title: Evaluation of thyroid test utilization through analysis of population-level data.
abstract: BACKGROUND
  Inappropriate laboratory test utilization can result in unnecessary patient testing and increased healthcare costs. While several thyroid function tests are available, thyroid-stimulating hormone (TSH) is recommended as the first-line test for investigating and monitoring thyroid dysfunction. We evaluate thyroid test utilization in Northern Alberta in terms of testing patterns, frequencies, and reflex cutpoints.
  
  
  METHODS
  This retrospective study analyzed thyroid test requests from January to December 2014. Each request was designated as appropriate or potentially inappropriate as per clinical practice guidelines and Choosing Wisely recommendations, and the frequencies of each testing pattern were calculated. Sub-analysis was performed to categorize testing patterns based on physician specialty. The number of test requests per patient was determined to assess the appropriateness of testing frequency. Receiver operating characteristic (ROC) curves were generated to define optimal TSH cutpoints for automatic reflex to FT4 testing.
  
  
  RESULTS
  Of 752,217 test requests, approximately 10% were potentially inappropriate in terms of testing patterns. Free thyroxine (FT4) and free triiodothyronine (FT3) requested with TSH accounted for 59% of all potentially inappropriate test requests, and 49% of requests from endocrinologists (ENDO) were potentially inappropriate, occurring most frequently among those with less experience. Excessive testing frequencies were observed in 869 patients, accounting for 9382 test requests. Adjustment of our TSH reflex cutpoint would significantly increase specificity for identifying a low FT4 without compromising sensitivity.
  
  
  CONCLUSIONS
  This study suggests that questionable testing patterns, excessive testing frequencies, and suboptimal reflexive testing cutpoints contribute to inappropriate thyroid test utilization.
authors.affiliation: .
authors.forename: Jasmine
authors.initials: J
authors.lastname: Gill
authors.affiliation: .
authors.forename: Vilte E
authors.initials: VE
authors.lastname: Barakauskas
authors.affiliation: .
authors.forename: Dylan
authors.initials: D
authors.lastname: Thomas
authors.affiliation: .
authors.forename: Karina
authors.initials: K
authors.lastname: Rodriguez-Capote
authors.affiliation: .
authors.forename: Trefor
authors.initials: T
authors.lastname: Higgins
authors.affiliation: .
authors.forename: Don
authors.initials: D
authors.lastname: Zhang
authors.affiliation: .
authors.forename: Amanda
authors.initials: A
authors.lastname: VanSpronsen
authors.affiliation: .
authors.forename: Oksana
authors.initials: O
authors.lastname: Babenko
authors.affiliation: .
authors.forename: Roberta
authors.initials: R
authors.lastname: Martindale
authors.affiliation: .
authors.forename: Mathew P
authors.initials: MP
authors.lastname: Estey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000032:analysis*; D055815:Young Adult
chemical_list: D013972:Thyrotropin
keywords: free T3; free T4; reflex algorithm; test utilization; thyroid; thyroid-stimulating hormone