Table 2.
Multivariate Model Predicting Lumbar Spine Surgery by Three Years from Baseline Variables
| Domain and variables | Bivariate OR^ | Bivariate 95% CI | Multivariate OR^^ | Multivariate 95% CI | Multivariate P-Value |
|---|---|---|---|---|---|
| Sociodemographics | |||||
| Age, years (ref= 35–44 years) | 0.003 | ||||
| ≤24 years | 0.15 | 0.05 – 0.41 | 0.23 | 0.07 – 0.73 | |
| 25 – 34 years | 0.42 | 0.26 – 0.66 | 0.49 | 0.27 – 0.89 | |
| 45 – 54 years | 0.86 | 0.59 – 1.27 | 0.70 | 0.41 – 1.18 | |
| ≥ 55 years | 1.00 | 0.61 – 1.66 | 1.43 | 0.73 – 2.82 | |
| Gender (ref=male) | 0.0001 | ||||
| Female | 0.73 | 0.51 – 1.04 | 0.40 | 0.25 – 0.65 | |
| Region of worker residence (ref=urban) | 0.17 | ||||
| Suburban | 1.77 | 1.16 – 2.69 | 2.00 | 1.17 – 3.41 | |
| Large town | 1.02 | 0.60 – 1.75 | 1.31 | 0.65 – 2.64 | |
| Rural | 1.15 | 0.65 – 2.03 | 1.08 | 0.55 – 2.13 | |
| Race/ethnicity (ref=White non-Hispanic) | 0.002 | ||||
| Hispanic | 0.36 | 0.20 – 0.67 | 0.30 | 0.14 – 0.66 | |
| Other | 0.56 | 0.33 – 0.95 | 0.51 | 0.26 – 0.9991 | |
| Employment-related | |||||
| Fast pace (ref=strongly disagree/disagree) | 0.25 | ||||
| Agree | 1.21 | 0.78 – 1.88 | 1.45 | 0.81 – 2.61 | |
| Strongly agree | 1.78 | 1.16 – 2.74 | 1.63 | 0.90 – 2.95 | |
| Job duration ≥ 6 months | 0.71 | ||||
| < 6 months | 1.38 | 0.95 – 1.98 | 1.10 | 0.68 – 1.77 | |
| Employer offered job accommodation (ref=Yes) | 0.43 | ||||
| No/don’t know | 1.77 | 1.26 – 2.48 | 1.22 | 0.74 – 2.01 | |
| Returned to paid work by baseline interview (ref=Yes, same job) | 0.74 | ||||
| Yes, light duty or different job | 2.44 | 1.25 – 4.76 | 1.23 | 0.55 – 2.88 | |
| No | 8.28 | 4.72 – 14.56 | 1.34 | 0.64 – 2.79 | |
| Pain and function | |||||
| Number pain sites (ref=0–2 sites) | 0.60 | ||||
| 3 – 4 sites | 5.15 | 3.34 – 7.94 | 1.34 | 0.76 – 2.35 | |
| 5 – 8 sites | 4.22 | 2.50 – 7.11 | 1.28 | 0.65 – 2.52 | |
| Pain intensity, past week (0= no pain, ref= 0–3)49 | 0.18 | ||||
| 4 – 5 | 5.50 | 2.42 – 12.48 | 2.39 | 0.90 – 6.36 | |
| 6 – 7 | 8.23 | 3.68 – 18.37 | 1.67 | 0.62 – 4.49 | |
| 8 – 10 | 15.26 | 6.90 – 33.72 | 2.36 | 0.86 – 6.50 | |
| Roland-Morris Disability Questionnaire34 € (0=no disability) (ref=0–8) | 0.0003 | ||||
| 9 – 16 | 8.55 | 3.02 – 24.19 | 2.52 | 0.78 – 8.10 | |
| 17 – 24 | 31.69 | 11.59 – 86.63 | 6.12 | 1.84 – 20.42 | |
| Pain change since injury (ref=better) | 0.50 | ||||
| Same | 3.31 | 2.24 – 4.87 | 1.06 | 0.62 – 1.80 | |
| Worse | 6.72 | 4.46 – 10.12 | 1.56 | 0.84 – 2.90 | |
| Clinical status | |||||
| Injury severity (ref=mild strain/sprain) | <0.0001 | ||||
