Mortality following myocardial infarction in women and men: an analysis of insurance claims data from inpatient hospitalizations

Abstract

Introduction: The results of previous studies of the association between gender and mortality following hospital admission due to acute myocardial infarction are inconsistent. National data for Germany have been lacking to date. Hence the objective of this study was to analyze this association on the basis of a nationwide dataset.

Methods: The analysis was carried out using insurance claims data from inpatients insured by the statutory health insurer AOK, whose main diagnosis was acute myocardial infarction and who were discharged from hospital in the years 2004 and 2005. Several mortality endpoints were used, including 30-day mortality and one-year mortality.

Results: 132 774 male and female patients were included. Crude analyses showed a pronounced excess mortality in women (odds ratio 30-day mortality = 1.65; 95% confidence interval = 1.59 to 1.70). However, after adjustment for age (in decentiles) practically equal mortality was observed for female and male patients (odds ratio 30-day mortality = 1.00; 95% confidence interval = 0.96 to 1.03). Only in the comparatively small group of male and female patients up to the age of 50 was a slightly increased mortality observed in women (odds ratio 30-day mortality = 1.09; 95% confidence interval = 0.85 to 1.40).

Discussion: To our knowledge, this study is the first nationwide analysis focusing on the association between gender and survival following hospital admission due to acute myocardial infarction. Different results from earlier regional studies may be explained by selection bias or inadequate risk adjustment.

Keywords: cardiology; gender studies; health service research; mortality; myocardial infarction.

Figure 1

The age-adjusted^* odds ratio of women versus men for 30-day mortality after acute myocardial infarction for each four-position ICD-10 code, AOK patients, 2004–2005 ^* adjusted by age in decentiles. Men were taken as the reference population for statistical purposes, i.e., an odds ratio greater than 1 indicates a higher mortality among women, an odds ratio of 1 indicates equal mortality among men and women, and an odds ratio less than 1 indicates a lower mortality among women. I210: acute transmural anterior wall myocardial infarction, I211: acute transmural posterior wall myocardial infarction, I212: acute transmural myocardial infarction at other locations, I213: acute transmural myocardial infarction at an unspecified location, I214: acute subendocardial myocardial infarction, I219: acute myocardial infarction, not otherwise specified

Figure 2

The age-adjusted^*1 odds ratio of women versus men in different age groups for 30-day mortality after acute myocardial infarction for each four-position ICD-10 code, AOK patients, 2004–2005 ^*1 adjusted by age in years. Men were taken as the reference population for statistical purposes, i.e., an odds ratio greater than 1 indicates a higher mortality among women, an odds ratio of 1 indicates equal mortality among men and women, and an odds ratio less than 1 indicates a lower mortality among women. ^*2 Each age group includes the age groups further to the left, e.g., the "<50" age group includes all patients under age 50 and thus contains within it the "<40" age group, etc.