Acute coronary syndrome registry enrolment status: differences in patient characteristics and outcomes and implications for registry data use (ANZACS-QI 36).

AIMS: Clinical registry-derived data are widely used to represent patient populations. In New Zealand (NZ), a national registry-the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) registry-aims to include all patients undergoing coronary angiography; other acute coronary syndrome (ACS) patients are also registered but without complete capture. This study compares national hospitalization data of all first-time ACS admissions in NZ with patients in the ANZACS-QI registry, to investigate the use of clinical registry-derived data in research and in assessing clinical care. METHODS AND RESULTS: Patients admitted with first-time ACS in the NZ National Hospitalisation Dataset between 1 January 2015 and 31 December 2016 were included. Clinical characteristics and time to 12-month clinical outcomes were compared between patients captured and not-captured in the registry. A total of 16 569 patients were admitted with first-time ACS, median age 69 years, 61% male; 60% (n = 9918) were enrolled in ANZACS-QI. Registry-captured patients were younger, more often male, and with a lower comorbidity burden than non-captured patients. Overall, 16% patients died within 12 months, 15% experienced a non-fatal cardiovascular (CV) readmission, and 28% either died or were readmitted. Patients not captured in the registry were more than twice as likely to have experienced death or a non-fatal CV readmission within 12 months as captured patients. CONCLUSIONS: First-time ACS patients captured in the ANZACS-QI registry had very different clinical characteristics and outcomes than those not captured. Cardiovascular registry-derived data are dependent on registry design and may not be representative of the wider patient population; this must be considered when using registry-derived data.