Table 2.
Mixed Model Results including mean estimate under both treatments, the difference (mexiletine minus placebo) with 95% confidence interval, Effect Size and Significance Level from the Wald Test.
| Endpoint – Period (No. of Participants) | Mean Mexiletine Treatment (95% Confidence Interval)* | Mean Placebo Treatment (95% Confidence Interval)* | Treatment Effect Estimate △ (95% Confidence Interval) | Effect Size◆ | P-value† |
|---|---|---|---|---|---|
| IV: Stiffness – First (57)‡ | 2.53 (1.80, 3.17) | 4.21 (3.40, 5.20) | −1.68 (−2.66, −0.706) | −1.36 | <0.001 |
| IVR: Stiffness - Second (57)‡ | 1.60 (1.04, 2.20) | 5.27 (4.44, 6.27) | −3.68 (−3.85, −0.139) | −2.97 | 0.04 |
| IVR: Pain – Overall (48)§ | 1.54 (0.924, 2.13) | 3.17 (2.43, 3.93) | −1.63 (−2.00, −1.26) | −1.36 | <0.001 |
| IVR: Weakness – Overall (44) § | 1.96 (1.42, 2.63) | 3.22 (2.52, 3.98) | −1.26 (−1.67, −0.861) | −0.994 | <0.001 |
| IVR: Tiredness – Overall (49) § | 2.9 (2.12, 3.68) | 3.82 (3.03, 4.53) | −0.918 (−1.30, −0.532) | −0.709 | <0.001 |
| Short Exercise – Overall (% baseline; 56) | 83.1 (77.5, 88.4) | 78.6 (71.9, 84.7) | 4.54 (−0.680, 9.75) | 0.347 | 0.09 |
| Prolonged Exercise – Overall (% baseline; 56) | 81.8 (76.8, 87.0) | 80.1 (74.7, 86.4) | 1.69 (−3.34, 6.73) | 0.134 | 0.50 |
| Needle EMG: RADM – Overall (56) | 2.05 (1.75, 2.33) | 2.62 (2.39, 2.86) | −0.568 (−0.812, −0.325) | −0.947 | <0.001 |
| Needle EMG: RTA – Overall (56) | 2.07 (1.73, 2.37) | 2.54 (2.28, 2.76) | −0.464 (−0.675, −0.254) | −0.900 | <0.001 |
| SF36: Physical Function – Overall (57) | 42.8 (40.1, 46.1) | 37.8 (34.9, 41.3) | 5.00 (2.81, 7.20) | .904 | <0.001 |
| SF36: Role Physical – Overall (57) | 46.5 (43.6, 49.2) | 39.2 (35.7, 42.6) | 7.23 (4.55, 9.92) | 1.07 | <0.001 |
| SF36: Bodily Pain – Overall (57) | 49.8 (46.4, 52.6) | 42.0 (38.6, 45.5) | 7.78 (5.08, 10.5) | 1.14 | <0.001 |
| SF36: General Health – Overall (57) | 45.5 (41.9, 48.7) | 44.5 (41, 47.7) | 0.977 (−0.659, 2.61) | 0.240 | 0.24 |
| SF36: Vitality – First (57) | 45.5 (41.1, 49.6) | 43.7 (39.7,48.1) | 1.76 (−4.34, 7.85) | 0.211 | 0.57 |
| SF36: Vitality – Second (57) | 51.9 (48.1, 55.5) | 40.0 (35.1, 45.0) | 11.9 (−0.307, 20.5) | 1.43 | 0.06 |
| SF36: Social Function – Overall (57) | 47.1 (44.4, 49.8) | 41.9 (38.5, 44.9) | 5.27 (2.69, 7.85) | 0.809 | <0.001 |
| SF36: Role Emotional – First (57) | 46.2 (42.0, 50.3) | 45.5 (41.2, 49.4) | 0.764 (−5.68, 7.21) | 0.102 | 0.81 |
| SF36: Role Emotional – Second (57) | 49.9 (46.2, 53.1) | 39.1 (33.5, 45.0) | 10.8 (−1.51, 21.6) | 1.45 | 0.09 |
| SF36: Mental Health – First (57) | 47.3 (43.6, 51.0) | 47.3 (43.7, 50.6) | 0.016 (−5.24,5.27) | 0.00258 | 0.99 |
| SF36: Mental Health – Second (57) | 53.3 (50.2, 56.2) | 44.4 (39.8, 48.7) | 8.84 (−0.572, 18.2) | 1.42 | 0.07 |
| SF36: Physical Composite – Overall (57) | 44.8 (41.9, 47.4) | 39.2 (35.9, 41.9) | 5.58 (3.44, 7.72) | 1.04 | <0.001 |
| SF36: Mental Composite – First (57) | 47.4 (44.0, 50.2) | 47.7 (44.2, 51.3) | −0.351 (−5.87, 5.17) | −0.0539 | 0.90 |
| SF36: Mental Composite – Second (57) | 53.1 (50.3, 55.8) | 42.7 (36.8, 48.3) | 10.4 (0.941, 20.6) | 1.60 | 0.03 |
| INQoL: Weakness – Overall (35) | 45.7 (37.7, 52.6) | 49.3 (41.7, 57.3) | −3.56 (−9.54, 2.43) | −0.290 | 0.24 |
