Table 4.
Change in quality-of-life scores from the end of SDP to the end of DBRWP (efficacy population)
| Score | Placebo (n = 65) | LXB (n = 69) |
|---|---|---|
| SF-36 physical component summary | ||
| End of SDP | ||
| Median (Q1, Q3) | 51.5 (44.0, 57.4) | 53.9 (46.9, 58.3)* |
| End of DBRWP | ||
| Median (Q1, Q3) | 50.7 (43.2, 55.8) | 53.7 (47.2, 58.6) |
| Change from SDP to DBRWP | ||
| Median (Q1, Q3) | −1.9 (−3.5, 1.7) | 0.0 (−2.1, 2.4)* |
| Location shift (95% CI)† | 1.4 (−0.1, 2.8) | |
| p value‡ | 0.0174 | |
| SF-36 Mental Component Summary | ||
| End of SDP | ||
| Mean (SD) | 48.1 (9.9) | 45.2 (12.2)* |
| End of DBRWP | ||
| Mean (SD) | 46.0 (9.9) | 46.8 (11.3) |
| Change from SDP to DBRWP | ||
| Mean (SD) | −2.0 (7.8) | 1.3 (6.6) |
| LS mean (SE)‡ | −2.2 (0.9) | 0.4 (0.9) |
| LS mean difference (SE; 95% CI)‡ | 2.5 (1.2; 0.2, 4.8) | |
| p value‡ | 0.0331 | |
| EQ-5D-5L Crosswalk Index | ||
| End of SDP | ||
| Median (Q1, Q3) | 0.89 (0.80, 1.00) | 0.87 (0.80, 1.00)§ |
| End of DBRWP | ||
| Median (Q1, Q3) | 0.88 (0.81, 1.00) | 0.91 (0.83, 1.00) |
| Change from SDP to DBRWP | ||
| Median (Q1, Q3) | 0.00 (−0.05, 0.03) | 0.00 (−0.01, 0.03)§ |
| Location shift (95% CI)† | 0.000 (0.000, 0.014) | |
| p value|| | 0.3918 | |
| EQ-5D-5L Visual Analog Scale | ||
| End of SDP | ||
| Median (Q1, Q3) | 75.0 (70.0, 90.0) | 80.0 (70.0, 90.0) |
| End of DBRWP | ||
| Median (Q1, Q3) | 75.0 (60.0, 85.0) | 80.0 (70.0, 90.0) |
| Change from SDP to DBRWP | ||
| Median (Q1, Q3) | −5.0 (−10.0, 5.0) | 0.0 (0.0, 5.0) |
| Location shift (95% CI)† | 5.0 (0.0, 7.0) | |
| p value|| | 0.0056 |
ANCOVA, analysis of covariance; CI, confidence interval; DBRWP, double-blind randomized withdrawal period; EQ-5D-5L, EuroQoL EQ-5D-5L; LS, least squares; LXB, lower-sodium oxybate; Q1, first quartile; Q3, third quartile; SD, standard deviation; SDP, stable-dose period; SE, standard error; SF-36, 36-Item Short Form Health Survey Version 2.
*n = 67.
†The location shift between 2 treatment groups and 95% asymptotic CI are from Hodges–Lehmann estimate.
‡The LS means, SEs, LS mean difference, 95% CI, and p value were obtained from an ANCOVA model including the change in the scale-normalized score/overall component score from the end of SDP to the end of DBRWP as response variable; prior treatment group and study treatment group as fixed effects; and scale-normalized score/overall component score at the end of SDP as covariate.
§ n = 68.
||The p value was obtained from a rank-based ANCOVA model including the change in the crosswalk index score/visual analog scale value from the end of SDP to the end of DBRWP as response variable; prior treatment group and study treatment group as fixed effects; and crosswalk index score/visual analog scale value at the end of SDP as covariate.