Table 3.
Studies reporting explained variance from regressions. Predictive instruments and models used for function-related outcomes at different time-points. Models predict restricted function
| Study | Predictive factors/instruments | R2 | P | Δ R2 | ΔP | β | Outcome |
|---|---|---|---|---|---|---|---|
| Dionne 1997 [10] Patients with 1-month Roland-Morris score >0 in the training sample (N at follow up: 408) |
SCL-90-R Somatization | 0.175 | Modified Roland-Morris at two years | ||||
| SCL-90-R Depression | 0.218 | ||||||
| 1-month Roland-Morris | 0.262 | ||||||
| Number of pain days in the past 6 months (N=395) | 0.283 | ||||||
| Dionne 1997 [10] total sample N at follow up: 1213 |
α | −0.003203 | Modified Roland-Morris at two years | ||||
| SCL-90-R Somatization | 0.040177 | ||||||
| SCL-90-R Depression | 0.093217 | ||||||
| 1-month Roland-Morris | 0.256079 | ||||||
| Number of pain days in the past 6 months | 0.000581 | ||||||
| Epping-Jordan 1998 [13] N at follow up: 78 |
2-month disability | 0.45 / 0.32 | 0.000/0.000 | 0.5/0.42 | 6/12 months disability (SIP) | ||
| Income (−) | 0.48/0.38 | 0.174/0.085 | −0.2/−0.7 | ||||
| Ethnicity (minority ethnicity) (− for 12 months) | 0.11/−0.2 | ||||||
| Age (− for 6 months) | −0.9 / 0.8 | ||||||
| 2-month pain intensity (− for 12 months) | 0.51/0.40 | 0.148/0.348 | 0.07/−0.6 | ||||
| 2 month depression | 0.20/0.16 | ||||||
| Hansson 2000 [14], Denmark N at follow up: 494 |
Age | 0.000 | Back function (Hannover ADL) 12 months (multiple regression) | ||||
| Gender (female) | 0.000 | ||||||
| Physical therapy | 0.010 | ||||||
| Hansson 2000 [14], Germany N at follow up: 295 |
Age | 0.000 | Back function (Hannover ADL) 12 months (multiple regression) | ||||
| Psychological demand | 0.007 | ||||||
| Heat and cold (treatment) | 0.039 | ||||||
| Hansson 2000 [14], Israel N at follow up: 289 |
Age | 0.000 | Back function (Hannover ADL) 12 months (multiple regression) | ||||
| Hansson 2000 [14], Netherlands N at follow up: 392 |
Age | 0.000 | Back function (Hannover ADL) 12 months (multiple regression) | ||||
| Gender (female) | 0.000 | ||||||
| Decision latitude (control) (-) | 0.035 | ||||||
| Hansson 2000 [14], Sweden N at follow up: 455 |
Age | 0.000 | Back function (Hannover ADL) 12 months (multiple regression) | ||||
| Gender (female) | 0.013 | ||||||
| Psychological demand | 0.024 | ||||||
| Surgery during first year | 0.017 | ||||||
| Hansson 2000 [14], USA N at follow up: 413 |
Age | 0.000 | Back function (Hannover ADL) 12 months (multiple regression) | ||||
| Gender (female) | 0.002 | ||||||
| Treatment received before sick report | 0.043 | ||||||
| Psychological demands | 0.004 | ||||||
| Physical job demands | 0.018 | ||||||
| Back-School program | 0.008 | ||||||
| Klenerman 1995 [23] N at follow up 162 |
Physical (side flexion, neurological deficit, sagittal extension, nerve root thethering sagittal flexion and ability to sit) | 0.206 | 0.0002 | Pain and disability at 12 months | |||
| Psychosocial (inappropriate signs and symptoms, MSPQ, Roland and Morris disability, Zung depression, pain, Oswestry disability index) | 0.369 | 0.0001 | |||||
| Fear-avoidance | 0.226 | 0.0001 | |||||
| All | 0.488 | 0.0001 | |||||
| Truchon, 2005 [36] N at follow up: 321 |
Age (−), gender (female), education (−), disability | 0.26 | 0.26 | <0.01 | Roland Morris at 6 months | ||
| CPCI scales: guarding (+), resting (−), asking for assistance, relaxation, task persistence, exercise/stretch (−), coping self-statements, seeking social support | 0.35 | 0.09 | 0.05 | ||||
| Catastrophizing (CSQ) | 0.36 | 0.00 | 0.51 | ||||
| Williams 1998 [47] Same population as [13] and N at follow up: 82 |
Disability at 2 months | 0.32 | 0.37 | Disability at 6 months | |||
| Ethnicity (Minority) | 0.35 | −0.11 | |||||
| Orthopedic impairment | 0.41 | 0.29 | |||||
| Job satisfaction (−) | 0.48 | −0.28 |
Negative signs in the parentheses besides the predictors indicate that the factor is negatively related with restricted function, e.g. income (−) means that less income is related with more restricted function. If no sign is besides the predictors this means that this factor is positively related with persistent restriction in function, e.g. older age is related with more restricted function, or heat or cold therapies are related with restricted function. R2: proportion of the variance explained by the model. P: P-value, Δ R2: additional variance explained when the given factor is added to the model, and ΔP its corresponding P-value. β: regression coefficients
SCL-90 Somatization: Symptoms Checklist-90 Revised, Somatization subscale. SCL-90 R Depression: Symptoms Checklist-90 Revised, Depression subscale
Roland Morris: disability questionnaire with 24 items, higher scores indicates more restriction in functioning
Decision latitude: decision possibilities and control in job
Orthopaedic impairment: Waddel impairment index for measuring the severity of orthopaedic disease in back disorders. Score from 0 to 50 (more impairment)