How Do Patients With Predominant Neck Pain Improve After Anterior Cervical Discectomy and Fusion for Cervical Radiculopathy?

Srikanth N. Divi; Dhruv K.C. Goyal; Barrett I. Woods; Kristen J. Nicholson; Harold I. Salmons; Matthew S. Galetta; Mahir A. Qureshi; Meghan E. Lam; Andrew L. DiMatteo; D. Greg Anderson; Mark F. Kurd; Jeffrey A. Rihn; Ian D. Kaye; Christopher K. Kepler; Alan S. Hilibrand; Alexander R. Vaccaro; Kristen E. Radcliff; Gregory D. Schroeder

doi:10.14444/8212

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Table 1

Demographic data and surgical characteristics between visual analog scale pain groups.

Demographic	Neck (n = 46)	Neutral (n = 57)	Arm (n = 19)	Univariate Analysis, P Value^a
Age	52.0 (49.0, 54.0)	48.0 (46.0, 51.0)	49.0 (45.0, 53.0)	0.307
Sex
Men	24 (52.2%)	28 (49.1%)	7 (36.8%)	0.525
Women	22 (47.8%)	29 (50.9%)	12 (63.2%)
Body mass index	28.5 (27.0, 30.1)	29.4 (27.8, 31.0)	30.1 (27.3, 32.8)	0.497
Smoking status
Never	25 (45.3%)	29 (50.9%)	11 (57.9%)	0.824
Current	8 (17.4%)	13 (22.8%)	2 (10.5%)
Former	13 (37.3%)	15 (26.3%)	6 (31.6%)
Follow-Up, mo	20.2 (18.2, 22.3)	19.2 (18.0, 20.4)	20.7 (17.2, 24.2)	0.989
Worker's compensation received prior to surgery?
No	37 (80.4%)	49 (86.0%)	17 (89.5%)	0.598
Yes	9 (19.6%)	8 (14.0%)	2 (10.5%)
Levels fused
1	19 (41.3%)	18 (31.6%)	5 (26.3%)	0.357
2	17 (37.0%)	32 (56.1%)	9 (47.4%)
3	10 (21.7%)	7 (12.3%)	5 (26.3%)
Revision surgery?
No	42 (91.3%)	51 (89.5%)	17 (89.5%)	—
Yes	4 (8.7%)	6 (10.5%)	2 (10.5%)

Data presented as n (%) and median (IQR). Kruskal-Wallis H test, Pearson Χ ² analysis, or Fisher exact test were used to compare baseline demographics and surgical characteristics between groups.
aP < 0.05.

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Table 2

Patient-reported outcome measurements between VAS pain groups.

