Table 3.
Change Scores and Treatment Effects for Primary and Secondary Outcomes in the Randomized and Observational DS Cohorts Combined, According to BMI and Treatment Received*
| DS | 1-Year | 2-Year | 3-Year | 4-Year | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Outcome | BMI | Surgical | Non- operative |
Treatment Effect† (95% CI) |
Surgical | Non- operative |
Treatment Effect† (95% CI) |
Surgical | Non- operative |
Treatment Effect† (95% CI) |
Surgical | Non- operative |
Treatment Effect† (95% CI) |
| SF-36 Bodily Pain (BP) (0–100) (SE)†† |
BMI < 30 | 32.4 (1.6) | 15.7 (1.7) | 16.7 (12.4, 21) | 32.6 (1.6) | 15.1 (1.9) | 17.5 (13, 22) | 33 (1.6) | 17.4 (2) | 15.6 (10.8, 20.4) | 30.7 (1.7) | 16.9 (2.2) | 13.8 (8.7, 19) |
| 30 ≤ BMI < 35 | 29.2 (2.7) | 10.8 (3.1) | 18.4 (11, 25.8) | 29.3 (2.5) | 9.6 (3.4) | 19.6 (11.9, 27.4) | 30.8 (2.5) | 12.4 (3.7) | 18.4 (10.1, 26.6) | 31.6 (2.6) | 15.7 (4) | 15.9 (6.9, 24.8) | |
| BMI ≥ 35 | 34.4 (3) | 11 (3.8) | 23.5 (14.6, 32.3) | 30.4 (2.9) | 10.1 (4.1) | 20.4 (11.1, 29.7) | 31.3 (3) | 9.8 (4.7) | 21.5 (11, 32) | 29.6 (3.1) | 10.7 (4.6) | 19 (8.5, 29.5) | |
| pvalue | 0.40 | 0.26 | 0.39 | 0.47 | 0.26 | 0.80 | 0.72 | 0.23 | 0.55 | 0.89 | 0.48 | 0.67 | |
| SF-36 Physical Function (PF) (0–100) (SE)†† |
BMI < 30 | 31 (1.5) | 15.1 (1.7) | 15.9 (11.9, 20) | 29.9 (1.5) | 14.1 (1.8) | 15.8 (11.5, 20.1) | 28.1 (1.5) | 13.8 (1.9) | 14.4 (9.8, 18.9) | 27.9 (1.6) | 14 (2.1) | 13.9 (9, 18.8) |
| 30 ≤ BMI < 35 | 23.3 (2.6) | 5 (3) | 18.3 (11.3, 25.2) | 19.8 (2.5) | 2.1 (3.3) | 17.8 (10.4, 25.1) | 19.3 (2.4) | −0.4 (3.5) | 19.7 (11.9, 27.5) | 22.8 (2.5) | −2.6 (3.8) | 25.4 (16.9, 33.8) | |
| BMI ≥ 35 | 23.4 (2.9) | −0.7 (3.6) | 24.1 (15.8, 32.5) | 18.2 (2.8) | 0.1 (4) | 18 (9.2, 26.9) | 21.1 (2.9) | 1.6 (4.8) | 19.5 (9.1, 29.8) | 21.2 (3) | −4.8 (4.5) | 26 (15.9, 36.1) | |
| pvalue | 0.009 | <0.001 | 0.22 | <0.001 | <0.001 | 0.84 | 0.003 | <0.001 | 0.40 | 0.069 | <0.001 | 0.016 | |
| Mental Component Summary (MCS) (0–100) (SE)†† |
BMI < 30 | 2.2 (0.7) | 1.8 (0.7) | 0.4 (−1.4, 2.2) | 2.3 (0.6) | 1 (0.8) | 1.3 (−0.6, 3.2) | 2.5 (0.7) | 0.6 (0.8) | 1.9 (−0.2, 3.9) | 2.6 (0.7) | −0.2 (0.9) | 2.8 (0.5, 5.1) |
| 30 ≤ BMI < 35 | 1.8 (1.1) | 0.6 (1.3) | 1.2 (−1.9, 4.4) | 2.9 (1) | 1 (1.4) | 1.9 (−1.4, 5.2) | 2.3 (1) | −1.4 (1.5) | 3.7 (0.2, 7.2) | 1.9 (1.1) | 1 (1.7) | 0.9 (−3, 4.7) | |
| BMI ≥ 35 | 7.4 (1.2) | 0.9 (1.6) | 6.5 (2.7, 10.3) | 3.5 (1.2) | −0.2 (1.7) | 3.7 (−0.3, 7.6) | 3.5 (1.2) | 0 (2.1) | 3.5 (−1.1, 8.1) | 2.3 (1.3) | −0.7 (2.1) | 3 (−1.7, 7.8) | |
