Impact of Gender on Postsurgical Outcomes in Patients Undergoing Anterior Cervical Discectomy and Fusion

Madhav R. Patel; Kevin C. Jacob; Alexander W. Parsons; Nisheka N. Vanjani; Michael C. Prabhu; Hanna Pawlowski; Kern Singh

doi:10.14444/8366

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Table 1

Patient demographics.

Characteristic	Women (n = 134)	Men (n = 179)	P Value^{^a}
Age, y, mean ± SD	47.7 ± 10.3	46.7 ± 10.1	0.373
Body mass index, kg/m², mean ± SD	28.9 ± 6.6	29.6 ± 5.0	0.287
Obesity status, % (n)			0.269
Nonobese	60.5% (81)	54.2% (97)
Obese	39.6% (53)	45.8% (82)
Ethnicity, % (n)			0.505
African-American	14.9% (20)	14.5% (26)
Asian	3.0% (4)	0.6% (1)
Hispanic	5.2% (7)	6.7% (12)
White	73.9% (99)	76.0% (136)
Other	3.0% (4)	2.2% (4)
Diabetic status, % (n)			0.169
Nondiabetic	91.0% (122)	95.0% (170)
Diabetic	9.0% (12)	5.0% (9)
Smoking status, % (n)			0.667
Nonsmoker	79.4% (104)	81.4% (144)
Smoker	20.6% (27)	18.6% (33)
Blood pressure, % (n)			0.874
Normotensive	74.8% (98)	74.0% (131)
Hypertensive	25.2% (33)	26.0% (46)
American Society of Anesthesiologists score, % (n)			0.719
≤2	89.6% (112)	88.2% (135)
>2	10.4% (13)	11.8% (18)
Charlson Comorbidity Index score, mean ± SD	2.0 ± 1.6	1.7 ± 1.6	0.101
Insurance type, % (n)			0.005
Medicare/Medicaid	9.0% (12)	5.0% (9)
Workers’ compensation	25.4% (34)	42.5% (76)
Private	65.7% (88)	52.5% (94)

Note: Boldface indicates significance.
↵a P value calculated using χ ² analysis or paired sample t test.

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Table 2

Perioperative characteristics.

Characteristic	Women (n = 134)	Men (n = 179)	P Value^{^a}
Spinal pathology, % (n)
Degenerative spondylolisthesis	0.8% (1)	1.1% (2)	0.739
Recurrent herniated nucleus pulposus	95.5% (128)	91.1% (163)	0.127
Central stenosis	18.7% (25)	29.1% (52)	0.035
Foraminal stenosis	6.7% (9)	5.0% (9)	0.525
Operative time, min, mean ± SD	55.1 ± 14.1	57.7 ± 14.5	0.120
Estimated blood loss, mL, mean ± SD	41.6 ± 19.8	41.1 ± 21.1	0.811
Length of stay, h, mean ± SD	24.9 ± 13.5	19.4 ± 12.6	<0.001
Postoperative narcotic consumption, mean ± SD
POD 0	47.0 ± 36.4	47.2 ± 45.2	0.975
POD 1	18.9 ± 18.8	20.5 ± 30.6	0.603
Day of discharge, % (n)			0.017
POD 0	26.3% (35)	42.9% (75)
POD 1	63.9% (85)	52.0% (91)
POD 2	9.0% (12)	4.6% (8)
POD 3	0.8% (1)	0.0% (0)
POD 4	0.0% (0)	0.6% (0)

Abbreviation: POD, postoperative day of discharge.
Note: Boldface indicates statistical significance.
↵a P value calculated using χ ² analysis or paired sample t test.

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Table 3

Impact of gender on PROMs.