PROM	Interval	N (n = 46)	NE (n = 57)	A (n = 19)	Univariate Analysis, P Value		Multivariate Regression, β Coefficient (95% CI), P Value
PROM	Interval	N (n = 46)	NE (n = 57)	A (n = 19)	Paired Samples t Test	Kruskal-Wallis H Test or χ² Analysis	Multivariate Regression, β Coefficient (95% CI), P Value
PCS-12	Preoperative	32.7 (31.0, 34.5)	32.9 (30.9, 34.8)	35.3 (30.7, 39.9)	N: <0.001^aNE: <0.001^aA: 0.064	0.762	N: -NE: 2.300 (−1.707, 6.306), 0.258A: −0.532 (−6.015, 4.951), 0.848
	Postoperative	39.4 (35.9, 42.8)	41.4 (38.5, 44.4)	40.0 (34.1, 46.0)		0.617
	Delta	6.6 (3.3, 10.0)	8.3 (6.0, 10.6)	4.7 (−0.3, 9.8)		0.323
	RR	9.6%	12.1%	6.8%	—	0.419
	% MCID	39.1%	50.9%	36.8%	—	0.382
MCS-12	Preoperative	47.6 (43.8, 51.4)	46.4 (43.0, 49.7)	46.2 (40.8, 51.6)	N: 0.401NE: 0.076A: 0.318	0.836	N: -NE: 3.772 (−0.551, 8.096), 0.087A: 4.791 (−1.066, 10.648), 0.108
	Postoperative	45.8 (42.4, 49.2)	49.6 (46.7, 52.5)	49.8 (43.0, 56.6)		0.072
	Delta	−1.8 (−6.0, 2.4)	2.8 (−0.7, 6.4)	3.6 (−3.8, 11.1)		0.161
	RR	−7.7%	1.9%	4.3%	—	0.130
	% MCID	26.1%	40.4%	42.1%	—	0.255
NDI	Preoperative	45.0 (41.0, 50.0)	47.0 (41.0, 52.0)	37.0 (28.0, 46.0)	N: <0.001^aNE: <0.001^aA: <0.001^a	0.177	N: -NE: −7.554 (−15.211, 0.103), 0.053A: −10.571 (−21.102, −0.041), 0.049^a
	Postoperative	33.6 (26.6, 40.5)	27.5 (20.9, 34.1)	19.7 (10.6, 28.8)		0.063
	Delta	−11.6 (−17.4, −5.9]	−19.3 (−25.0, −13.5)	−17.4 (−25.8, −9.0)		0.330
	RR	25.6%	40.0%	51.7%	—	0.106
	% MCID	45.7%	50.9%	52.6%	—	0.825
VAS neck	Preoperative	6.5 (6.0, 7.0)	6.8 (6.2, 7.4)	4.3 (3.0, 5.5)	N: <0.001^aNE: <0.001^aA: 0.025^a	0.001^a	N: -NE: −1.020 (−2.128, 0.087), 0.071A: −1.170 (−2.782, 0.442), 0.153
	Postoperative	4.2 (3.3, 5.1)	3.2 (2.4, 3.9)	2.5 (1.2, 3.7)		0.065
	Delta	−2.3 (−3.2, −1.4)	−3.6 (−4.4, −2.7)	−1.8 (−3.4, −0.2)		0.082
	RR	34.2%	51.1%	29.1%	—	0.197
	% MCID	47.8%	59.6%	42.1%	—	0.302
VAS arm	Preoperative	3.0 (2.2, 3.9)	6.8 (6.2, 7.4)	6.3 (5.1, 7.5)	N: 0.362NE: <0.001^aA: 0.001^a	<0.001^a	N: -NE: −1.521 (−2.921, –0.121), 0.034^aA: −1.505 (−3.219, 0.210), 0.085
	Postoperative	3.5 (2.6, 4.5)	2.8 (2.0, 3.6)	3.1 (1.6, 4.6)		0.541
	Delta	0.5 (−0.6, 1.7)	−4.0 (−4.8, −3.2)	−3.1 (−4.8, –1.5)		<0.001^a
	RR	36.2%	58.7%	51.1%	—	0.263
	% MCID	19.6%	63.2%	42.1%	—	<0.001^a

Note: NPreoperative, postoperative, and delta data are presented as mean (95% CI). Neck, neutral, and arm pain dominant groups outcomes compared with univariate analysis—paired samples t test, Kruskal-Wallis H testing with Dunn multiple pairwise comparisons conducted for post hoc analysis, or Pearson Χ ² analysis—and multivariate regression. RR were defined as: (delta outcome score/[optimal outcome score – observed outcome score]), where the following optimal outcome scores were used: 100 (PCS-12 and MCS-12) or 0 (NDI). The percentage of patients reaching the MCID was based on the following threshold values: PCS-12, 8.1 points; MCS-12, 4.7 points; and NDI, 15 points. Multivariate regression analysis conducted using the neck pain dominant group as a baseline for comparison—controlling for age, sex, body mass index, smoking status, (never, current, and former), follow-up (mo), and No. of levels fused.
aIndicates statistical significance (P < 0.05).
A, arm; MCID, minimum clinically important difference; MCS-12, Mental Component Score of the Short Form-12 Survey; N, neck; NDI, Neck Disability Index; NE, neutral; PCS-12, Physical Component Score of the Short Form-12 Survey; RR, recovery ratios; VAS, visual analog scale.

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Table 3

Patient-reported outcome measurements between VAS ANR groups.

PROM	Interval	NAPD (ANR ≤1.0) (n = 91)	APD (ANR >1.0) (n = 31)	Univariate Analysis, P Value		Multivariate Regression, β Coefficient (95% CI), P Value
PROM	Interval	NAPD (ANR ≤1.0) (n = 91)	APD (ANR >1.0) (n = 31)	Paired Samples t Test	Independent Samples t Test or χ² Analysis	Multivariate Regression, β Coefficient (95% CI), P Value
PCS-12	Preoperative	33.1 (31.6, 34.5)	33.6 (30.6, 36.5)	NAPD: <0.001^aAPD: <0.001^a	0.691	NAPD: -APD: 0.675 (−3.647, 4.998), 0.757
	Postoperative	40.0 (37.6, 42.4)	41.8 (37.5, 46.0)		0.412
	Delta	6.9 (4.8, 9.0)	7.7 (3.9, 11.6)		0.522
	RR	10.2%	10.7%	—	0.661
	% MCID	41.8%	51.6%	—	0.340
MCS-12	Preoperative	47.0 (44.4, 49.7)	46.0 (41.9, 50.2)	NAPD: 0.903APD: 0.031^a	0.615	NAPD: -APD: 4.179 (−0.466, 8.823), 0.077
	Postoperative	46.9 (44.5, 49.3)	52.1 (47.9, 56.3)		0.008^a
	Delta	−0.2 (−3.0, 2.7)	5.5 (−0.1, 11.0]		0.043^a
	RR	0.0%	0.1%	—	0.114
	% MCID	30.8%	48.4%	—	0.076
NDI	Preoperative	46.0 (42.0, 50.0)	42.0 (35.0, 48.0)	NAPD: <0.001^aAPD: <0.001^a	0.243	NAPD: -APD: −9.808 (−18.053, –1.563), 0.020^a
	Postoperative	31.9 (26.8, 37.0)	18.8 (12.2, 25.4)		0.011^a
	Delta	−13.9 (−18.0, –9.7)	−22.8 (−30.2, –15.4)		0.038^a
	RR	31.1%	51.7%	—	0.059
	% MCID	45.1%	61.3%	—	0.118
VAS neck	Preoperative	6.5 (6.0, 7.0)	5.6 (4.8, 6.5)	NAPD: <0.001^aAPD: 0.001^a	0.041^a	NAPD: -APD: −0.704 (−1.929, 0.552), 0.258
	Postoperative	3.8 (3.1, 4.4)	2.5 (1.6, 3.3)		0.076
	Delta	−2.8 (−3.4, –2.1)	−3.0 (−4.1, –1.8)		0.504
	RR	41.2%	42.1%	—	0.331
	% MCID	51.6%	54.8%	—	0.748
VAS arm	Preoperative	4.7 (4.1, 5.4)	7.0 (6.3, 7.7)	NAPD: <0.001^aAPD: <0.001^a	0.001^a	NAPD: -APD: −0.942 (−2.268, 0.384), 0.162
	Postoperative	3.3 (2.7, 4.0)	2.5 (1.5, 3.5)		0.264
	Delta	−1.4 (−2.2, –0.6)	−4.4 (−5.6, –3.2)		0.001^a
	RR	48.3%	57.4%	—	0.499
	% MCID	37.4%	61.3%	—	0.020^a

Note: Preoperative, postoperative, and delta data are presented as mean (95% CI). VAS ANR group outcomes compared with univariate analysis—paired samples t test, Kruskal-Wallis H testing with Dunn multiple pairwise comparisons conducted for post hoc analysis, or Pearson Χ ² analysis—and multivariate regression. RR were defined as: (delta outcome score/[optimal outcome score – observed outcome score]), where the following optimal outcome scores were used: 100 (PCS-12 and MCS-12) or 0 (NDI).² The percentage of patients reaching the % MCID was based on the following threshold values: PCS-12, 8.1 points; MCS-12, 4.7 points; and NDI, 15 points.^3,4 Multivariate regression analysis conducted using the neck pain dominant group as a baseline for comparison—controlling for age, sex, Body Mass Index, smoking status, (never, current, former), follow-up (months), and No. of levels fused.
aIndicates statistical significance (P < 0.05).
ANR, arm neck ratio; APD, arm pain dominant; MCID, minimum clinically important difference; MCS-12 , Mental Component Score of the Short Form-12 Survey; NAPD, non-arm pain dominant; NDI , Neck Disability Index ; PCS-12 , Physical Component Score of the Short Form-12 Survey; RR, recovery ratios; VAS, visual analog scale.