| Methods |
Design: two group, four period cross‐over trial with a third untreated group assessed after the first period
Purpose: examine the relationship between sensory suggestibility and treatment effect |
| Participants |
Patients: out‐patients suffering from chronic intermittent headaches
Baseline comparability: pretreatment headache scores |
| Interventions |
Placebo: tablet without metamizole
Untreated: no tablet
Experimental: tablet with metamizole
(Co‐intervention: NS) |
| Outcomes |
Pain (headache scores, 4‐item 6‐point scale)
Sensitivity values (d') |
| Notes |
The first period was considered a parallel trial. Results from later periods were disregarded. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Unclear risk |
NS |
| Allocation concealment? |
Unclear risk |
NS |
| Blinding?
Treatment provider |
Low risk |
|
| Blinding?
Outcome assessor |
Unclear risk |
NS |
| 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 = 30 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Trial size < 49 |