| pvalue | <0.001 | 0.66 | 0.015 | 0.60 | 0.82 | 0.55 | 0.72 | 0.52 | 0.59 | 0.88 | 0.76 | 0.67 | |
| Oswestry Disability Index (ODI) (0–100) (SE))‡‡ |
BMI < 30 | −25.2 (1.2) | −9.8 (1.3) | −15.4 (−18.5, −12.2) | −24.7 (1.2) | −10.2 (1.4) | −14.5 (−17.8, −11.1) | −22.7 (1.2) | −11 (1.5) | −11.7 (−15.2, −8.2) | −23.2 (1.3) | −10.5 (1.6) | −12.6 (−16.4, −8.8) |
| 30 ≤ BMI < 35 | −23.1 (2) | −5.8 (2.3) | −17.3 (−22.7, −11.9) | −22.5 (1.9) | −6 (2.6) | −16.5 (−22.2, −10.8) | −19.3 (1.9) | −7.8 (2.8) | −11.6 (−17.7, −5.5) | −22 (2) | −5.3 (3) | −16.8 (−23.3, −10.2) | |
| BMI ≥ 35 | −25 (2.3) | −2 (2.9) | −23 (−29.5, −16.5) | −22 (2.2) | −0.5 (3.1) | −21.5 (−28.3, −14.6) | −21.3 (2.3) | −2.4 (3.5) | −18.9 (−26.6, −11.2) | −21.3 (2.4) | −2.4 (3.4) | −18.8 (−26.5, −11.2) | |
| pvalue | 0.66 | 0.027 | 0.11 | 0.42 | 0.012 | 0.18 | 0.31 | 0.068 | 0.22 | 0.75 | 0.055 | 0.26 | |
| Stenosis Bothersomeness Index (0–24) (SE)§§ |
BMI < 30 | −9.5 (0.4) | −4.3 (0.5) | −5.2 (−6.4, −4) | −9.4 (0.4) | −4.3 (0.5) | −5.1 (−6.3, −3.8) | −9.4 (0.4) | −4.7 (0.6) | −4.7 (−6, −3.3) | −9.7 (0.5) | −4.6 (0.6) | −5.1 (−6.5, −3.7) |
| 30 ≤ BMI < 35 | −9 (0.7) | −3.1 (0.8) | −5.9 (−7.8, −3.9) | −8.2 (0.7) | −2.6 (0.9) | −5.6 (−7.7, −3.5) | −8.5 (0.7) | −2.6 (1) | −5.9 (−8.2, −3.7) | −8.3 (0.7) | −1.5 (1.1) | −6.8 (−9.2, −4.3) | |
| BMI ≥ 35 | −10.2 (0.8) | −2.6 (1) | −7.6 (−10, −5.2) | −9.1 (0.8) | −3.6 (1.1) | −5.5 (−8.1, −2.9) | −9.1 (0.8) | −4.5 (1.3) | −4.5 (−7.5, −1.6) | −8.2 (0.9) | −1.7 (1.3) | −6.5 (−9.4, −3.6) | |
| pvalue | 0.55 | 0.22 | 0.21 | 0.27 | 0.23 | 0.90 | 0.47 | 0.15 | 0.62 | 0.12 | 0.012 | 0.41 | |
| Low Back Pain Bothersomeness (0–6) (SE)¶¶ |
BMI < 30 | −2.4 (0.1) | −1.2 (0.1) | −1.2 (−1.6, −0.8) | −2.2 (0.1) | −1.3 (0.2) | −0.8 (−1.2, −0.4) | −2.1 (0.1) | −1.4 (0.2) | −0.7 (−1.1, −0.3) | −2.1 (0.1) | −1.3 (0.2) | −0.8 (−1.2, −0.4) |
| 30 ≤ BMI < 35 | −2.1 (0.2) | −1.1 (0.2) | −1.1 (−1.7, −0.5) | −2.1 (0.2) | −1 (0.3) | −1.1 (−1.7, −0.5) | −2.2 (0.2) | −1.2 (0.3) | −1 (−1.7, −0.3) | −2.1 (0.2) | −0.9 (0.3) | −1.1 (−1.8, −0.4) | |
| BMI ≥ 35 | −2.4 (0.2) | −0.5 (0.3) | −1.8 (−2.5, −1.1) | −2 (0.2) | −0.9 (0.3) | −1.1 (−1.8, −0.4) | −1.7 (0.2) | −1.5 (0.4) | −0.2 (−1.1, 0.7) | −2 (0.2) | −0.8 (0.4) | −1.2 (−2.1, −0.3) | |
| pvalue | 0.57 | 0.048 | 0.18 | 0.86 | 0.37 | 0.70 | 0.36 | 0.71 | 0.34 | 0.97 | 0.28 | 0.51 | |
| Very/somewhat satisfied with symptoms (%) |
