Abstract 17072: Mortality Outcomes Following Inter-Hospital Transfer (IHT) for Acute Myocardial Infarction (AMI)
Background: IHT is common in AMI yet there are limited population studies evaluating its effect upon mortality.
Methods: All patients (n=40,028) with a principle ICD10 diagnosis of AMI (14,115 STEMI, 25,913 NSTEMI) admitted to 161 acute care hospitals in New South Wales, Australia from 2004-08, with linkage to the state death register for post-discharge mortality. The effect of IHT upon mortality was compared using a 1:1 propensity score matched (PSM) sample with matching based on 74 variables encompassing patient demographic characteristics, background history, acute complications at presentation and presenting hospital characteristics. Median follow-up was 3.5 years (range 1.5-5.5).
Results: 29,939 (74.8%) patients received care at the presenting hospital while 10,089 (25.2%) were transferred. Transferred patients were younger, had less pre-existing cardiac disease, fewer comorbidities and less acute complications at presentation. They were more likely to have an initial admission at a regional (33.3%vs21.2%, p<0.01) or non-angiography capable (73.6%vs37.9%, p<0.01) hospital and to undergo revascularisation by PCI or CABG (56.8%vs 26.5%, p<0.001). PSM sample consisted of 8427 matched pairs (n=16854) with excellent covariate balance. The PSM transferred patients had lower mortality at 30-days (HR 0.60, 95%CI 0.52-0.70), 1 year (HR 0.58, 95%CI 0.52-0.64) and at a median follow-up time of 3.5y (HR 0.65, 95%CI 0.61-0.70). Multiple subgroup analyses showed a persisting mortality benefit from IHT including in those aged <65y (HR 0.77, 95%CI 0.64-0.93) and when in-hospital deaths were excluded (HR 0.64,95%CI 0.59-0.70), suggesting survival bias due to early death is unlikely to explain the mortality benefit. After adjustment for the likelihood of receipt of revascularisation at index admission, the long term mortality of benefit of IHT was reduced but remained significant (HR 0.89, 95%CI 0.83-0.96). Inverse propensity score weighted analysis of IHT using the entire cohort (n=40028) indicated similar survival gains.
Conclusion: IHT is associated with a survival advantage which is present within 30 days following AMI and sustained long-term. Greater use of revascularisation by IHT only partially explains the observed survival gains of IHT.
- © 2012 by American Heart Association, Inc.