title: Preoperative Laboratory Investigations: Rates and Variability Prior to Low-risk Surgical Procedures.
abstract: BACKGROUND
  Increasing attention has been focused on low-value healthcare services. Through Choosing Wisely campaigns, routine laboratory testing before low-risk surgery has been discouraged in the absence of clinical indications. The authors investigated rates, determinants, and institutional variation in laboratory testing before low-risk procedures.
  
  
  METHODS
  Patients who underwent ophthalmologic surgeries or predefined low-risk surgeries in Ontario, Canada, between April 1, 2008, and March 31, 2013, were identified from population-based administrative databases. Preoperative blood work was defined as a complete blood count, prothrombin time, partial thromboplastin, or basic metabolic panel within 60 days before an index procedure. Adjusted associations between patient and institutional factors and preoperative testing were assessed with hierarchical multivariable logistic regression. Institutional variation was characterized using the median odds ratio.
  
  
  RESULTS
  The cohort included 906,902 patients who underwent 1,330,466 procedures (57.1% ophthalmologic and 42.9% low-risk surgery) at 119 institutions. Preoperative blood work preceded 400,058 (30.1%) procedures. The unadjusted institutional rate of preoperative blood work varied widely (0.0 to 98.1%). In regression modeling, significant predictors of preoperative testing included atrial fibrillation (adjusted odds ratio [AOR], 2.58; 95% CI, 2.51 to 2.66), preoperative medical consultation (AOR, 1.68; 95% CI, 1.65 to 1.71), previous mitral valve replacement (AOR, 2.33; 95% CI, 2.10 to 2.58), and liver disease (AOR, 1.69; 95% CI, 1.55 to 1.84). The median odds ratio for interinstitutional variation was 2.43.
  
  
  CONCLUSIONS
  Results of this study suggest that testing is associated with a range of clinical covariates. However, an association was similarly identified with preoperative consultation, and significant variation between institutions exists across the jurisdiction.
authors.affiliation: From the Department of Anesthesia and Pain Management, Toronto Western Hospital, Toronto, Ontario, Canada (K.R.K.); Department of Anesthesia, Women's College Hospital, Toronto, Ontario, Canada (K.R.K.); Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada (D.N.W.); Department of Anesthesia and Pain Management, Toronto General Hospital, Toronto, Ontario, Canada (D.N.W.); Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada (D.N.W., J.V.T., J.T., M.J.S., R.S.B.); Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (D.N.W., R.N., J.V.T., M.J.S., R.S.B.); Institute for Health System Solutions, Women's College Hospital, Toronto, Ontario, Canada (C.P., R.S.B.); Department of Medicine, University of Toronto, Toronto, Ontario, Canada (J.V.T., M.J.S., W.L., R.S.B.); Division of Cardiology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (J.V.T.); Department of Health Policy and Management, Harvard School of Public Health, Boston, Massachusetts (A.S.B.); Health Quality Ontario, Toronto, Ontario, Canada (J.T.); Department of Family and Community Medicine, University of Toronto, Toronto, Ontario, Canada (J.T.); Department of Emergency Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (M.J.S.); and Department of Cardiology, Women's College Hospital, Toronto, Ontario, Canada (R.S.B.).
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Kirkham
authors.forename: Duminda N
authors.initials: DN
authors.lastname: Wijeysundera
authors.forename: Ciara
authors.initials: C
authors.lastname: Pendrith
authors.forename: Ryan
authors.initials: R
authors.lastname: Ng
authors.forename: Jack V
authors.initials: JV
authors.lastname: Tu
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Boozary
authors.forename: Joshua
authors.initials: J
authors.lastname: Tepper
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Schull
authors.forename: Wendy
authors.initials: W
authors.lastname: Levinson
authors.forename: R Sacha
authors.initials: RS
authors.lastname: Bhatia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019411:Clinical Laboratory Techniques / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D009864:Ontario; D011300:Preoperative Care / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors; D013514:Surgical Procedures, Operative; D055815:Young Adult