Table 1.

Baseline characteristics and perioperative data of 474 patients with lumbar stenosis who reported to NORspine

	N Missing	Non-respondents (SD, %)	N Missing	Respondents (SD, %)	Mean difference (95% CI) or relative risk (95% CI)	P value
Age (years)	N = 140 Missing = 0	63.0 (11.7)	N = 334 Missing = 0	67.7 (9.9)	-4.7 (-6.74 to -2.59)	< 0.001
Female	N = 140 Missing = 0	71 (51%)	N = 334 Missing = 0	183 (55%)	0.93 (0.77 to 1.12)	0.426
BMI	N = 136 Missing = 4	28.6 (4.5)	N = 329 Missing = 5	28.2 (4.5)	0.4 (-0.48 to 1.33)	0.362
Comorbidities*	N = 135 Missing = 5	93 (69%)	N = 310 Missing = 24	243 (78%)	0.89 (0.77 to 1.00)	0.047
ASA grade I and II	N = 140 Missing = 0	111 (79%)	N = 334 Missing = 0	242 (72%)	1.09 (0.98 to 1.22)	0.100
Smokers	N = 138 Missing = 2	41 (30%)	N = 331 Missing = 3	70 (21%)	1.40 (1.01 to 1.95)	0.044
Norwegian as first language	N = 138 Missing = 2	130 (94%)	N = 331 Missing = 3	324 (98%)	0.96 (0.92 to 1.01)	0.090
University or college education > 4 years	N = 136 Missing = 4	30 (22%)	N = 328 Missing = 6	83 (25%)	0.87 (0.60 to 1.26)	0.463
Single civil status	N = 139 Missing = 1	30 (22%)	N = 332 Missing = 2	85 (26%)	0.84 (0.58 to 1.22)	0.361
Preoperative ODI	N = 136 Missing = 4	42.3 (16.1)	N = 329 Missing = 5	40.4 (15.8)	1.87 (-1.31 to 5.06)	0.248
Preoperative NRS back pain	N = 127 Missing = 13	6.9 (2.0)	N = 312 Missing = 22	6.8 (2.1)	0.17 (-0.26 to 0.61)	0.430
Preoperative NRS leg pain	N = 123 Missing = 17	6.9 (2.2)	N = 311 Missing = 23	7.0 (2.1)	-0.04 (-0.49 to 0.40)	0.844
Decompression only type surgery	N = 140 Missing = 0	122 (87%)	N = 334 Missing = 0	301 (90%)	0.98 (0.84 to 1.15)	0.820
Fusion type surgery	N = 140 Missing = 0	18 (13%)	N = 334 Missing = 0	33 (10%)	1.27 (0.74 to 2.18)	0.393

^* Comorbidities that were assessed as relevant by the reporting surgeon