Article Figures & Data
Tables
Characteristic Total (n = 634) Non-WC (n = 374) WC (n = 260) P Valuea Age, mean ± SD 50.8 ± 11.7 53.9 ± 11.7 46.4 ± 10.0 <0.001 Gender <0.001 Female 37.9% (240) 48.7% (182) 22.3% (58) Male 62.1% (394) 51.3% (192) 77.7% (202) Ethnicity <0.001 White 66.3% (420) 79.4% (297) 47.5% (123) Nonwhite 33.7% (213) 20.6% (77) 52.5% (136) Body mass index 0.003 <30 kg/m2 51.9% (328) 56.8% (212) 44.8% (116) ≥30 kg/m2 48.1% (304) 43.1% (161) 55.2% (143) Smoking status <0.001 Nonsmoker 80.8% (512) 86.1% (322) 73.0% (190) Smoker 19.2% (122) 13.9% (52) 26.9% (70) Diabetic status 0.976 Nondiabetic 88.8% (563) 88.8% (332) 88.9% (44) Diabetic 11.2% (71) 11.2% (42) 11.1% (4) American Society of Anesthesiologists Score 0.742 <2 82.8% (521) 83.2% (308) 82.2% (213) ≥2 17.2% (108) 16.7% (62) 17.8% (46) Charlson Comorbidity Index Score 0.001 ≤1 24.9% (154) 19.9% (73) 32.1% (81) >1 75.1% (464) 80.1% (293) 67.9% (171) Data presented as % (n) unless otherwise indicated. Boldface indicates statistical significance.
aP value calculated using χ 2 test or Student’s t test.
WC, workers’ compensation.
Characteristic Total (n = 121) Non-WC (n = 92) WC (n = 29) P Valuea Age, mean ± SD 53.5 ± 9.4 54.6 ± 9.7 50.0 ± 7.4 0.023 <50 y 34.7% (42) 31.5% (29) 44.8% (13) 50–64 y 62.0% (75) 64.1% (59) 55.2% (16) >65 y 3.3% (4) 4.3% (4) 0.0% (0) Gender 0.044 Female 36.4% (44) 41.3% (38) 20.7% (6) Male 63.6% (77) 58.7% (54) 79.3% (23) Ethnicity <0.001 White 78.5% (95) 87.0% (80) 51.7% (15) Nonwhite 21.5% (26) 13.0% (12) 48.3% (14) Body mass index 0.437 <30 kg/m2 54.5% (66) 56.5% (52) 48.3% (14) ≥30 kg/m2 44.5% (55) 43.5% (40) 51.7% (15) Smoking status 0.078 Nonsmoker 88.4% (107) 91.3% (84) 79.3% (23) Smoker 11.6% (14) 8.7% (8) 20.7% (6) Diabetic status 0.423 Nondiabetic 90.1% (109) 91.3% (84) 86.2% (25) Diabetic 9.9% (12) 8.7% (8) 13.8% (4) American Society of Anesthesiologists Score 0.794 <2 84.3% (102) 84.8% (80) 82.8% (24) ≥2 15.7% (19) 15.2% (14) 17.2% (5) Charlson Comorbidity Index Score 0.331 ≤1 23.6% (29) 26.1% (24) 17.2% (32) >1 76.4% (92) 73.9% (68) 82.8% (12) Duration of symptoms 0.005 <6 mo 20.4% (22) 19.5% (16) 23.1% (6) 6 mo to 1 y 21.3% (23) 14.6% (12) 42.3% (11) >1 y 58.3% (63) 65.9% (54) 34.6% (9) Time to surgery, mo, mean ± SD, mo (n) 4.9 ± 10.4 (114) 4.7 ± 11.4 (92) 5.9 ± 4.1 (22) 0.628 Data provided as % (n) unless otherwise indicated. Boldface indicates statistical significance.
aP value calculated using χ 2 test or Student’s t test.
WC, workers’ compensation.
