Table 1 .
Characteristics of the included studies
| First author | Country | Year | Type | Patients, n (HT/BN) | Extent of surgery | Surgery of TT (HT/BN) | Transient RLN palsy (HT/BN) | Permanent RLN palsy (HT/BN) | THC (HT/BN) | PHP (HT/BN) | Definition | Quality score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wagner16 | Switzerland | 1994 | CC | 21/73 | I | NA | 0/1 | 1/0 | NA | NA | a | 5 |
| Shih9 | US | 2008 | C | 25/316 | II | 17/162 | 1/0 | 0/0 | 8/77 | 0/0 | a.b | 7 |
| Ebrahimi32 | Australia | 2009 | C | 93/312 | II | 93/312 | NA | NA | 3/18 | 0/3 | b | 6 |
| Pradeep23 | India | 2011 | CC | 33/236 | II | 24/117 | 0/0 | 0/0 | 3/10 | 0/0 | a | 5 |
| Enomoto22 | Japan | 2014 | CC | 20/375 | II | NA | 1/23 | 0/0 | NA | NA | a | 5 |
| Nawrot20 | Poland | 2014 | CC | 10/243 | I | NA | NA | NA | NA | 0/18 | d | 6 |
| Gupta25 | India | 2015 | P | 4/62 | II | 4/62 | NA | NA | 2/14 | NA | b | 6 |
| Thomusch26 | Germany Poland Czech Austria | 2018 | P | 1268/16467 | II | 844/8890 | 44/642 | 11/132 | 194/2124 | 14/148 | a.b | 8 |
| Ravikumar21 | India | 2018 | CC | 108/452 | II | 108/452 | 12/34 | 5/8 | 48/112 | 4/10 | a.c | 7 |
BN = benign nodule; C = cohort; CC = case-control; HT = Hashimoto’s thyroiditis; NA = data not available; P = prospective; RLN = recurrent laryngeal nerve
I = including subtotal, total thyroidectomy together with lobectomy or completion thyroidectomy; II = all total thyroidectomy
a = preoperative and postoperative laryngoscopy; b = THC is defined by a serum calcium <8–8.5mg/dl for less than 6 months, and permanent hypoparathyroidism (PHP) is defined by calcium and/or vitamin D requirements for longer than 6 months; c = THC is defined by a parathyroid hormone (PTH) level <10pg/ml within 24 h of the operation that eventually increases to >10pg/ml within 6 months or permanent hypocalcaemia longer than 6 months; d = PHP is defined by calcium and/or vitamin D requirements for longer than 12 months