Am Heart J. 2021 Jan 15:S0002-8703(21)00012-0. doi: 10.1016/j.ahj.2021.01.008. Online ahead of print.
BACKGROUND: CODE-MI is a pan-Canadian, multi-centre, stepped-wedge, cluster randomized trial that evaluates the impact of using the female-specific 99th percentile threshold for high-sensitivity cardiac troponin (hs-cTn) on the diagnosis, treatment and outcomes of women presenting to the emergency department (ED) with symptoms suggestive for myocardial ischemia. A feasibility study was conducted to estimate the number of eligible patients, the rate of the study's primary outcome under control conditions, and the statistical power to detect a clinically important difference in the primary outcome.
METHODS: Using linked administrative data from 11 hospitals in Ontario, Canada, from October 2014 to September 2017, the following estimates were obtained: number of women presenting to the ED with symptoms suggestive of myocardial ischemia and a 24-hour peak hs-cTn value within the female-specific and overall thresholds (i.e. primary cohort); the rate of the 1-year composite outcome of all-cause mortality, re-admission for non-fatal myocardial infarction, incident heart failure, or emergent/urgent coronary revascularization. Study power was evaluated via simulations.
RESULTS: Overall, 2,073,849 ED visits were assessed. Among women, chest pain (with or without cardiac features) and shortness of breath were the most common complaints associated with a diagnosis of acute coronary syndrome. An estimated 7.7% of women with these complaints are eligible for inclusion in the primary cohort. The rate of the 1-year outcome in the primary cohort varied significantly across hospitals with a median rate of 12.2% (95%CI: 7.9%-17.7%). With 30 hospitals, randomized at 5-month intervals in 5 steps, approximately 19,600 women are expected to be included in CODE-MI, resulting in >82% power to detect a 20% decrease in the odds of the primary outcome at a 0.05 significance level.
CONCLUSIONS: This feasibility study greatly enhanced the design of CODE-MI, allowed accurate evaluation of the study power, and demonstrated the strength of using linked administrative health data to guide the design of pragmatic clinical trials.