Differential effect of socioeconomic status on rates of invasive coronary procedures across the public and private sectors in Queensland, Australia

Abstract

We used computerised discharge abstracts to conduct a population-based cohort study of the 3531 patients admitted to Queensland hospitals for acute myocardial infarction (AMI) during 1998. AMI patients were identified using the ICD9-CM code 410.x1: first episode of care for a newly diagnosed myocardial infarction. Follow up was for one year and used probabilistic matching based on Medicare number, date of birth, sex, country of birth and address of usual residence. We applied two exclusion criteria: (1) age younger than 30 years or older than 89 years, (2) discharge status of alive and length of stay less than four days. These criteria have been shown in other studies (based on computerised discharge abstracts) to be optimal for reducing the number of false positive diagnoses of AMI.3