P141| Volume 37, ISSUE 10, SUPPLEMENT , S84, October 2021

# EFFECTIVENESS AND FINANCIAL IMPACT OF A PROVINCIAL POLICY ELIMINATING ROUTINE USE OF CREATINE KINASE TESTING FOR WORK-UP OF SUSPECTED ACUTE CORONARY SYNDROME IN THE EMERGENCY DEPARTMENT

### BACKGROUND

Creatine kinase (CK) has long been a cornerstone in the diagnosis of ACS. However, it has been demonstrated that CK is not useful in the era of high-sensitivity troponin (hsTn) assays. In August 2020, a joint Choosing Wisely Manitoba® and Shared Health Manitoba practice change statement eliminating the routine use of CK for diagnosis of ACS was adopted. The policy was a written document highlighting that CK was an unnecessary test for ACS screening, and was distributed broadly to all health regions in Manitoba. We conducted a study to determine whether this policy change successfully reduced CK testing in emergency departments (EDs) across Manitoba, and the potential cost savings achieved.

### METHODS AND RESULTS

A retrospective study was conducted using the Diagnostic Services Manitoba Laboratory Information Management System database. The total number of CK and hsTn tests ordered in all EDs across Manitoba were collected. As surrogates for total ED presentations and CK ordered for non-ACS indications, total number of CBCs and myoglobin tests were obtained. Data was collected 5-months (March 1 to July 31, 2020) prior to the policy change and 5-months (September 1 to January 31, 2021) following the policy change, which occurred in August 2020. Hypothesis testing was done with Chi square testing, with significance defined as p < 0.05. Prior to the policy change 88792 CBCs, 33079 hsTn, 2826 Myoglobin, and 20035 CK tests were ordered among all provincial EDs during the study period. Urban teaching hospitals ordered CK concurrently with hsTn 15.8% of the time, while it was ordered concurrently 33.1% of the time in peripheral EDs. Following the policy change, there was no difference in CBCs, hsTn, or myoglobins ordered, but there was a significant reduction in CK tests ordered (20035 vs 11840, p < 0.0001). There was a 54% relative reduction in CK use across the province following the policy change, (22.6% vs 12.2%; p < 0.0001). Individually, urban teaching hospitals decreased CK testing to 10.2%, while peripheral EDs decreased their CK testing to 15.3%. Based on a cost of $4/test, the 54% relative reduction in CK testing was estimated to result in a >$31000 in cost-savings over the course of a year.

### CONCLUSION

The results of this study suggest that passive intervention through public health policy change is effective in reducing unnecessary testing across an entire health region.