title: Quality assurance study of cardiac isoenzyme utilization in a large teaching hospital.
abstract: Guidelines for diagnosis of acute myocardial infarction recommend that, if acute myocardial infarction is suspected, creatine kinase (CK)-MB levels should be measured on admission and again at 12 and 24 hours. In light of these recommendations, we conducted a quality assurance study to determine whether utilization of CK-MB tests in our institution, a large, university-affiliated teaching hospital, was consistent with current guidelines. Also, several years ago, we had established a policy of cancelling lactate dehydrogenase isoenzyme orders if the request originated from an unauthorized location, unless it was approved by a laboratory staff. Since this policy led to a greater than 90% reduction in the requests for lactate dehydrogenase isoenzyme testing, an additional objective was to reevaluate this policy. Of 774 patients evaluated with CK-MB tests, 294 (38%) received only a single test. Of these single tests, 277 had normal results (CK-MB < 5%). For the remaining 17 patients, the single CK-MB test findings were abnormal (CK-MB > 5%) without follow-up testing. Only two CK-MB tests were ordered for 187 patients (24%). Three or more CK-MB tests were obtained in 293 cases (38%). When two or more CK-MB tests were ordered, the time interval between the first and second tests was inappropriately short in 70% and long in 24%. The recommended timing for the third CK-MB was followed in only 4% of cases. Review of 32 cancellations of lactate dehydrogenase isoenzyme tests disclosed that lactate dehydrogenase isoenzyme tests were requested when unnecessary in 26 cases. Despite published guidelines for use of CK-MB for acute myocardial infarction, physicians at our institution continue to use these tests inappropriately by ordering only single CK-MB tests or by ordering repetitions of CK-MB tests at excessively short or long intervals.
authors.affiliation: Department of Pathology, University of Southern California School of Medicine, Los Angeles.
authors.forename: S
authors.initials: S
authors.lastname: Saxena
authors.forename: D W
authors.initials: DW
authors.lastname: Anderson
authors.forename: R L
authors.initials: RL
authors.lastname: Kaufman
authors.forename: J A
authors.initials: JA
authors.lastname: Hannah
authors.forename: E T
authors.initials: ET
authors.lastname: Wong
mesh_terms: D004796:Clinical Enzyme Tests / Q000706:statistics & numerical data*; D003402:Creatine Kinase / Q000032:analysis*; D006784:Hospitals, Teaching; D006801:Humans; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D009203:Myocardial Infarction / Q000175:diagnosis*; D011446:Prospective Studies; D011785:Quality Assurance, Health Care; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase