A WASO sub-group analysis of a 6-month study of eszopiclone 3mg
Sleep Medicine, 06/29/2012
Krystal AD et al. – As illustrated in this analysis, a significant proportion of chronic insomnia patients in efficacy trials that select on the basis of sleep onset latency and total sleep time criteria may have normative–range wake time after sleep onset (WASO). However, even in the subgroup with minimal WASO there was a significant sleep maintenance effect. The absence of any sleep maintenance effect in a drug trial may reflect the inclusion of relatively many insomnia patients with no baseline WASO abnormality. However, treatments with therapeutic effects on sleep maintenance, can still demonstrate improvement in sleep maintenance, even in a population not selected for this type of sleep problem, if adequately powered.Methods
- Patients diagnosed with chronic primary insomnia were randomized to eszopiclone 3mg (n=593) or placebo (n=195) nightly for sixmonths.
- The present analyses of this study consisted of: (1) determination of the distribution of baseline WASO; (2) continuous analysis of the relationship between baseline WASO severity and drug–placebo difference at month 1 and 6; and (3) categorical efficacy analyses of subgroups delimited by the following WASO thresholds: 0, 30, 45, 60, and 90min.
- The baseline WASO distribution was: 30=32.2%; >0 to 45=41.5%; >30 to 90=33.0%; >45 to 90=23.7%; >90=22.6%.
- A relationship between greater baseline WASO severity and a significantly greater drug–placebo difference in efficacy for WASO was evident in both continuous and categorical analyses.
- Eszopiclone was found to have significant sleep maintenance efficacy at each time point across the entire range of WASO severity studied.