PROM	Women (Mean ± SD)	P Value^{^a}	Men (Mean ± SD)	P Value^{^b}
VAS neck
Preoperative	6.4 ± 2.4	-	6.0 ± 2.2	-
6 wk	4.0 ± 2.5	<0.001	3.3 ± 2.6	<0.001
12 wk	2.9 ± 2.8	<0.001	2.9 ± 2.4	<0.001
6 mo	3.0 ± 2.8	<0.001	2.7 ± 2.5	<0.001
1 y	3.2 ± 3.1	0.006	3.5 ± 2.7	<0.001
2 y	4.2 ± 2.6	0.002	4.3 ± 2.9	0.042
VAS arm
Preoperative	6.5 ± 2.7	-	5.7 ± 2.5	-
6 wk	2.2 ± 2.7	<0.001	2.7 ± 2.5	<0.001
12 wk	3.1 ± 3.5	<0.001	2.5 ± 2.4	<0.001
6 mo	2.9 ± 3.3	<0.001	2.4 ± 2.5	<0.001
1 y	3.0 ± 2.7	0.011	4.0 ± 3.4	0.028
2 y	3.3 ± 2.8	0.005	3.9 ± 3.3	0.235
NDI
Preoperative	42.9 ± 19.6	-	40.9 ± 17.8	-
6 wk	30.5 ± 20.2	<0.001	32.5 ± 19.8	<0.001
12 wk	25.0 ± 19.7	<0.001	28.1 ± 20.4	<0.001
6 mo	25.4 ± 21.1	<0.001	22.0 ± 20.5	<0.001
1 y	23.9 ± 20.0	0.010	26.1 ± 23.6	<0.001
2 y	22.6 ± 16.0	0.004	33.7 ± 23.9	0.023
SF-12 PCS
Preoperative	37.6 ± 7.4	-	37.9 ± 10.5	-
6 wk	39.1 ± 9.4	0.019	38.0 ± 10.0	0.393
12 wk	44.5 ± 9.1	<0.001	43.8 ± 11.5	<0.001
6 mo	40.5 ± 10.0	0.003	43.4 ± 9.6	<0.001
1 y	44.3 ± 8.4	0.002	43.1 ± 12.2	0.007
2 y	46.1 ± 8.4	0.013	37.6 ± 13.1	0.218
PROMIS-PF
Preoperative	39.1 ± 6.6	-	40.8 ± 7.8	-
6 wk	42.4 ± 6.9	0.141	39.3 ± 7.3	0.550
12 wk	46.2 ± 11.2	0.003	45.4 ± 10.4	0.004
6 mo	45.9 ± 9.2	<0.001	47.4 ± 10.9	<0.001
1 y	47.1 ± 7.9	0.049	48.0 ± 9.4	0.002
2 y	48.3 ± 11.0	0.019	46.0 ± 9.6	0.004
VR-12 PCS
Preoperative	36.5 ± 7.5	-	36.4 ± 10.0	-
6 wk	40.2 ± 8.5	0.024	36.3 ± 10.1	0.928
12 wk	42.9 ± 10.1	0.012	40.7 ± 11.6	0.031
6 mo	42.9 ± 9.8	0.001	45.9 ± 9.3	<0.001
1 y	45.7 ± 8.5	0.006	44.7 ± 11.6	0.001
2 y	47.5 ± 7.9	0.011	38.7 ± 13.5	0.343

Abbreviations: NDI, Neck Disability Index; PCS, physical composite score; PROM, patient-reported outcome measure; PROMIS-PF, PROM information system physical function; SF-12 PCS, 12-item short form survey PCS; VAS, visual analog scale; VR-12 PCS, veterans RAND 12-item health survey PCS.
Note: Boldface indicates statistical significance.
↵a P values calculated using paired sample t test for improvement from preoperative to postoperative PROMs among women.
↵b P values calculated using paired sample t test for improvement from preoperative to postoperative PROMs among men.

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Table 4

Impact of gender on PROMs.

PROM	Women (Mean ± SD)	Men (Mean ± SD)	P Value^{^a}	P Value^{^b}
VAS neck
Preoperative	6.4 ± 2.4	6.0 ± 2.2	0.278	0.364
6 wk	4.0 ± 2.5	3.3 ± 2.6	0.138	<0.001
12 wk	2.9 ± 2.8	2.9 ± 2.4	0.877	<0.001
6 mo	3.0 ± 2.8	2.7 ± 2.5	0.600	0.003
1 y	3.2 ± 3.1	3.5 ± 2.7	0.647	0.357
2 y	4.2 ± 2.6	4.3 ± 2.9	0.892	0.735
VAS arm
Preoperative	6.5 ± 2.7	5.7 ± 2.5	0.076	0.121
6 wk	2.2 ± 2.7	2.7 ± 2.5	0.317	0.005
12 wk	3.1 ± 3.5	2.5 ± 2.4	0.245	0.009
6 mo	2.9 ± 3.3	2.4 ± 2.5	0.407	0.013
1 y	3.0 ± 2.7	4.0 ± 3.4	0.274	0.325
2 y	3.3 ± 2.8	3.9 ± 3.3	0.672	0.685
NDI
Preoperative	42.9 ± 19.6	40.9 ± 17.8	0.574	<0.001
6 wk	30.5 ± 20.2	32.5 ± 19.8	0.608	<0.001
12 wk	25.0 ± 19.7	28.1 ± 20.4	0.434	<0.001
6 mo	25.4 ± 21.1	22.0 ± 20.5	0.418	<0.001
1 y	23.9 ± 20.0	26.1 ± 23.6	0.712	0.684
2 y	22.6 ± 16.0	33.7 ± 23.9	0.217	0.457
SF-12 PCS
Preoperative	37.6 ± 7.4	37.9 ± 10.5	0.799	0.004
6 wk	39.1 ± 9.4	38.0 ± 10.0	0.490	0.002
12 wk	44.5 ± 9.1	43.8 ± 11.5	0.722	0.011
6 mo	40.5 ± 10.0	43.4 ± 9.6	0.214	0.166
1 y	44.3 ± 8.4	43.1 ± 12.2	0.692	0.314
2 y	46.1 ± 8.4	37.6 ± 13.1	0.043	0.120
PROMIS-PF
Preoperative	39.1 ± 6.6	40.8 ± 7.8	0.345	<0.001
6 wk	42.4 ± 6.9	39.3 ± 7.3	0.105	0.026
12 wk	46.2 ± 11.2	45.4 ± 10.4	0.793	0.153
6 mo	45.9 ± 9.2	47.4 ± 10.9	0.634	0.031
1 y	47.1 ± 7.9	48.0 ± 9.4	0.800	0.995
2 y	48.3 ± 11.0	46.0 ± 9.6	0.528	0.844
VR-12 PCS
Preoperative	36.5 ± 7.5	36.4 ± 10.0	0.923	0.003
6 wk	40.2 ± 8.5	36.3 ± 10.1	0.070	<0.001
12 wk	42.9 ± 10.1	40.7 ± 11.6	0.436	0.003
6 mo	42.9 ± 9.8	45.9 ± 9.3	0.207	0.090
1 y	45.7 ± 8.5	44.7 ± 11.6	0.735	0.803
2 y	47.5 ± 7.9	38.7 ± 13.5	0.035	0.093

