Table 3.
Prognostic factors at baseline for activity limitation at the later 2-year follow-up using the Roland Morris disability questionnaire (RMDQ) at 2-year follow-up (n=120)
| Spearman’s rank correlation Correlation with RMDQ at 2 years |
Forward stepwise multivariate linear regression* Independent variables p<0.20 entered in the model, adjusted for age R2=0.54 for the overall model |
||||
| N | r | p Value | β (95% CI) | p Value | |
| Age, years | 120 | 0.067 | 0.47 | −0.0048 (−0.019 to 0.010) | 0.51 |
| Lifestyle behavioural factors | |||||
| Body mass index (kg/m2) | 119 | 0.21 | 0.021 | ||
| Smoker (n=72)—non-smoker (n=48) | 120 | 0.14 | 0.14 | ||
| AUDIT-C (0–12)† | 118 | −0.23 | 0.011 | ||
| Sleep quantity (1–4)‡ | 120 | −0.34 | 0.00014 | ||
| Sleep quality (1–4)§ | 118 | −0.43 | <0.0001 | ||
| SCI-93¶ | 120 | 0.48 | <0.0001 | 0.0091 (0.0023 to 0.016) | 0.0088 |
| LTPAI (hours per week)** | 119 | −0.11 | 0.24 | ||
| Body function | |||||
| Pain localisations (0–18)†† | 120 | 0.36 | 0.000052 | ||
| Pain intensity 10 mm (VAS 0–100)‡‡ | 120 | 0.20 | 0.027 | ||
| Fatigue 10 mm (VAS 0–100)‡‡ | 120 | 0.24 | 0.0078 | ||
| 6MWT, 100 m | 118 | −0.41 | <0.0001 | −0.23 (−0.42 to −0.036) | 0.020 |
| Hand grip strength 50 (N) | 120 | −0.17 | 0.070 | ||
| HADS-A (0–21) §§ | 120 | 0.16 | 0.089 | ||
| HADS-D (0–21)§§ | 120 | 0.37 | 0.000025 | ||
| Activity | |||||
| RMDQ at baseline (0–24)¶¶ | 118 | 0.71 | <0.0001 | 0.10 (0.068 to 0.14) | <0.0001 |
| Participation | |||||
| Work ability (n=95)—no work ability (n=25) | 120 | −0.37 | 0.000026 | ||
| Environmental factors | |||||
| Private social support (4–20)*** | 120 | −0.29 | 0.0013 | ||
| Health-related quality of life | |||||
| PCS (0–100)††† | 119 | −0.42 | <0.0001 | ||
| MCS (0–100)††† | 119 | −0.28 | 0.0022 | ||
*RMDQ score was transformed to ranked normal score of RMDQ using Blom’s formula. The final model was adjusted for age using standard (Enter) multivariate linear regression.
†The AUDIT-C, three items. Higher scores reflect higher alcohol consumption (0–12).
‡One item: ‘Do you think you get enough sleep?’. Higher scores indicate better sleep (1–4).
§One item: ‘On the whole, how do you think you sleep?’. Higher scores indicate better sleep (1–4).
¶Higher scores indicate more severe clinical stress symptoms (0–140).
**The LTPAI assesses the total hours of physical activity in leisure time during a typical week.
††Self-reported pain locations registered by a figure with predefined body locations (0–18).
‡‡Perceived pain intensity, fatigue over the last week rated on a VAS (0–100). Higher values indicate more pain, fatigue.
§§Higher scores indicate more anxiety (0–21) and depression (0–21).
¶¶RMDQ indicates disability related to low back pain (0–24) at baseline. Higher scores indicate more severe disability.
***Medical Outcome Study Social Support Survey (four-item scale) reflects private social support ranging from 1 to 5. Higher scores reflect more perceived support (4–20).
†††SF-36. The PCS score (0–100) and MCS score (0–100).
6MWT, 6 min walk test; AUDIT-C, Alcohol Use Disorders Identification Test; HADS-A and HADS-D, Hospital Anxiety and Depression Scale; LTPAI, leisure time physical activity instrument; MCS, mental component summary; PCS, physical component summary; SCI-93, Stress and Crisis Inventory; SF-36, short-form health survey; VAS, visual analogue scale.