Prothrombin Time and Activated Partial Thromboplastin Time Testing: A Comparative Effectiveness Study in a Million-Patient Sample.
BACKGROUND
A substantial fraction of all American healthcare expenditures are potentially wasted, and practices that are not evidence-based could contribute to such waste. We sought to characterize whether Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT) tests of preoperative patients are used in a way unsupported by evidence and potentially wasteful.


RESULTS
We evaluated prospectively-collected patient data from 19 major teaching hospitals and 8 hospital-affiliated surgical centers in 7 states (Delaware, Florida, Maryland, Massachusetts, New Jersey, New York, Pennsylvania) and the District of Columbia. A total of 1,053,472 consecutive patients represented every patient admitted for elective surgery from 2009 to 2012 at all 27 settings. A subset of 682,049 patients (64.7%) had one or both tests done and history and physical (H&P) records available for analysis. Unnecessary tests for bleeding risk were defined as: PT tests done on patients with no history of abnormal bleeding, warfarin therapy, vitamin K-dependent clotting factor deficiency, or liver disease; or aPTT tests done on patients with no history of heparin treatment, hemophilia, lupus anticoagulant antibodies, or von Willebrand disease. We assessed the proportion of patients who received PT or aPTT tests who lacked evidence-based reasons for testing.


CONCLUSIONS
This study sought to bring the availability of big data together with applied comparative effectiveness research. Among preoperative patients, 26.2% received PT tests, and 94.3% of tests were unnecessary, given the absence of findings on H&P. Similarly, 23.3% of preoperative patients received aPTT tests, of which 99.9% were unnecessary. Among patients with no H&P findings suggestive of bleeding risk, 6.6% of PT tests and 7.1% of aPTT tests were either a false positive or a true positive (i.e. indicative of a previously-undiagnosed potential bleeding risk). Both PT and aPTT, designed as diagnostic tests, are apparently used as screening tests. Use of unnecessary screening tests raises concerns for the costs of such testing and the consequences of false positive results.
Department of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, New York, United States of America; MMF Systems, Inc., New York, New York, United States of America.
Manu N
MN
Capoor
Department of Anesthesia, The Johns Hopkins Hospital, Baltimore, Maryland, United States of America.
Jerry L
JL
Stonemetz
MMF Systems, Inc., New York, New York, United States of America.
John C
JC
Baird
MMF Systems, Inc., New York, New York, United States of America.
Fahad S
FS
Ahmed
Department of Anesthesia, Englewood Hospital and Medical Center, Englewood, New Jersey, United States of America.
Ahsan
A
Awan
Ludwig-Maximilian University of Munich, Munich, Germany.
Christof
C
Birkenmaier
Westchester Medical Center/New York Medical College, Valhalla, New York, United States of America.
Mario A
MA
Inchiosa
Hospital for Special Surgery, New York, New York, United States of America.
Steven K
SK
Magid
Westchester Medical Center/New York Medical College, Valhalla, New York, United States of America.
Kathryn
K
McGoldrick
Department of Surgery, North Shore University Hospital, Manhasset, New York, United States of America.
Ernesto
E
Molmenti
Department of Anesthesia, Englewood Hospital and Medical Center, Englewood, New Jersey, United States of America.
Sajjad
S
Naqvi
Department of Anesthesia, Washington Hospital Center, Washington, DC, United States of America.
Stephen D
SD
Parker
Westchester Medical Center/New York Medical College, Valhalla, New York, United States of America.
S M
SM
Pothula
Department of Anesthesia, Englewood Hospital and Medical Center, Englewood, New Jersey, United States of America.
Aryeh
A
Shander
MMF Systems, Inc., New York, New York, United States of America.
R Grant
RG
Steen
Hospital for Special Surgery, New York, New York, United States of America.
Michael K
MK
Urban
Atlantic Health System, Morristown, New Jersey, United States of America.
Judith
J
Wall
Department of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, New York, United States of America.
Vincent A
VA
Fischetti
D000328:Adult; D000368:Aged; D055317:Evidence-Based Practice / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011300:Preoperative Care / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D011517:Prothrombin Time; D014481:United States; D019564:Unnecessary Procedures; D055815:Young Adult