Non-index hospital re-admissions after hospitalisation with acute myocardial infarction and geographic remoteness, New South Wales, 2005–2020: a retrospective cohort study

Objectives

To examine the frequency of re-admissions to non-index hospitals (hospitals other than the initial discharging hospital) within 30 days of admission with acute myocardial infarction in New South Wales; to examine the relationship between non-index hospital re-admissions and 30-day mortality.

Study design

Retrospective cohort study; analysis of hospital admissions (Admitted Patient Data Collection) and mortality data (Registry of Births, Deaths and Marriages).

Setting, participants

Adults admitted to NSW hospitals with acute myocardial infarction re-admitted to any hospital within 30 days of discharge from the initial hospitalisation, 1 January 2005 – 31 December 2020.

Main outcome measures

Proportion of re-admissions within 30 days of discharge to non-index hospitals, and associations of non-index hospital re-admissions with demographic and initial hospitalisation characteristics and with 30-day and 12-month mortality, each by residential remoteness category.

Results

Of 168 097 people with acute myocardial infarction discharged alive, 28 309 (16.8%) were re-admitted to hospital within 30 days of discharge, including 11 986 to non-index hospitals (42.3%); the proportion was larger for people from regional or remote areas (50.1%) than for people from major cities (38.3%). The odds of non-index hospital re-admission were higher for people with ST-elevation myocardial infarction, for people whose index admissions were to private hospitals, who were transferred between hospitals or had undergone revascularisation during the initial admission, were under 65 years of age, or had private health insurance; the influence of these factors was generally larger for people from regional or remote areas than for those from large cities. After adjustment for potential confounders, non-index hospital re-admission did not influence mortality among people from major cities (30-day: adjusted odds ratio [aOR], 1.09; 95% confidence interval [CI], 0.99–1.20; 12-month: aOR, 0.98, 95% CI, 0.93–1.03), but was associated with reduced mortality for people from regional or remote areas (30-day: aOR, 0.81; 95% CI, 0.70–0.95; 12-month: aOR, 0.88; 95% CI, 0.81–0.96).

Conclusions

The geographically dispersed Australian population and the mixed public and private provision of specialist services means that re-admission to a non-index hospital can be unavoidable for people with acute myocardial infarction who are initially transferred to specialised facilities. Non-index hospital re-admission is associated with better mortality outcomes for people from regional or remote areas.