Table 3.
Bivariate and multivariate associations with fatigue. Separate multivariate analyses for RA-specific and other risk factors
| Bivariate | Multivariate | Bivariate | Multivariate | |||
|---|---|---|---|---|---|---|
| β (p) | β (p) | β (p) | β (p) | |||
| Demographic | ||||||
| Age | −0.01 (.37) | --- | ||||
| Female | 0.14 (.75) | --- | ||||
| White, non-Hispanic | −0.46 (.21) | --- | ||||
| RA-specific risk factors | Other risk factors* | |||||
| Duration of RA | −0.01 (.58) | --- | PSQI total score | 0.27 (<.0001) | 0.15 (.0006) | |
| RA Disease Activity Index (RADAI) | 0.65 (<.0001) | 0.52 (<.0001) | PHQ score | 0.24 (<.0001) | 0.12 (.001) | |
| Glucocorticoid use | 0.17 (.59) | --- | Physical inactivity† | 1.17 (.0002) | 0.31 (.26) | |
| Prednisone dose, mg | 0.09 (.07) | −0.03 (.57) | Obesity § | 1.29 (<.0001) | 0.77 (.01) | |
| Biologic use | −0.26 (.43) | --- | Lean mass / fat mass | −0.49 (.0009) | −0.12 (.38) | |
| C-reactive protein (log value) | 1.09 (.004) | 0.12 (.74) | Hip flexion strength | −0.56 (.005) | −0.07 (.72) | |
| Functional limitations, HAQ | 1.35 (<.0001) | 0.54 (0.04) | Knee extension strength | −0.07 (.40) | --- | |
| Resting heart rate | 0.03 (.05) | --- | ||||
| Smoking, ever | 0.95(.003) | --- | ||||
| Smoking, now | 2.31 (<.0001) | 0.98 (.06) | ||||
| Model F value (df) | 16.43 (4) | Model F value (df) | 16.96 (7) | |||
| Model R2 | 0.35 | Model R2 | 0.50 | |||
| Model adjusted R2 | 0.33 | Model adjusted R2 | 0.47 |
*
In the initial multivariate model, resting heart rate exhibited multicollinearity and was removed
†
Defined as <150 minutes of moderate or vigorous activity in responses to International Physical Activity Questionnaire (IPAQ)
Women: BMI ≥ 26.1; men BMI ≥ 24.7 [31]