Pain drawings predict outcome of surgical treatment for degenerative disc disease in the cervical spine

Figures & data

Table 1. Demographics at baseline.

Patient characteristics	Total n
Age, median (min, max)	130	46 (31, 61)
Women/men, n	130	67/63
Smokers, n (%)	130	39 (30)
Non-smokers, n (%)	130	91 (70)
In work, n (%)	128	111 (87)
Not in work, n (%)	128	17 (13)
ΔNDI 2y, median (min, max)	122	–22 (–66, 22)
ΔNDI 5y, median (min, max)	115	–28 (–74, 28)

NDI: Neck Disability Index; ΔNDI 2y: NDI at 2 years of follow-up minus preoperative NDI; ΔNDI 5y: NDI at 5 years of follow-up minus preoperative NDI.

Table 2. Principles of dichotomization of the various methods.

Method	Neurogenic	Non-neurogenic
Ransford (penalty points)	0–2	3+
Udén	N, PN	NN, PNN
Gatchel (ticked boxes, n)	0–19	20+

Table 3. Percentage pain drawings assessed to each group.

Method	Percentage of assessedpain drawings
Ransford
Neurogenic	49.6%
Non-neurogenic	50.4%
Udén
Neurogenic	72.1%
Non-neurogenic	27.9%
Gatchel
Neurogenic	44.6%
Non-neurogenic	55.4%
Ohnmeiss
Head
0	78.3%
1	21.7%
Neck
0	20.0%
1	80.0%
Shoulder
0	4.6%
1	95.4%
Upper arm
0	9.2%
1	90.8%
Lower arm
0	3.3%
1	96.7%
Bilateral
0	75.6%
1	24.4%

Table 4. Results of the reliability analysis.

Method	% agreement(all three evaluators)	Light’s κ(all three evaluators)	Cohen’s κ(less very experienced evaluator)	Cohen’s κ(re-evaluation same observer)
Ransford	42	0.29	0.50	0.72
Udén	61	0.36	0.43	0.50
Gatchel	85	0.79	0.80	0.88
Ohnmeiss
Head	90	0.80	0.89	0.87
Neck	91	0.81	0.78	0.91
Shoulder	98	0.88	0.90	0.82
Upper arm	95	0.81	0.89	0.95
Lower arm	100	1.00	1.00	1.00
Bilateral	93	0.88	0.86	0.98

Table 5. Results from method comparison.

Method	NDI, preopMean diff. (95% CI) P	ΔNDI 2 y (2 y NDI–preop NDI)Mean diff. (95% CI) P	ΔNDI 5 y (5 y NDI–preop NDI)Mean diff. (95% CI) P
Ransford	5.4 (2.0, 8.7) 0.0031	–0.8 (–5.0, 3.5) 0.72	0.7 (–4.4, 5.6) 0.78
Udén	4.2 (0.5, 8.0) 0.031	1.9 (–3.6, 7.2) 0.50	2.0 (–4.0, 7.7) 0.49
Gatchel	6.9 (2.4, 11.5) 0.002	2.0 (–1.6, 5.7) 0.55	3.6 (–3.1, 9.7) 0.27
Ohnmeiss
Head	7.5 (2.8, 12.2) 0.002	–0.5 (–8.4, 7.8) 0.91	–1.5 (–10.3, 7.5) 0.74
Neck	5.3 (–1.5, 12.1) 0.12	4.1 (–4.1, 12.5) 0.32	4.5 (–4.1, 13.4) 0.31
Shoulder	11.4 (–4.1, 26.3) 0.13	–13.0 (–18.6, –5.9) < 0.001	–8.6 (–21.9, 9.3) 0.29
Upper arm	–0.2 (–8.5, 6.9) 0.96	–10.4 (–18.3, –2.0) 0.014	–12.1 (–17.4, –6.1) < 0.001
Lower arm	8.6 (–10.0, 23.8) 0.31	–2.1 (–11.8, 10.2) 0.72	1.7 (–16.4, 12.3) 0.80
Bilateral	4.1 (–1.2, 9.6) 0.13	2.1 (–5.9, 10.0) 0.60	3.8 (–4.7, 11.8) 0.37

The values are:

The mean difference between preoperative NDI in group N and NN, group 1 and 0.

The mean difference between ΔNDI in group N and group NN, group 1 and group 0.

The mean difference between ΔNDI at the 5-year follow-up, in group N and group NN, group 1 and group 0.

Difference in means presented for each method. The endpoint mean for the N group is subtracted from the endpoint mean in the NN group. For the Ohnmeiss method, the endpoint mean for the group 0 (no markings) was subtracted from the endpoint mean in group 1 (with markings). Hence positive values correspond to larger values on preoperative NDI for the NN group or (for Ohnmeiss) for group 1. For the endpoints representing a change (ΔNDI) this typically means less negative values, i.e. closer to zero, suggesting that the NN group (or group 1) performs ‘worse’.

Table 6. ΔNDI at 2 years and 5 years postoperative, for all evaluation methods and for the totality of all observers.

Method	ΔNDI 2 y median(range)	ΔNDI 5 y median(range)
Ransford
Neurogenic	–22 (–66, 22)	–30 (–75, 28)
Non-neurogenic	–23 (–66, 22)	–28 (–74, 12)
Udén
Neurogenic	–24 (–66, 22)	–30 (–72, 28)
Non-neurogenic	–18 (–66, 12)	–22 (–74, 8)
Gatchel
Neurogenic	–22 (–66, 12)	–32 (–70, 28)
Non-neurogenic	–24 (–66, 22)	–28 (–74, 12)
Ohnmeiss
Head
0	–22 (–66, 12)	–28 (–74, 28)
1	–26 (–66, 22)	–30 (–72, 12)
Neck
0	–24 (–66, 6)	–31 (–74, 4)
1	–22 (–66, 22)	–28 (–72, 28)
Shoulder
0	–8 (–22, –4)	–16 (–58, 2)
1	–24 (–66, 22)	–30 (–74, 28)
Upper arm
0	–16 (–42, 6)	–16 (–48, –2)
1	–26 (–66, 22)	–30 (–74, 28)
Lower arm
0	–18 (–32, –12)	–36 (–40, –10)
1	–22 (–66, 22)	–28 (–74, 28)
Bilateral
0	–24 (–66, 22)	–30 (–72, 28)
1	–18 (–66, 12)	–20 (–74, 4)

Entries are median (min, max).