Criteria for Routine Laboratory Blood Tests in Patients Hospitalized in Cardiology Departments

The proportion of laboratory tests ordered in cardiology departments without clinical utility is unclear. The objective of this study was to determine if criteria limiting testing can safely reduce admission and follow-up testing. We reviewed the charts of 471 consecutive patients admitted to the cardiology department at a regional hospital from January 2019 to June 2019. We prospectively set appropriate criteria for routine admission and follow-up testing. Commonly ordered tests and parameters considered not to be indicated either on admission or on follow-up included C-reactive protein, liver function tests, lactate dehydrogenase, creatine phosphokinase, calcium, blood urea nitrogen, uric acid, cholesterol, Hemoglobin A1c, and prothrombin times (except for patients treated with warfarin). Admission tests considered appropriate included electrolytes, glucose, creatinine, and complete blood counts. Follow-up testing was indicated only if test results were outside the reference ranges. Troponin tests were only indicated if needed to determine the need for a coronary angiogram. The outcome variables were the proportion of indicated tests and whether tests outside the criteria led to changes in acute care that positively affected the patient's hospital care. In the 471 patients, there were 18,061 tests ordered (not including troponin), and 14,427 (79.9%) were not indicated; this led to 46 (0.3%) changes in medical care, which did not affect the patients' clinical course. There were 47.8% (364/761) troponin tests that were not indicated and did not change patient care. Our study suggests that interventions in cardiology departments such as ours could safely reduce troponin testing by nearly 50% and other laboratory tests by around 80%. These results need to be confirmed in other settings and in interventional studies.