BMI < 30 | 74.5 | 31.9 | 42.7 (33.2, 52.2) | 70.2 | 30.8 | 39.3 (29.2, 49.4) | 65.8 | 39.4 | 26.4 (15, 37.8) | 62.8 | 32.5 | 30.3 (18.2, 42.3) |
| 30 ≤ BMI < 35 | 70 | 20.1 | 49.9 (35.1, 64.8) | 67.6 | 34.2 | 33.5 (15.6, 51.4) | 65.4 | 25 | 40.4 (22.6, 58.1) | 62.7 | 25.7 | 37 (17.3, 56.8) | |
| BMI ≥ 35 | 67.6 | 14.7 | 52.9 (36, 69.8) | 67.8 | 39.6 | 28.2 (5.7, 50.7) | 66.3 | 39 | 27.3 (1.7, 52.9) | 65.8 | 14.5 | 51.3 (31, 71.5) | |
| pvalue | 0.57 | 0.083 | 0.49 | 0.90 | 0.70 | 0.64 | 0.99 | 0.32 | 0.47 | 0.94 | 0.42 | 0.43 | |
| Self-rated progress: major improvement (%) |
BMI < 30 | 73.2 | 28.8 | 44.4 (35, 53.8) | 74 | 26.2 | 47.9 (38.2, 57.5) | 73.8 | 25.4 | 48.4 (38.3, 58.5) | 65.5 | 21.9 | 43.7 (32.6, 54.7) |
| 30 ≤ BMI < 35 | 73.4 | 23 | 50.4 (35, 65.8) | 68.5 | 19.7 | 48.8 (33, 64.7) | 65.2 | 33.8 | 31.4 (11.9, 51) | 65.8 | 19.3 | 46.6 (27.7, 65.4) | |
| BMI ≥ 35 | 84 | 12.3 | 71.7 (57.4, 86.1) | 75.9 | 18.6 | 57.3 (39, 75.6) | 66.8 | 13.3 | 53.5 (33.7, 73.2) | 69.9 | 15.5 | 54.5 (33.5, 75.4) | |
| pvalue | 0.29 | 0.25 | 0.087 | 0.59 | 0.65 | 0.75 | 0.36 | 0.43 | 0.29 | 0.88 | 0.83 | 0.74 | |
Adjusted for age, gender, race, smoking status, compensation, joint, stomach, bowel, osteoporosis, number of moderate/severe stenotic levels, self-assessed health trend at baseline, treatment preference, baseline stenosis bothersomeness, other comorbiditiy, baseline score and center. Other comorbidities include: stroke, cancer, fibromyalgia, chronic fatigue syndrome, post traumatic stress disorder, alcohol, drug dependency, lung, liver, kidney, blood vessel, nervous system, migraine, anxiety.
Treatment effect is the difference between the surgical and non-operative mean change from baseline. Analysis is done using a mixed model with a random subject intercept term. Treatment is a time-varying covariate where a patients' experience prior to surgery is attributed to the non-operative arm and time is measured from enrollment and his/her post-surgery outcomes are attributed to the surgical arm and time is measured from time of surgery.
The SF-36 scores range from 0 to 100, with higher score indicating less severe symptoms.
The Oswestry Disability Index ranges from 0 to 100, with lower scores indicating less severe symptoms.
The Stenosis Bothersomeness index range from 0 to 24, with lower scores indicating less severe symptoms.
The Low Back Pain Bothersomeness Scale ranges from 0 to 6, with lower scores indicating less severe symptoms