Characteristic Total (n = 121) Non-WC (n = 92) WC (n = 29) P Valuea Spinal pathology Degenerative disc disease 55.3% (67) 53.3% (49) 62.1% (18) 0.405 Degenerative spondylolisthesis 65.4% (70) 61.9% (52) 78.3% (18) 0.144 Isthmic spondylolisthesis 24.3% (26) 28.6% (24) 8.7% (2) 0.049 Operative time, min, mean ± SD 124.5 ± 23.5 123.9 ± 23.2 126.1 ± 24.9 0.663 Estimated blood loss, mL, mean ± SD, mL 48.5 ± 25.2 48.5 ± 24.3 48.3 ± 28.3 0.962 Length of stay, h, mean ± SD 29.2 ± 18.7 29.4 ± 19.7 28.8 ± 15.4 0.877 Day of discharge 0.310 POD 0 19.0% (23) 18.5% (17) 20.7% (6) POD 1 61.2% (74) 63.0% (58) 55.1% (16) POD 2 15.7% (19) 13.0% (12) 24.1% (7) POD 3 4.1% (5) 5.5% (5) 0.0% (0) Data provided as % (n) unless otherwise indicated. Boldface indicates statistical significance.
aP value calculated using either χ 2 test or Student’s t test.
POD, postoperative day; WC, workers’ compensation.
Patient-Reported Outcome Measures Non-WC, Mean ± SD (n) P Valuea WC, Mean ± SD (n) P Valuea P Valueb VAS back Preoperative 6.0 ± 2.6 (92) – 6.7 ± 2.2 (29) – 0.297 6 wk 3.3 ± 2.6 (83) <0.001 5.1 ± 2.0 (25) 0.001 0.001 12 wk 2.6 ± 2.2 (76) <0.001 5.3 ± 2.5 (24) 0.004 <0.001 6 mo 2.5 ± 2.4 (75) <0.001 5.3 ± 2.5 (25) 0.007 <0.001 1 y 2.2 ± 2.4 (48) <0.001 4.7 ± 2.7 (13) 0.147 0.004 VAS leg Preoperative 5.3 ± 3.0 (92) – 5.0 ± 3.0 (29) – 0.475 6 wk 2.5 ± 2.5 (83) <0.001 4.1 ± 2.7 (25) 0.188 0.012 12 wk 1.9 ± 2.4 (77) <0.001 3.6 ± 2.7 (24) 0.032 0.004 6 mo 1.6 ± 2.5 (75) <0.001 3.4±2.5 (25) 0.044 <0.001 1 y 1.9 ± 2.9 (48) <0.001 4.1 ± 2.7 (13) 0.223 0.002 ODI Preoperative 35.8 ± 13.9 (92) – 45.1 ± 15.6 (29) – 0.003 6 wk 28.5 ± 18.1 (84) <0.001 46.6 ± 17.3 (25) 0.696 <0.001 12 wk 22.4 ± 15.8 (78) <0.001 43.5 ± 14.3 (24) 0.439 <0.001 6 mo 15.7 ± 13.6 (76) <0.001 39.1 ± 18.9 (25) 0.088 <0.001 1 y 15.7 ± 18.7 (48) <0.001 30.3 ± 21.3 (13) 0.071 0.009 SF-12 PCSy Preoperative 32.4 ± 8.0 (88) – 27.4 ± 6.6 (27) – 0.001 6 wk 34.0 ± 9.2 (77) 0.138 26.3 ± 6.0 (22) 0.319 0.001 12 wk 38.1 ± 10.6 (68) 0.001 27.5 ± 5.7 (23) 0.775 <0.001 6 mo 42.9 ± 11.0 (62) <0.001 28.3 ± 7.0 (18) 0.581 <0.001 1 y 43.1 ± 10.8 (54) <0.001 30.8 ± 10.1 (15) 0.401 <0.001 PROMIS-PF Preoperative 36.4 ± 4.9 (92) – 32.6 ± 5.3 (29) – 0.001 6 wk 38.2 ± 6.9 (77) 0.017 33.7 ± 5.5 (21) 0.444 0.004 12 wk 42.2 ± 6.4 (62) <0.001 37.2 ± 6.3 (18) 0.043 0.005 6 mo 45.3 ± 6.7 (63) <0.001 39.2 ± 7.3 (16) <0.001 0.003 1 y 47.2 ± 8.2 (57) <0.001 39.0 ± 8.5 (12) 0.022 0.004 Boldface indicates statistical significance.
aP value was calculated using paired t test.
bP values calculated using Mann-Whitney U test.
ODI, Oswestry Disability Index; PROMIS-PF, Patient-Reported Outcome Measurement Information System physical function; SF-12, 12-Item Short Form Physical Component Summary; VAS, visual analog scale; WC, workers’ compensation.
