Can we define success criteria for lumbar disc surgery?

Figures & data

Table 1. Characteristics of the study population (n = 692) at baseline

Mean age (SD)	46 (13)
Females, n (%)	284 (41)
Smokers, n (%)	228 (33)
University or college education, n (%)	228 (33)
Received social benefits, including sickness benefit/pay, n (%)	442 (66)
Previous low back operation, n (%)	139 (20)
Days of hospital stay, mean (SD)	3 (3)
BMI, mean (SD)	27 (5)
ODI, mean (SD)	46 (18)
NRS back pain, mean (SD)	6 (3)
NRS leg pain, mean (SD)	7 (2)
EQ-5D, mean (SD)	0.26 (0.35)

BMI: body mass index.

Table 2. The mean change scores (95% CI) of the 4 instruments according to the global perceived change scale (anchor) at 1 year

		ODI	NRS back pain	NRS leg pain	EQ-5D
Global scale (categories)	n (%)	Mean change ^a	Mean change ^a	Mean change ^a	Mean change ^a
Completely recovered (1)	167 (24)	43 (42–45)	6 (5–6)	7 (6–7)	0.7 (0.7–0.7)
Much improved (2)	318 (46)	32 (31–33)	4 (4–4)	5 (5–5)	0.5 (0.5–0.5)
Slightly improved (3)	118 (17)	15 (13–17)	1 (1–2)	3 (3–4)	0.3 (0.3–0.3)
No change (4)	47 (7)	8 (5–10)	0 (0–0)	1 (0–1)	0 (0–0.1)
Slightly worsened (5)	15 (2)	0 (–5 to 5)	–1 (–1 to 0)	–1 (–2 to 0)	–0.1 (–0.2 to 0)
Much worsened (6)	18 (3)	–4 (–8 to 1)	–2 (–2 to –1)	0 (–1 to 1)	–0.1 (–0.2 to 0)
Worse than ever (7)	5 (1)	–21 (–30 to –13)	–2 (–4 to –1)	–1 (–3 to 1)	–0.4 (–0.5 to –0.2)
Total ^b	688	28 (27–29)	3 (3–3)	5 (4–5)	0.5 (0.5–0.5)

^a ANCOVA with adjustment for baseline scores.

^b Patients with complete data on all outcome measures.

ROC curves for Oswestry disability index (ODI), back and leg pain scores, and EuroQol (EQ-5D).

Table 3. The mean change scores (95% CI) according to the cutoffs for success for each of the 4 instruments. Values are mean change (95% confidence interval) ^a

	ODI	NRSback pain	NRSleg pain	EQ-5D
Success	37 (36–39)	5 (5–5)	6 (6–6)	0.7 (0.6–0.7)
No success	10 (9–12)	1 (0–1)	1 (1–2)	0.1 (0.1–0.2)

^a ANCOVA with adjustment for baseline scores; n = 688.

Table 4. Sensitivity analysis of area under the curve (AUC) with 95% CI and sensitivity/specificity (sens, spec) of cutoff values across 4 subgroups

	All		Operated with microsurgical technique		Operated with open discectomy		Operated for the first time		Previously operated
	(n = 692)		(n = 557)		(n = 135)		(n = 539)		(n = 139)
	AUC	Cutoff	AUC	Cutoff	AUC	Cutoff	AUC	Cutoff	AUC	Cutoff
	(95%CI)	(sens, spec)	(95%CI)	(sens, spec)	(95%CI)	(sens, spec)	(95%CI)	(sens, spec)	(95%CI)	(sens, spec)
ODI	0.85	20	0.86	20	0.84	20	0.87	20	0.83	20
	(0.83–0.89)	(0.78, 0.77)	(0.83–0.90)	(0.79, 0.77)	(0.77–0.92)	(0.77, 0.74)	(0.84–0.91)	(0.76, 0.80)	(0.75–0.90)	(0.83, 0.67)
NRS	0.82	2.5	0.83	2.5	0.79	2.5	0.83	2.5	0.80	2.5
back pain	(0.78–0.85)	(0.74, 0.77)	(0.79–0.86)	(0.74, 0.76)	(0.70–0.88)	(0.73, 0.81)	(0.79–0.87)	(0.73, 0.81)	(0.72–0.88)	(0.80, 0.67)
NRS	0.84	3.5	0.84	3.5	0.85	3.5	0.87	3.5	0.78	3.5
leg pain	(0.81–0.88)	(0.81. 0.73)	(0.80–0.88)	(0.81. 0.72)	(0.77–0.92)	(0.81. 0.73)	(0.83–0.90)	(0.81. 0.67)	(0.69–0.87)	(0.83. 0.64)
EQ-5D	0.80	0.3	0.80	0.3	0.79	0.3	0.82	0.3	0.72	0.3
	(0.76–0.84)	(0.74, 0.68)	(0.75–0.84)	(0.75, 0.67)	(0.71–0.87)	(0.67, 0.73)	(0.78–0.86)	(0.74, 0.72)	(0.63–0.81)	(0.72, 0.53)