Table 7.
Multivariable linear regression analysis of factors associated with the PROMIS Physical Function score.
| Variables | Regression coefficient |
Standard error | P value | Partial R2 |
|---|---|---|---|---|
| (95% Confidence Interval) | ||||
| Gender | ||||
| Women | reference value | |||
| Men | 1.6 (−0.69 to 3.9) | 1.2 | 0.17 | 0.017 |
| Insurance | ||||
| Public or no insurance | reference value | |||
| Private | 1.1 (−1.3 to 3.4) | 1.2 | 0.38 | 0.0071 |
| Work status* | ||||
| Employed | reference value | |||
| Retired | −2.8 (−5.5 to −0.13) | 1.3 | 0.040 | 0.038 |
| Other | −4.3 (−7.3 to −1.4) | 1.5 | 0.005 | 0.070 |
| Duration of symptoms | −0.0044 (−0.024 to 0.015) | 0.0097 | 0.66 | 0.0018 |
| PCS-4† | −1.1 (−1.5 to −0.59) | 0.24 | <0.001 | 0.15 |
| Kellgren-Lawrence grade | 0.099 (−0.84 to 1.0) | 0.48 | 0.84 | 0.00039 |
Bold indicates statistical significance, P < 0.05. PCS-4= Pain Catastrophizing Scale 4-item. *The variables ‘Annual household income’ and ‘Education’ were omitted because they were associated with ‘Work status'. † The GAD-2, PHQ-2, PSEQ-2, and PROMIS Physical Function were omitted due to collinearity with PCS-4 (Spearman ρ > 0.40).