Table 3.
Results of the regression model estimating day-level total pain score (N=1009)
| Conditional random effects | Variance (95% CI) |
| Participant | 1.09 (0.98 to 1.21) |
| Conditional fixed effects | Rate ratio (95% CI) | Log odds (SE) | z-score |
| Intercept | 4.26*** (3.26 to 5.56) | 1.45*** (0.13) | 10.82 |
| Menstrual status | 1.29*** (1.25 to 1.32) | 0.25*** (0.01) | 20.31 |
| Previous-day pain | 1.02*** (1.02 to 1.03) | 0.02*** (0.00) | 29.69 |
| Body mass index (BMI) | 1.01* (1.00 to 1.02) | 0.01 (0.00) | 2.02 |
| Mean weekly exercise frequency | 0.93* (0.89 to 0.97) | −0.06** (0.02) | −2.96 |
| Previous-day exercise | 1.10* (1.05 to 1.15) | 0.09**(0.15) | 3.88 |
| Some college education level | 0.87 (0.83 to 1.56) | 0.13 (0.15) | 0.86 |
| College or higher education level | 0.93 (0.66 to 1.16) | −0.13 (0.14) | −0.92 |
| Mean weekly exercise frequency×previous-day exercise | 0.96** (0.95 to 0.98) | −0.03** (0.01) | −3.37 |
| Zero inflation terms | Rate ratio (95% CI) | Log odds (SE) | z-score |
| Intercept | 0.17 (0.16 to 0.18) | −1.73***(0.02) | −62.96 |
| Same-day exercise | 5.34 (5.01 to 5.68) | 1.67*** (0.03) | 52.53 |
Previous-day pain and BMI were sample mean centred. BMI and education level were kept as covariates in the model based on their significant associations with mean day-level pain scores (Pearson’s r=0.15 for BMI and Kruskal-Wallis χ2=18.061 for education level, p<0.001).
*P<0.05, **p<0.001, ***p<0.0001.