In-hospital mortality among patients with type 2 diabetes mellitus and acute myocardial infarction: results from the national inpatient sample, 2000-2010

Abstract

Background: Case-fatality rates in acute myocardial infarction (AMI) have significantly decreased; however, the prevalence of diabetes mellitus (DM), a risk factor for AMI, has increased. The purposes of the present study were to assess the prevalence and clinical impact of DM among patients hospitalized with AMI and to estimate the impact of important clinical characteristics associated with in-hospital mortality in patients with AMI and DM.

Methods and results: We used the National Inpatient Sample to estimate trends in DM prevalence and in-hospital mortality among 1.5 million patients with AMI from 2000 to 2010, using survey data-analysis methods. Clinical characteristics associated with in-hospital mortality were identified using multivariable logistic regression. There was a significant increase in DM prevalence among AMI patients (year 2000, 22.2%; year 2010, 29.6%, Ptrend<0.0001). AMI patients with DM tended to be older and female and to have more cardiovascular risk factors. However, age-standardized mortality decreased significantly from 2000 (8.48%) to 2010 (4.95%) (Ptrend<0.0001). DM remained independently associated with mortality (adjusted odds ratio 1.069, 95% CI 1.051 to 1.087; P<0.0001). The adverse impact of DM on in-hospital mortality was unchanged over time. Decreased death risk over time was greatest among women and elderly patients. Among younger patients of both sexes, there was a leveling off of this decrease in more recent years.

Conclusions: Despite increasing DM prevalence and disease burden among AMI patients, in-hospital mortality declined significantly from 2000 to 2010. The adverse impact of DM on mortality remained unchanged overall over time but was age and sex dependent.

Keywords: Diabetes mellitus; mortality; myocardial infarction.

Figure 1.

National Inpatient Sample activity, 2000–2010. Participation by states increased over time. Sampling methodology maintained the number of hospitals and discharges within a narrow range from 2000 to 2010.

Figure 2.

Prevalence of T2DM over time in patients with AMI. Steady and significant increase in prevalence of T2DM among patients with AMI from 2000 to 2010. AMI indicates acute myocardial infarction; T2DM, type 2 diabetes mellitus.

Figure 3.

Frequency of coronary revascularization during hospitalization. From 2000 to 2010, there was a 23% increase in the use of coronary revascularization procedures in patients with acute myocardial infarction and type 2 diabetes mellitus. The majority (>75%) of these procedures were percutaneous coronary interventions.

Figure 4.

Decrease in crude and age‐standardized mortality rates by sex. Crude and age‐standardized mortality rates in both men and women decreased significantly from 2000 to 2010.

Figure 5.

Effect modification of time (year) by sex. Probability of death plotted against time stratified by sex. The nonparallel nature of the plots is consistent with a statistically significant interaction between time and sex. The probability of death for each sex takes into account the variation in probability of death with age.

Figure 6.

Effect modification of time (year) by age. Probability of death plotted against time stratified by age. The nonparallel nature of the plots is consistent with a statistically significant interaction between time and age. The probability of death within each age category takes into account the variation in probability of death with sex.