| Methods |
Design: five group parallel trial
Purpose: to demonstrate a) therapist bias and b) that a double blind design is feasible in psychotherapy |
| Participants |
Patients: women out‐patients with tension headache
Baseline comparability: no (pre treatment headache index score) |
| Interventions |
Placebo: sessions with 'concentration therapy' and
‐positive therapist expectations
‐negative therapist expectations
Untreated: no sessions
Experimental: sessions with muscular relaxation therapy and
‐positive therapist expectations
‐negative therapist expectations
(Co‐intervention: NS) |
| Outcomes |
Pain (Headache index score)
Global therapist judgement of improvement
Global patient judgement of improvement |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Blinding?
Treatment provider |
Low risk |
'...the double blind design...' |
| Blinding?
Outcome assessor |
Unclear risk |
Not relevant as patient reported outcome |
| Incomplete outcome data addressed?
All outcomes |
High risk |
|
| 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 = 21 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Trial size < 49 |
