Table 3.
Conditional growth model for pain intensity and ASES score with effects for type of surgery (mean baseline) and interactions of type of surgery*time (rate of recovery)
| Pain intensity | ASES score | |||||
| Estimate (95% CI) | Step 1 p value | Step 2 p value | Estimate (95% CI) | Step 1 p value | Step 2 p value | |
| Step 1: Variation in mean baseline scores (main effects model) | ||||||
| Time | -0.22 (-0.24 to -0.21)a | < 0.01 | < 0.01b | 2.9 (2.8 to 3.0)a | < 0.01 | < 0.01b |
| Type of surgery (mean baseline) | ||||||
| TSA | Reference value | Reference value | ||||
| rTSA | -0.20 (-0.38 to -0.027)a | 0.02 | 0.18b | 0.62 (-0.66 to 1.9)a | 0.34 | 0.34b |
| Step 2: Variations in rate of recovery (interaction effects model) | ||||||
| Type of surgery*time (rate of recovery) | ||||||
| TSA | Reference value | Reference value | ||||
| rTSA | -0.0050 (-0.035 to 0.025) | 0.74 | -0.044 (-0.26 to 0.17) | 0.69 | ||
Step 1model summary: pain intensity: r2 = 0.25, AIC 16958, BIC 16977; ASES: r2 = 0.51, AIC 32003, BIC 32022. Step 2 model summary: pain intensity: r2 = 0.25, AIC 16960, BIC 16985; ASES: r2 = 0.51, AIC 32005, BIC 32030.
aThese estimates are derived from the model in Step 1, where we only accounted for the effect of type of surgery on the mean baseline score.
bThese p values are based on the model in which we accounted for the effect of type of surgery on rate of recovery (Step 2), where estimates for the mean baseline score are less accurate than in Step 1 and are therefore not presented. Variables are deemed clinically relevant when p values in both steps are significant.