (95% CI: −7.5, −3.2) per year among ARIC black men from 1997 through 2008 compared to a non-statistically significant decline of just 0.9 percent (95% CI: −3.3, 1.5) per year in the preceding 10 years from 1987 through 1996. Among women, the age- and race-adjusted trends in total CHD mortality rates were generally similar to those in men (i.e. downward trends in rates greater in the more recent period (p<0.01)). The age-adjusted trends in CHD deaths not preceded by a MI history mirrored those of total CHD mortality.
Rates of out-of-hospital and in-hospital mortality due to CHD declined significantly among both men and women ( and ). Age- and race-adjusted declines in rates of out-of-hospital mortality due to CHD were smaller in percentage compared to in-hospital CHD deaths. Adjusted percent declines in both in-hospital and out-of-hospital CHD death rates were substantially greater in the more recent time period (1997 through 2008) compared to the previous decade (1987 through 1996).
Among men and women, the age- and biomarker-adjusted rate of combined first hospitalization for acute MI or fatal CHD among patients with no history of MI had a significant age-adjusted decline from 1987 to 2008 ( and and ). The overall age-adjusted trend predicted by the fitted quadratic models in annual incidence rates showed a decline of 4.9 percent (95% CI: −5.3, −4.5) per year among ARIC white men, 3.9 percent (95% CI: −4.5, −3.4) per year among ARIC white women, 3.5 percent (95% CI: −4.4, −2.6) per year among ARIC black women, and 1.8 percent (95% CI: −2.6, −1.0) per year among ARIC black men. The average trend for the two decades separately from quadratic regressions models show that the decline in incidence of MI and fatal CHD was generally twice as large in the latter decade compared to the first decade. The difference in the average annual percent change between the two decades was statistically significant for ARIC white men and women (p<0.01). However, the trends comparing the first and second decade among ARIC black men and women did not reach statistical significance (p>0.10). Nevertheless, age-adjusted declines in biomarker adjusted MI and fatal CHD incidence were statistically significant in all four race-gender groups in the most recent time period (1996 through 2008).
The age- and biomarker-adjusted incidence of hospitalizations for MI had significant adjusted declines over the 22-year period. The overall downward trend showed a similar pattern to the trend in combined incident hospitalized MI and fatal CHD, although a test for differences in the average change in trends between the decades did not reach statistical significance. Of note is that among black men and women in ARIC, the lack of a statistically significant downward trend in first hospitalized MI in the earlier time period transitioned to significant declines in MI incidence during the more recent period (1997 through 2008), of −2.5 percent (95% CI: −4.7, −0.4) per year and −3.3 percent (95% CI: −5.8, −0.8) per year, respectively. An examination of trends in recurrent MI revealed significant declines overall, with the declines in men in the period 1997 through 2008 greater than in the earlier decade (p<0.01).
The impact of biomarker change adjustment was particularly notable in investigating trends within and across race-gender groups ( and ). The statistically significant declines in incidence of hospitalized MI events among ARIC blacks in the most recent time period found in the biomarker adjusted rates were masked when shifts in biomarkers were not considered. For example, the age-adjusted average annual percent change in first hospitalized MI over the 22-year surveillance period among black men in ARIC showed an increase of 1.0 percent (95% CI: −0.1, 2.1) per year before accounting for the use of more sensitive biomarkers. After adjustment for biomarker change over time a significant downward trend of 1.5 percent (95% CI: −2.7, −0.4) per year was revealed.
The annual incidence rate of STEMI had age- and biomarker-adjusted declines among men and women ( and ). For men, the decline was greater in the period from 1997 through 2008 (−8.0 percent (95% CI: −10.4, −5.7) per year) than in the prior decade (−2.0 percent (95% CI: −3.4, −0.5) per year) (p<0.01). The age- and biomarker-adjusted incidence of NSTEMI also declined over the 22-year period. Without biomarker adjustment, the rate of decline in NSTEMI was about half that observed for STEMI.
The trends in 28-day case fatality percentages among hospitalized MI cases are shown in and . The overall decline in 28-day case fatality among men for hospitalized cases was similar in the both decades, although a greater improvement in 28-day case fatality in the more recent decade occurred among black men in ARIC. For men the age- and race adjusted annual percent change in 28-day case fatality for hospitalized MI was −4.4 percent (95% CI: −7.5, −1.2) per year from 1987 to 1996 and −3.3 percent (95% CI: −6.5, −0.2) per year from 1997 to 2007 (). Among women, the significant decline in 28-day case fatality seen from 1987 through 1996 was no longer significant in the more recent decade.
Average annual percent change (95% confidence interval) in proportion of events not surviving 28 days (28 day case fatality), adjusted for age. The ARIC Study 1987 through 2008.
Trends in a modified definition of MI not including biomarkers (presence of evolving diagnostic Q wave patterns on serial electrocardiograms, or as any evidence of any diagnostic Q wave or ST-segment elevation on any electrocardiograms and a history of chest pain of cardiac origin) yielded similar patterns to those seen in and . Accounting for lack of data on out-of-hospital deaths among community residents for whom neither an informant interview or physician questionnaire was available had little effect on the overall patterns of CHD mortality trends. Similarly, adjustment of hospitalized MI events for missing records did not appreciably change the original trend estimates.