Table 4.
Estimated increase in questionnaire score level (95%confidence interval) by treatment group, by unit increase in baseline score and point of measurement using a linear mixed model
| RAND-36 | QoR-40 | RI-10 | |
|---|---|---|---|
| Treatment groupa | |||
| LH | 142 (46; 236) | 9 (−3; 21) | 7 (0; 14) |
| AH | 0 (reference) | 0 (reference) | 0 (reference) |
| Baseline effect | |||
| per 10 unitsb | 7 (4; 11) | 5 (1; 9) | n.a. |
| Time after surgery | |||
| 1 day | n.a. | 0 (reference) | n.a. |
| 2 days | n.a. | 4 (−3; 12) | n.a. |
| 3 days | n.a. | 4 (−4; 11) | n.a. |
| 1 week | 0 (reference) | 13 (6; 20) | 0 (reference) |
| 2 weeks | −8 (−64; 47) | 26 (18; 33) | 0 (−3; 2) |
| 4 weeks | 49 (−6; 105) | n.a. | 4 (1; 6) |
| 6 weeks | 130 (74; 185) | n.a. | 6 (4; 9) |
| 12 weeks | 122 (67; 178) | n.a. | 8 (5; 11) |
Example: On average, the estimated level of the total RAND-36 score in the LH group was 142 units higher as compared with the AH group, at each timepoint from 2 to 12 weeks after surgery. The estimated increase per 10 units higher level in the total RAND-36 score at baseline between two patients was 7 units. This was independent of both timepoint and treatment group. Furthermore, the estimated increase in the total RAND-36 score at 12 weeks after surgery, compared to 1 week after surgery, was 122 units in both groups
Because the data fit very well to the parallel-line model the differences over time after surgery is estimated to be identical in both groups (see also Fig. 2a, b and c)
LH laparoscopic hysterectomy, AH abdominal hysterectomy, RAND-36 RAND 36-Item Short Form Health Survey, QoR-40 Quality of Recovery-40, RI-10 Recovery Index-10, n.a. not applicable
aDifference between groups after correction for baseline differences
bThe baseline effect is the increase in postoperative score per 10 units increase at baseline