Searching for inaccuracy in clinical laboratory testing using Medicare data. Evidence for prothrombin time
Mennemeyer, S.T.; Winkelman, J.W.
JAMA 269(8): 1030-1033
1993
ISSN/ISBN: 0098-7484 PMID: 8369028 Document Number: 407027
Objective: To determine if the occurrence of health outcomes following clinical laboratory testing can be used to identify types of laboratories that may be having higher than expected error rates. Design: Retrospective analysis of Medicare Part B outpatient claims, Part A hospitalization bills, and death records using a case-control study. Setting: Medicare records from six carrier territories were sampled during the period 1985 through 1987. Patients: A total of 14 755 Medicare patients receiving a prothrombin time test in either a physician office laboratory or a commercial laboratory. Outcome measures: Occurrence of a hospitalization for stroke or acute myocardial infarction, death, or no adverse outcome within 6 days of a prothrombin time. Results: In physician office laboratories where prothrombin time test voluem is below 40 per month, the odds that a tested patient will experience a stroke or an acute myocardial infarction are up to 1.96 and 3.43 times greater, respectively, than for a similar patient tested in a commercial laboratory. Switching from one laboratory to another between successive prothrombin time tests increased the odds of a stroke or an acute myocardial infarction by 1.57 and 1.32, respectively. Patients in two states with strong laboratory regulatory programs had fewer adverse outcomes. Conclusion: Examining patient outcomes subsequent to clinical laboratory testing may be a useful tool for clinical laboratory quality assurance.