Rate of recurrent hyperthyroidism	Permanent recurrent laryngeal nerve palsy	Permanent hypocalcaemia/hypoparathyroidism	Regression of Graves' ophthalmopathy	Health‐related quality of life	Socioeconomic effects	Severe/serious adverse events
Barczynski 2012	Laboratory tests included measurement of serum free tri‐iodothyronine (fT3; reference range 0.22 to 6.78 pmol/L), free thyroxine (fT4; reference range 12 to 30 pmol/L) and thyroid‐stimulating hormone (TSH, thyrotropin; reference range 0.4 to 4.2 units/L). A serum thyrotropin binding inhibitory immunoglobulin (TBII) level > 1.5 units/L was defined as positive	Vocal cord paresis for more than 12 months after the operation was regarded as permanent Indirect laryngoscopy was performed before surgery	Persistent hypocalcaemia with serum PTH level below 10 ng/L for more than 12 months	The following definitions were used: a change in TES and/or CAS of fewer than 2 points from the preoperative baseline value was regarded as ‘no change’, an increase in TES and/or CAS of 2 points or more was regarded as‘progression’, and a decrease in TES and/or CAS of 2 points or more was regarded as ‘improvement’ Assessed by blinded ophthalmologist Measured at yearly intervals for 5 years postop	N/I	N/I	One death reported (due to a myocardial infarction 3 years after surgery)
Chi 2005	Suppressed TSH (human TSH radioimmunoassay kit measured between 3‐26.4 months after surgery	RLN palsy defined as permanent if longer than 6 months Based on independent ENT specialist assessment and patient report	Permanent hypocalcaemia if longer than 6 months postop.. Assessed by external laboratory	N/I	N/I	N/I	N/I
Jarhult 2005	N/I	RLN palsy considered permanent if persisting > 9 months (unclear whether laryngoscopy was performed)	Persistent hypocalcaemia > 9 months	1. Improvement in ophthalmological score (based on author experience, not validated) 2. Improvment in objective and subjective evaluation of eye symptoms by patient and ophthalmologist	N/I	N/I	N/I
Witte 2000	N/I	RLN palsy defined as permanent if longer than 6 months Assessed by independent ENT specialist	Permanent hypocalcaemia if longer than 6 months postop.. Assessed by external laboratory	GO measured from > 18‐58 months postop using standardised scale Both patient reported and ophthalmology assessment scores are reported	N/I	N/I	N/I
Muller 2001	Biochemical tests of TSH, fT3 and fT4 with reference levels as per local laboratory. Suppressed TSH and elevated fT3/fT4 was taken to be evidence of hyperthyroidism (measured at 6 years)	Recurrent laryngeal nerve palsy defined by impaired vocal cord movement seen on laryngoscopy (preop and postop laryngoscopy routine). Considered permanent if persisting more than 1 year	Hypocalcaemia persisting more than 1 year was considered to be permanent	Surgical team/physician assessment Unclear what scale was used or whether an ophthalmologist was involved Outcome measured at 6 years	N/I	N/I	No deaths
CAS: clinical activity score; ENT: ear, nose & throat; fT3: free tri‐iodothyronine; fT4: free thyroxine; GO: Graves' ophthalmopathy; N/I: not investigated; PTH: parathyroid hormone; RLN: recurrent laryngeal nerve; TES: total eye score; TT: total thyroidectomy; TSH: thyroid‐stimulating hormone