Follow-up score, change score or percentage change score for determining clinical important outcome following surgery? An observational study from the Norwegian registry for Spine surgery evaluating patient reported outcome measures in lumbar spinal stenosis and lumbar degenerative spondylolisthesis

Table 1 Patient demographics and surgical data for patients operated for spinal stenosis and for degenerative spondylolisthesis

	Spinal stenosis		Degenerative spondylolisthesis
	N		N
Age; Yr ± SD	3858	66 ± 11	617	67 ± 10
Female, no (%)	3859	1919 (50%)	617	444 (72%)
ASA level (1–4); Mean ± SD	3759	2.0 ± 0.6	608	2.0 ± 0.5
ASA level 1, no (%)		681 (18%)	82 (13%)
ASA level 2, no (%)		2349 (61%)	429 (71%)
ASA level 3, no (%)		753 (19%)	97 (16%)
ASA level 4, no (%)		12(0.3%)	0
Body Mass Index; Mean (SD)	3547	27 ± 4	560	27.0 ± 5
Smokers, no (%)	3808	877 (23%)	609	115 (19%)
Laminectomy, no (%)	3859	1024 (27%)	617	239 (39%)
Midline preserving decompression, no (%)	3859	2835 (73%)	617	378 (61%)
Fusion, no (%)	3859	214 (6%)	617	297 (48%)
ODI; Mean (SD)	3837	40 ± 15	617	41 ± 15
EQ-5D; Mean (SD)	3535	0.37 ± 0.32	564	0.34 ± 0.32
NRS leg pain; Mean (SD)	3559	6.6 ± 2.2	569	6.7 ± 2.2
NRS back pain; Mean (SD)	3597	6.4 ± 2.2	573	6.9 ± 2.1

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