| INQoL: Muscle Locking – Overall (43) | 40.0 (33.1, 46.7) | 53.8 (46.4, 61.1) | −13.7 (−20.4, −7.03) | −0.888 | <0.001 |
| INQoL: Pain – Overall (32) | 39.9 (30.6, 49.0) | 48.2 (39.2, 57.1) | −8.32 (−13.8, −2.87) | −0.782 | 0.004 |
| INQoL: Fatigue – Overall (35) | 48.4 (40.9, 56.6) | 58.3 (50.6, 66.0) | −9.96 (−17.0, −2.93) | −0.678 | 0.007 |
| INQoL: Activity – Overall (51) | 34.2 (26.7, 43.0) | 47.1 (40.1, 55.5) | −12.9 (−18.3, −7.43) | −0.950 | <0.001 |
| INQoL: Independence – Overall (51) | 17.8 (12.3, 23.3) | 22.5 (17.2, 28.1) | −4.74 (−8.14, −1.35) | −0.561 | 0.007 |
| INQoL: Social Relations – Overall (51) | 18.9 (13.5, 24.5) | 25.9 (18.0, 35.2) | −7.02 (−13.4, −0.671) | −0.440 | 0.03 |
| INQoL - Emotions – Overall (51) | 27.7 (22.0, 34.4) | 33.8 (27.1, 41.5) | −6.13 (−10.1, −2.15) | −0.619 | 0.003 |
| INQoL: Body Image – Overall (51) | 24.2 (17.3, 31.0) | 29.4 (22.0, 36.5) | −5.27 (−10.4, −0.105) | −0.408 | 0.05 |
| INQoL: QOL – Overall (51) | 14.0 (11.6, 16.5) | 16.7 (14.0, 19.4) | −2.69 (−4.07, −1.30) | −0.780 | <0.001 |
| INQoL: Perceived Rx Effect – Overall (51) | 36.6 (27.1, 45.8) | 21.7 (12.7, 31.1) | 14.9 (7.43, 22.3) | 0.797 | <0.001 |
| INQoL: Expected Rx Effect – Overall (51) | 36.1 (26.9, 47.0) | 23.1 (14.5, 33.6) | 13.0 (4.18, 21.8) | 0.585 | 0.005 |
| Clinical Assessment: Eye Closure – Overall (seconds; 57) € | 0.161 (0.0704, 0.314) | 0.474 (0.261, 0.871) | −0.313 (−0.602, −0.149) | −0.888 | <0.001 |
| Clinical Assessment: Hand Grip – Overall (seconds; 57) ¤ | 0.164 (0.0858, 0.294) | 0.494 (0.281, 0.872) | −0.330 −0.633, −0.142) | −0.748 | <0.001 |
| QMA Hand Grip – Overall (seconds; 54) ¤ | 0.321 (0.274, 0.370) | 0.429 (0.365, 0.517) | −0.109 (−0.177, −0.0560) | −0.518 | <0.001 |
The confidence intervals for the predicted treatment group means are boot strap confidence intervals. These confidence intervals reflect the precision of the estimates without exploiting the correlated nature of the data unlike the treatment effect confidence intervals.
All treatment effect estimates and confidence intervals are extracted from mexiletine treatment variable of the fitted mixed model.
The effect size is the treatment effect estimate divided by the within-participant standard deviation.
Significance level of the Wald Test associated with the Mexiletine Effect from the additive model, when no carryover effect was detected. When a carryover effect was detected, the significance level associated with the additive portion of the Mexiletine Effect (labeled period 1) followed in the next row by the level associated with the interaction of Mexiletine and period 2 (labeled period 2). The exceptions are to two needle EMG tests where the Wilcoxon test was substituted because of the outcome is not a continuous variable and therefore normality of the residuals is not satisfied.
Primary outcome: 52 participants contributed to the both periods while 5 only contributed to period 1.
Only participants that experienced this symptom were included.
The treatment-specific group mean is a geometric mean estimate. The treatment effect estimate is the difference between the treatment-specific group means.
The treatment-specific group mean is a geometric-like mean estimate using the log(t + 0.1) “normalizing” transformation. The treatment effect estimate is the difference between the treatment-specific group means.