Block & replace regime versus titration regime of antithyroid drugs for the treatment of Graves' disease: a retrospective observational study

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Vaidya, Bijay
Wright, Ailsa
Shuttleworth, Joanna
Donohoe, Mollie
Warren, Roderick
Brooke, Antonia
Gericke, Christian A.
Ukoumunne, Obiaha C.
Clinical endocrinology
Journal Article
Research Support, Non-U.S. Gov't
CONTEXT: 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.
Clin Endocrinol (Oxf). 2014 Oct;81(4):610-3.