title: Block & replace regime versus titration regime of antithyroid drugs for the treatment of Graves' disease: a retrospective observational study.
abstract: BACKGROUND
  Two widely used antithyroid drug (ATD) regimes for Graves' disease (GD) include the 'block & replace' (B&R) regime (a fixed high-dose of ATD combined with levothyroxine) and the 'titration' regime (a titrating dose of ATD). Anecdotally, it is believed that B&R is less prone to fluctuating thyroid function.
  
  
  OBJECTIVE
  To study whether, in routine clinical practice, the B&R regime, compared with the titration regime, is associated with more stable thyroid function.
  
  
  METHODS
  We retrospectively analysed case-records for 450 patients treated with ATDs for GD at a secondary care hospital. Exclusion criteria included treatment with ATDs for <6 months, thyrotoxicosis due to other causes, treatment with radioiodine or thyroidectomy and pregnancy.
  
  
  RESULTS
  Two hundred and twenty three patients were treated with the B&R regime ('B&R group'), 149 with the titration regime ('titration group') and 78 with both regimes. The number of thyroid function tests (TFTs) performed per year (mean(SD): 3·2(1·2) vs 3·4(1·5); adjusted mean difference = -0·4; 95% CI: -0·7 to -0·1; and P = 0·008) and the number of hospital clinic visits per year (mean (SD): 2·9 (1·0) vs 3·2 (1·3); adjusted mean difference = -0·4; 95% CI: -0·7 to -0·2; and P = 0·002) were lower in the B&R group than the titration group. The number of abnormal TFT results per year was similar in the two groups (mean(SD): 1·8(1·3) vs 1·8(1·4); adjusted mean difference = 0·05; 95%CI: -0·3 to 0·4; and P = 0·74).
  
  
  CONCLUSIONS
  In this retrospective study, there was little evidence that patients under B&R have more stable thyroid function. Further data from prospective studies, however, are needed to confirm this finding.
authors.affiliation: Department of Endocrinology, Royal Devon & Exeter Hospital, Exeter, UK; NIHR CLAHRC South West Peninsula (PenCLAHRC), University of Exeter Medical School, Exeter, UK.
authors.forename: Bijay
authors.initials: B
authors.lastname: Vaidya
authors.forename: Ailsa
authors.initials: A
authors.lastname: Wright
authors.forename: Joanna
authors.initials: J
authors.lastname: Shuttleworth
authors.forename: Mollie
authors.initials: M
authors.lastname: Donohoe
authors.forename: Roderick
authors.initials: R
authors.lastname: Warren
authors.forename: Antonia
authors.initials: A
authors.lastname: Brooke
authors.forename: Christian A
authors.initials: CA
authors.lastname: Gericke
authors.forename: Obioha C
authors.initials: OC
authors.lastname: Ukoumunne
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D013956:Antithyroid Agents / Q000627:therapeutic use*; D005260:Female; D006111:Graves Disease / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D013956:Antithyroid Agents