Table 3.
Multivariable linear regression model
| Variable | Coefficient | 95% CI | p-value |
|---|---|---|---|
| Intercept | 42.9 | 33.4 to 52.4 | < 0.001 |
| Depression | 8.7 | 4.5 to 12.8 | < 0.001 |
| Nocturnal pain | 4.5 | 0.9 to 8.0 | 0.013 |
| Need for painkillers | 5.3 | 0.5 to 10.1 | 0.032 |
| PK dose > 1 a day | 0.0 | – 3.3 to 3.3 | 0.99 |
| Disease duration > 2 years* | 3.3 | 0.2–6.4 | 0.036 |
| Number of comorbidities > 1** | – 1.6 | – 4.7 to 1.5 | 0.31 |
| Hypercholesterolemia | – 0.3 | – 4.6 to 4.0 | 0.88 |
| Moring stiffness > 30 min | 2.0 | – 1.2 to 5.2 | 0.23 |
| Social interactions | – 0.6 | –1.4 to 0.1 | 0.1 |
| Mood | – 0.9 | –1.8 to – 0.1 | 0.031 |
| Physical activity | – 0.6 | –1.9 to 0.7 | 0.39 |
| CPGS grade | 2.8 | 1.2 to 4.4 | < 0.001 |
F(12) = 9.8, p-value < 0.001, R2 = 40%, R2-adjusted = 37%, Skew=-0.11, Kurtosis = 2.94
*The variable was dichotomized based on the median value to enhance the generalizability of the models
**Depression and hypercholesterolemia were excluded from the total number of comorbidities to provide independence of variables, and then were dichotomized based on the median value