| Major strain/sprain with substantial immobility but no evidence of radiculopathy | 1.36 | 0.78 – 2.38 | 0.84 | 0.43 – 1.62 | |
| Evidence of radiculopathy | 7.80 | 5.21 – 11.68 | 4.34 | 2.62 – 7.17 | |
| Reflex, sensory or motor abnormalities | 11.57 | 6.19 – 21.65 | 5.73 | 2.62 – 12.52 | |
| Previous injury (any type) with ≥ 1 month off work (ref=no) | 0.32 | ||||
| Yes | 1.83 | 1.32 – 2.54 | 1.19 | 0.86 – 1.66 | |
| Opioid Rx within 6 weeks of injury (ref=no) | 0.38 | ||||
| Yes | 2.46 | 1.78 – 3.39 | 0.87 | 0.65 – 1.18 | |
| Health care | |||||
| Specialty, first provider seen for injury (ref=primary care) | <0.0001 | ||||
| Surgeon | 10.41 | 6.72 – 16.11 | 8.69 | 5.03 – 15.01 | |
| Occupational medicine | 2.09 | 1.13 – 3.87 | 1.39 | 0.67 – 2.87 | |
| Chiropractor | 0.21 | 0.10 – 0.45 | 0.22 | 0.10 – 0.50 | |
| Other | 1.36 | 0.84 – 2.19 | 1.38 | 0.78 – 2.45 | |
| Time from injury to first medical visit for injury (ref=0–6 days) | 0.32 | ||||
| 7 – 13 days | 1.08 | 0.65 – 1.79 | 0.74 | 0.39 – 1.40 | |
| ≥ 14 days | 2.58 | 1.67 – 3.98 | 1.49 | 0.82 – 2.72 | |
| Health behavior | |||||
| Tobacco use (ref=no) | 0.38 | ||||
| Occasionally/frequently | 1.04 | 0.64 – 1.67 | 0.66 | 0.36 – 1.21 | |
| Daily | 1.49 | 1.06 – 2.11 | 0.95 | 0.60 – 1.50 | |
| Psychological | |||||
| Catastrophizing50 ‡‡ (ref=0–1) | 0.18 | ||||
| Low (>1 – <2) | 3.02 | 1.55 – 5.90 | 1.75 | 0.73 – 4.18 | |
| Moderate (2 – <3) | 5.30 | 2.99 – 9.42 | 2.28 | 1.05 – 4.93 | |
| High (3 – 4) | 6.39 | 3.57 – 11.43 | 2.15 | 0.94 – 4.90 | |
| Recovery expectations50 (0–10 scale, 10 = extremely certain will be working in 6 months, ref=10) | 0.38 | ||||
| High (7 – 9) | 3.04 | 2.10 – 4.40 | 0.87 | 0.51 – 1.48 | |
| Low (0 – 6) | 1.86 | 1.22 – 2.84 | 0.97 | 0.56 – 1.67 | |
| Blame for injury51 (ref=work) | 0.09 | ||||
| Self | 0.52 | 0.31 – 0.85 | 0.72 | 0.38 – 1.35 | |
| Someone/something else | 1.25 | 0.81 – 1.92 | 1.17 | 0.67 – 2.06 | |
| Nothing/no one | 0.91 | 0.58 – 1.42 | 0.96 | 0.52 – 1.76 | |
| Work fear-avoidance52 ⋄⋄ (ref= <3, very low) | 0.27 | ||||
| Low-moderate (>3 – <5) | 1.71 | 0.93 – 3.16 | 1.00 | 0.47 – 2.16 | |
| High (5 – 6) | 3.85 | 2.21 – 6.70 | 1.47 | 0.71 – 3.04 | |
| SF-36 v2 Mental Health35 (ref=>50) | 0.26 | ||||
| 41 – 50 | 3.27 | 2.05 – 5.20 | 1.31 | 0.72 – 2.40 | |
| ≤ 40 | 3.53 | 2.29 – 5.45 | 0.87 | 0.48 – 1.58 | |
Each baseline variable included in this table was associated (P < 0.10) in bivariate analyses with back surgery by three years after occupational back injury
ref = reference group
^
adjusted for age and gender, except for age and gender
^^
adjusted for all other variables in the multivariate model