| Methods |
Design: two group parallel trial
Purpose: study the effect of placebo on cough |
| Participants |
Patients: out‐patients with cough and signs of upper respiratory infection
Baseline comparability: NS |
| Interventions |
Placebo: capsule with vitamin E
Untreated: no capsule
(Co‐intervention: no) |
| Outcomes |
Changes in cough frequency per 15 minutes
Cough suppression time |
| Notes |
Mean changes in cough frequency per 15 minutes calculated from individual patient data in Figure 1 |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Unclear risk |
NS |
| Allocation concealment? |
Unclear risk |
NS |
| Blinding?
Treatment provider |
Unclear risk |
NS |
| Blinding?
Outcome assessor |
Low risk |
'microphone connected to a pen recorder' |
| Incomplete outcome data addressed?
All outcomes |
Low risk |
Drop‐out < 15% |
| 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? |
Low risk |
N = 54 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Allocation not clearly concealed |
