Table 3.

 Factors independently associated with occurrence of permanent complications after thyroid surgery (multivariate analysis)

Variable	Permanent complications (odds ratio (95% CI)
	Recurrent laryngeal nerve palsy				Hypoparathyroidism
	Unadjusted		Adjusted†		Unadjusted		Adjusted‡
Length of surgeon experience
<2 years	3.59 (0.98 to 13.10)		2.41 (0.69 to 8.36)		4.44 (1.15 to 17.10)		5.93 (1.28 to 27.39)
2-4 years	2.34 (0.64 to 8.53)		1.77 (0.55 to 5.69)		4.77 (1.33 to 17.16)		5.80 (1.34 to 25.10)
5-19 years	1.00		1.00		1.00		1.00
≥20 years	2.78 (0.83 to 9.32)		3.06 (1.07 to 8.80)		5.24 (1.50 to 18.34)		7.56 (1.79 to 31.99)
Surgical procedures performed by surgeon on same day (n)
<3 procedures	1.00		1.00		1.00		1.00
3-4 procedures	0.76 (0.42 to 1.37)		0.90 (0.46 to 1.79)		0.73 (0.45 to 1.20)		0.84 (0.49 to 1.46)
≥5 procedures	0.84 (0.33 to 2.12)		1.15 (0.42 to 3.20)		0.65 (0.26 to 1.58)		0.73 (0.26 to 2.05)
Type of surgical case
Routine	1.00		1.00		1.00		1.00
Complex*	1.24 (0.69 to 2.24)		1.56 (0.80 to 3.07)		1.58 (1.00 to 2.51)		1.51 (0.89 to 2.55)
Patient sex
Male	1.00		1.00		1.00		1.00
Female	2.25 (1.02 to 4.98)		2.74 (1.08 to 6.97)		2.15 (1.10 to 4.22)		1.98 (0.96 to 4.06)
Patient age
By 10 year increase	1.00 (0.98 to 1.02)		1.02 (0.83 to 1.25)		0.98 (0.97 to 0.99)		0.84 (0.71 to 0.99)
Patient body mass index
By 5 point increase	1.04 (0.99 to 1.09)		1.21 (0.93 to 1.57)		0.99 (0.95 to 1.04)		1.06 (0.84 to 1.33)
Weight of thyroid specimen
By 100 g increase	1.00 (0.99 to 1.01)		1.23 (0.71 to 2.15)		1.00 (0.99 to 1.01)		1.34 (0.83 to 2.14)

*Included a surgical indication of Graves’ disease or malignant neoplasm, an extended thyroidectomy, or a thyroidectomy with lymph node dissection.

†Variation attributable to the patient, surgeon, and hospital centre levels was 58.6%, 10.3%, and 0.0%, respectively.

‡Variation attributable to the patient, surgeon, and hospital centre levels was 55.6%, 31.5%, and 0.0%, respectively.