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. 2010 Dec 15;6(6):572–580.

Table 2.

Polysomnography and self-report findings for key study outcomes

Parameter Ramelteon (SD), n = 8
Placebo (SD), n = 13
Mean Difference (SD, 95% CI p-value Effect size95% CI
Pre Post Pre Post
    Polysomnography
        Sleep latency (minutes) 20.4 (23.2) 9.7 (10.3) 16.6 (17.5) 34.4 (30.7) 28.5 (16.2, 8.5 to 48.6) 0.008 1.35 (0.32, 2.25)1
        Sleep efficiency (percent) 72.5 (24.5) 78.6 (10.5) 70.3 (17.6) 72.8 (16.9) −3.6 (22.5, −24.7 to 17.6) 0.7 −0.16 (−1.04, 0.73)1
        AHI (events/h) 13.9 (7.5) 16.0 (11.6) 10.9 (12.9) 13.5 (12.1) 0.5 (12.9, −11.6 to 12.6) 0.9 0.04 (−0.84, 0.92)1
    Self-report
        Sleep latency (minutes) 35.2 (43.9) 31.5 (24.0) 23.8 (15.0) 18.8 (11.0) −1.3 (19.3, −21.4 to 18.7) 0.9 −0.07 (-0.94, 0.82)2
        Sleep efficiency (percent) 72.5 (22.6) 68.5 (24.1) 71.6 (17.0) 76.8 (14.9) 9.2 (19.6, −9.6 to 27.9) 0.3 0.5 (−0.44, 1.35)2

The Mean Difference column compares the pre-study drug to post-study drug change between the ramelteon and placebo arms. It is the difference between the change score for the ramelteon arm and the placebo arm. Mean Difference = ramelteon change (i.e., pre-ramelteon – post-ramelteon) – placebo change (i.e., pre-placebo – post-placebo). Effect size interpretation: The direction of the effect size estimate can represent an improvement or worsening in the ramelteon arm relative to the placebo arm depending upon the nature of the variable. To facilitate interpretation, a (1) indicates improvement in the ramelteon arm relative to the placebo arm, and a (2) indicates improvement in the placebo arm relative to the ramelteon arm.