| Methods |
Design: five group parallel trial
Purpose: examine the effect of psychological treatments on compulsive nail biting |
| Participants |
Patients: out‐patients regarding nail biting a serious problem and a source of personal shame
Baseline comparability: yes |
| Interventions |
Placebo: factual information on nails, diseases of nails and of theories about pathological nail biting
Untreated: waiting list
Experimental: two types of psychological intervention separately, and one combined.
(Co‐intervention: NS) |
| Outcomes |
Length of nails (mm) and estimated frequency of nail biting (per day)
Estimated control over nail biting
Cosmetic appearance rate |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Unclear risk |
NS |
| Allocation concealment? |
Unclear risk |
NS |
| Blinding?
Treatment provider |
High risk |
Not described as double‐blind (placebo/psychological intervention) |
| Blinding?
Outcome assessor |
Low risk |
'Post‐test and follow‐up sessions were conducted by an experimenter who had no knowledge of the groups to which subjects had been assigned during treatment' |
| 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? |
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? |
High risk |
N = 20 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Trial size < 49 |
