| Methods |
Design: six group parallel trial
Purpose: examine the effect of psychological treatments on chronic insomnia |
| Participants |
Patients: out‐patients suffering from chronic sleep‐onset insomnia
Baseline comparability: yes (age, sex, duration of insomnia) |
| Interventions |
Placebo: imaginary belief treatment: neutral images paired with bed time activities.
Untreated: waiting list
Experimental:
‐relaxation therapy
‐stimulus control
‐paradoxical intervention
‐tailored therapy condition (reported in another publication)
(Co‐intervention: hypnotics, fixed ordination and withdrawal scheme, compliance NS) |
| Outcomes |
Sleep latency (min)
Sleep quality |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Low risk |
'predetermined list of random numbers' |
| Allocation concealment? |
Unclear risk |
NS |
| Blinding?
Treatment provider |
High risk |
Not described as double‐blind (placebo/psychological intervention) |
| Blinding?
Outcome assessor |
Unclear risk |
Not relevant as patient reported outcome |
| Incomplete outcome data addressed?
All outcomes |
High risk |
Drop‐out > 15% or NS |
| Free of selective reporting? |
Unclear risk |
No protocol available |
| Free of other bias? |
Low risk |
|
| No signs of variance inequality or skewness? |
High risk |
Either variance inequality (F‐test statistically significant) or skewness (1.64 standard deviations exceeds the mean) |
| Trial size > 49? |
High risk |
N = 27 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Trial size < 49 |
