Table 2.

Postoperative clinical outcomes for responsive non-respondents and respondents operated for lumbar spinal stenosis

	N Missing	Responsive non-respondents* Mean (SD) / n (%)	N Missing	Respondents** Mean (SD)/ n (%)	Mean diff (95% CI) or Relative risk (95% CI)	P-value
ODI	N = 64 Missing = 0	28.2 (19.9)	N = 333 Missing = 1	25.2 (18.9)	2.99 (-2.1 to 8.1)	0.250
NRS back pain	N = 64 Missing = 0	4.6 (3.0)	N = 328 Missing = 5	4.1 (2.9)	0.43 (-0.3 to 1.2)	0.271
NRS leg pain	N = 63 Missing 1	4.0 (3.2)	N = 321 Missing = 12	3.9 (3.1)	0.15 (-0.7 to 1.0)	0.719
Success by GPE***	N = 63 Missing 1	63 (70%)	N = 330 Missing = 3	330 (79%)	0.89 (0.8 to 1.1)	0.183

^* PROM scores collected retrospectively at a median of 50 months after surgery

^**PROM scores collected prospectively at 12 months after surgery

^***Success defined as “completely recovered” or “much recovered” on the GPE scale