Abbreviations: NDI, Neck Disability Index; PCS, physical composite score; PROM, patient-reported outcome measure; PROMIS-PF, PROM information system physical function; SF-12 PCS, 12-item short form survey PCS; VAS, visual analog scale; VR-12 PCS, veterans RAND 12-item health survey PCS.
Note: Boldface indicates statistical significance.
↵a P values calculated using simple linear regression of PROMs by gender.
↵b P values calculated using multiple regression of PROMs by gender and insurance type.

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Table 5

Impact of gender on minimal clinically important difference achievement.

Minimal Clinically Important Difference	6 wk	12 wk	6 mo	1 y	2 y	Overall
VAS arm	n = 49	n = 42	n = 39	n = 15	n = 5	n = 71
Women	51.3% (20)	44.7% (17)	34.3% (12)	29.4% (5)	25.0% (2)	64.4% (29)
Men	38.7% (29)	37.9% (25)	44.3% (27)	25.0% (10)	18.8% (3)	51.9% (42)
P value^{^a}	0.197	0.492	0.338	0.729	0.722	0.172
VAS neck	n = 58	n = 69	n = 61	n = 23	n = 9	n = 97
Women	43.2% (19)	68.2% (30)	64.1% (25)	31.6% (6)	33.3% (3)	72.6% (37)
Men	49.4% (39)	55.7% (39)	55.4% (36)	43.6% (17)	35.3% (6)	70.6% (60)
P value^{^a}	0.510	0.185	0.382	0.380	0.920	0.807
NDI	n = 54	n = 63	n = 62	n = 28	n = 14	n = 91
Women	56.4% (22)	71.1% (27)	67.7% (23)	58.8% (10)	77.8% (7)	75.0% (33)
Men	43.8% (32)	56.3% (36)	67.2% (39)	48.7% (18)	46.7% (7)	71.8% (56)
P value^{^a}	0.205	0.137	0.968	0.487	0.134	0.702
SF-12 PCS	n = 26	n = 42	n = 29	n = 16	n = 12	n = 76
Women	30.6% (11)	39.1% (18)	37.0% (10)	35.3% (6)	50.0% (7)	50.8% (32)
Men	25.0% (15)	34.3% (24)	48.7% (19)	35.7% (10)	35.7% (5)	47.8% (44)
P value^{^a}	0.553	0.595	0.347	0.977	0.445	0.717
PROMIS-PF	n = 19	n = 22	n = 24	n = 15	n = 19	n = 42
Women	42.9% (9)	60.0% (9)	66.7% (10)	50.0% (5)	57.1% (8)	72.0% (18)
Men	37.0% (10)	48.2% (13)	63.6% (14)	58.8% (10)	61.1% (11)	66.7% (24)
P value^{^a}	0.683	0.461	0.850	0.656	0.821	0.658

Abbreviations: NDI, Neck Disability Index; PROMIS-PF, patient-reported outcome measure information system physical function; SF-12 PCS, 12-item short form survey physical composite score; VAS, visual analog scale.
Note: Data presented as % (n). Boldface indicates statistical significance.
↵a P values calculated using χ ² analysis.