| Methods |
Design: five group parallel trial
Purpose: examine the mechanism of placebo effects in ultrasound treatment |
| Participants |
Patients: postoperative in‐patients (after removal of impacted third molars)
Baseline comparability: NS |
| Interventions |
Placebo a: ultrasound without massage and machine off
Placebo b: ultrasound with massage and machine off
Untreated: no ultrasound or massage
Experimental a: ultrasound without massage and machine on
Experimental b: ultrasound with massage and machine on
(Co‐intervention: analgesics on demand) |
| Outcomes |
Pain (VAS) and facial swelling (cubic cm)
C‐reactive protein
Trismus
Plasma cortisol
Anxiety |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Low risk |
'random number tables' |
| Allocation concealment? |
Unclear risk |
NS |
| Blinding?
Treatment provider |
Low risk |
'In a placebo‐controlled double‐blind clinical trial...' |
| Blinding?
Outcome assessor |
Low risk |
'All assessments and measurements were performed by an investigator (I.H.) who was unaware of the treatment group to which the patient has been allocated' |
| 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? |
Low risk |
No variance inequality (F‐test not statistically significant) and no skewness (1.64 standard deviations does not exceed the mean) |
| Trial size > 49? |
Low risk |
N = 50 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Allocation not clearly concealed |
