Muller 2001.

Methods	Type of study: randomised controlled clinical trial Allocation: 1:1 Intervention model: parallel group superiority design Masking: no blinding of patients or personnel Primary purpose: treatment of Graves' disease
Participants	Condition: Graves' disease Enrolment: 152 in total Inclusion criteria: 1. Diagnosis of Graves disease 2. Completed six years follow‐up 3. Euthyroidism at time of operation Exclusion criteria: not specified Diagnostic criteria: hyperthyroidism with endocrine ophthalmopathy or TSH‐R antibodies and characteristics of Graves' disease on ultrasound scan
Interventions	Number of study centres: 1 Treatment before study: preoperative treatment with antithyroid medications if hyperthyroid Titration period: none Intervention(s): 1. Bilateral subtotal thyroidectomy with 3 mL of remaining tissue Comparator(s): 2. Ipsilateral lobectomy and contralateral subtotal resection with 3 mL thyroid remnant per side (6 mL total)
Outcomes	Primary outcome(s): 1. Recurrent hyperthyroidism Secondary outcome(s): 2. Permanent hypoparathyroidism 3. Recurrent laryngeal nerve palsy 4. Wound complications (seroma, infection, haematoma) 5. Progression of Graves' Ophthalmopathy Other outcome(s): ‐
Study details	Run‐in period: none Study terminated before regular end (for benefit/because of adverse events): no Study start date: 1988 Study completion date: 1992
Publication details	Language of publication: English Funding: not stated Publication status: peer‐reviewed journal, full article
Stated aim for study	In this prospective randomised study, the two methods (bilateral subtotal resection and the Dunhill operation) are evaluated with respect to their operative and postoperative complications and their long term results [in treatment of Grave's disease]
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote from publication: "We examined 152 patients... in a prospective randomised study" Comment: the study is prospectively randomised although randomisation techniques not described
Allocation concealment (selection bias)	Unclear risk	Comment: not clearly stated whether allocation concealment took place
Blinding of participants and personnel (performance bias) Objective outcomes	High risk	Quote from publication: "The surgeons were specialised surgeons or were directly supervised by specialised surgeons" Comment: not stated whether surgeons were blinded to group allocation
Blinding of participants and personnel (performance bias) Subjective outcomes	High risk	Comment: not stated whether patients were blinded to group allocation
Blinding of outcome assessment (detection bias) Objective outcomes	Unclear risk	Quote from publication: "Following surgery, patients were started on a thyroxine replacement regimen with iodine and levothyroxine, and the regimen was later adjusted according to their free T3, T4 and TSH levels. All patients had a repeat ... measurement of their plasma calcium" Comment: evaluation of TRAb, thyroid function and calcium: laboratory standard tests
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Quote form publication: "the 6 year follow up period ended with a questionnaire sent to the physician currently treating the patient" Comment: unclear whether physician completing follow‐up questionnaire was blinded to intervention; not clear who assessed eye involvement
Incomplete outcome data (attrition bias) Objective outcomes	High risk	Quote from publication: "after 6 years, 99 patients returned the questionnaire" Comment: outcomes only reported in 99/152 (63%) participants
Incomplete outcome data (attrition bias) Subjective outcomes	High risk	Quote from publication: "after 6 years, 99 patients returned the questionnaire" Comment: outcomes only reported in 99/152 (63%) participants
Selective reporting (reporting bias)	Low risk	Comment: outcomes reported appear to be standard for studies addressing this type of question
Other bias	Low risk	Comment: no other risk of bias detected