Diabetes-associated short-term mortality after first-onset acute myocardial infarction: age- and residence-specific patterns in an underserved region.

backgroundUrban-rural disparities in acute myocardial infarction (AMI) outcomes are well documented, and may be related to delayed emergency access and uneven service distribution. However, the ways in which structural barriers may amplify vulnerabilities associated with age at AMI onset and diabetes in underserved settings remain understudied, despite their importance for equity-oriented emergency care planning.

methodsWe conducted a 16-year retrospective cohort study of 1,591 first-onset AMI patients who were identified through the sole AMI-capable medical centre in Eastern Taiwan. The primary endpoint was overall short-term mortality (30-day mortality), which was further categorized into pre-hospital and post-arrival 30-day mortality. The interaction between age and diabetes was first examined to assess differential short-term mortality risks. To contextualize these effects within structural healthcare disparities, patients were further stratified by urban or rural residence. Adjusted odds ratios were estimated across four strata defined by age group (younger vs. older) and residence (urban vs. rural) to assess how structural disparities relate to mortality patterns associated with age at AMI onset and diabetes.

resultsShort-term mortality rose stepwise across groups (young non-diabetes 1.9%, young diabetes 8.2%, old non-diabetes 10.7%, old diabetes 17.9%). Diabetes was associated with higher short-term mortality in both age groups, with a stronger association among younger patients (aOR: 3.83 vs. 1.60; p-for-interaction = 0.045). Among younger patients, diabetes was particularly associated with pre-hospital mortality (aOR: 6.32, 95% CI 1.21-32.88), suggesting a greater vulnerability during the early emergency phase. In residence-stratified analyses, the association between diabetes and short-term mortality was most pronounced among younger rural patients (aOR: 4.24, 95% CI 1.21-14.84). Exploratory subgroup analyses suggested longer onset-to-presentation intervals in some rural subgroups; however, these findings were based on limited event counts and should be interpreted cautiously.

conclusionsDiabetes was associated with higher short-term mortality after first-onset AMI, particularly among younger patients and those living in rural areas. These findings identify a high-risk subgroup in an underserved region. Future studies incorporating direct systems-of-care measures are needed to determine whether geographic and emergency-care access factors contribute to this diabetes-related vulnerability.