PROM Coeff 95% CI P Valuea P Valueb P Valuec VAS back Preoperative 0.7 −0.4 to 1.8 0.196 0.090 0.163 6 wk 1.8 0.7–2.9 0.002 0.006 0.003 12 wk 2.7 1.7–3.8 <0.001 <0.001 <0.001 6 mo 2.8 1.7–3.9 <0.001 <0.001 <0.001 1 y 2.5 0.9–4.1 0.002 0.054 0.005 VAS leg Preoperative −0.5 −1.7 to 0.8 0.480 0.548 0.539 6 wk 1.5 0.3–2.7 0.012 0.032 0.041 12 wk 1.7 0.5–2.9 0.005 0.005 0.002 6 mo 1.8 0.6–2.9 0.003 0.001 0.006 1 y 2.1 0.3–4.0 0.021 0.032 0.145 ODI Preoperative 9.4 3.2–15.7 0.003 0.001 0.002 6 wk 18.4 10.3–26.5 <0.001 <0.001 <0.001 12 wk 21.1 13.9–28.4 <0.001 <0.001 <0.001 6 mo 23.4 16.5–30.3 <0.001 <0.001 <0.001 1 y 14.6 2.5–26.7 0.019 0.009 0.018 SF-12 PCS Preoperative −5.6 −9.0 to –2.2 0.002 <0.001 0.002 6 wk −6.7 −10.9 to –2.7 0.001 0.002 0.001 12 wk −9.8 −14.3 to –5.2 <0.001 <0.001 <0.001 6 mo −14.7 −20.0 to 9.3 <0.001 <0.001 <0.001 1 y −12.2 −18.3 to –6.0 <0.001 0.001 0.001 PROMIS-PF Preoperative −4.0 −6.3 to –1.6 0.001 0.002 0.001 6 wk −4.5 −7.7 to –1.2 0.007 0.009 0.010 12 wk −5.0 −8.5 to –1.6 0.005 0.012 0.010 6 mo −6.1 −9.9 to –2.2 0.002 0.001 0.004 1 y −8.2 −13.4 to –2.9 0.003 0.011 0.009 Boldface indicates statistical significance.
aP value was calculated using simple linear regression to determine effect of workers’ compensation status and preoperative duration of symptoms.
bP value was calculated using multiple linear regression to determine effect of workers’ compensation while accounting for duration of preoperative symptoms.
cP values calculated using multiple linear regression to determine effect of workers’ compensation status while accounting for time to surgery.
ODI, Oswestry Disability Index; PROM, Patient-Reported Outcome Measures; PROMIS-PF, Patient-Reported Outcome Measurement Information System physical function; SF-12 PCS, 12-Item Short Form Physical Component Summary; VAS, visual analog scale; WC, workers’ compensation.
Outcome Measure Preop—6 wk Preop—12 wk Preop—6 mo Preop—1 y Overall VAS back Non-WC 63.9% (53) 77.6% (59) 72.0% (54) 77.1% (37) 85.9% (79) WC 52.0% (13) 50.0% (12) 60.0% (15) 61.5% (8) 68.9% (20) P valuea 0.286 0.009 0.261 0.258 0.040 VAS leg Non-WC 61.5% (51) 71.4% (57) 68.0% (52) 58.3% (28) 78.3% (72) WC 40.0% (10) 45.8% (11) 48.0% (12) 61.5% (8) 62.0% (18) P valuea 0.058 0.021 0.073 0.835 0.082 ODI Non-WC 40.5% (34) 44.9% (35) 61.8% (47) 66.7% (32) 75.0% (69) WC 24.0% (6) 16.7% (4) 36.0% (9) 46.1% (6) 43.3% (12) P valuea 0.133 0.013 0.024 0.176 0.001 SF-12 PCS Non-WC 33.8% (26) 52.9% (36) 69.3% (43) 75.9% (41) 73.9% (68) WC 18.1% (4) 30.4% (7) 22.2% (4) 53.3% (8) 48.3% (14) P valuea 0.161 0.062 <0.001 0.088 0.010 PROMIS-PF Non-WC 15.6% (12) 37.1% (23) 50.8% (32) 57.9% (33) 59.8% (55) WC 9.5% (2) 22.2% (4) 43.7% (7) 25.0% (3) 37.9% (11) P valuea 0.482 0.227 0.615 0.034 0.039 The following MCID values derived from Copay et al; VAS back = 1.2, VAS leg = 1.6, ODI = 12.8; or Parker et al; SF-12 = 4.0; PROMIS MCID values derived from Hung et al PROMIS-PF = 8.0.
Data presented as % (n). Boldface indicates statistical significance.
aP value was calculated for each category using logistic regression.
MCID, minimum clinically important difference; PROMIS-PF, Patient-Reported Outcome Measurement Information System physical function; SF-12 PCS, 12-Item Short Form Physical Component Summary; VAS, visual analog scale; WC, workers’ compensation.