title: What proportion of common diagnostic tests appear redundant?
abstract: OBJECTIVE
  To identify ancillary tests for which there are criteria defining the earliest interval at which a repeat test might be indicated, to determine how often each test is repeated earlier than these intervals and, if repeated, provides useful information.
  
  
  METHODS
  We performed a retrospective cohort study of 6,007 adults discharged from a large teaching hospital during a 3-month period in 1991. We measured the proportion of commonly performed diagnostic tests that were redundant, and their associated charges.
  
  
  RESULTS
  Of the 6,007 patients discharged, 5,289 (88%) had at least one of 12 target tests performed. Overall, 78,798 of the target tests were performed during the study period, of which 22,237 (28%) were repeated earlier than test-specific predefined intervals. This percentage varied substantially by test (range, 2% to 62%). To assess how many early repeats were justified, we performed chart reviews in a random sample stratified by test. For two tests, nearly all the initial results in the sample were abnormal, and all repeats were considered justified. Of early repeats following a normal initial result for the remaining 10 tests, chart review found no clinical indication for 92%, and a weighted mean of 40% appeared redundant. Overall, 8.6% of these 10 tests appeared redundant; if these were not performed, the annual charge reductions would be $930,000 at our hospital, although the impact on costs would be much smaller.
  
  
  CONCLUSIONS
  For some tests, an important proportion are repeated too early to provide useful clinical information. Most such tests might be eliminated using computerized reminder systems.
authors.affiliation: Center for Applied Medical Information Systems, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Bates
authors.forename: D L
authors.initials: DL
authors.lastname: Boyle
authors.forename: E
authors.initials: E
authors.lastname: Rittenberg
authors.forename: G J
authors.initials: GJ
authors.lastname: Kuperman
authors.forename: N
authors.initials: N
authors.lastname: Ma'Luf
authors.forename: V
authors.initials: V
authors.lastname: Menkin
authors.forename: J W
authors.initials: JW
authors.lastname: Winkelman
authors.forename: M J
authors.initials: MJ
authors.lastname: Tanasijevic
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D003955:Diagnostic Tests, Routine / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D011237:Predictive Value of Tests; D011787:Quality of Health Care; D012189:Retrospective Studies; D014481:United States