| Methods |
Design: four group parallel trial
Purpose: examine the effect of behavioural therapy and placebo on snake and spider phobia |
| Participants |
Patients: out‐patients suffering from phobia against snakes and spiders
Baseline comparability: yes |
| Interventions |
Placebo:
‐with feedback: patients told that pictures with phobic stimulus would be flickered too rapidly for the conscious mind to register and phobic responses would be detected by a 'polygraph' that would deliver a mild but uncomfortable electrical shock. In fact only light was shown and no machine detected any phobias. The rate of shocks associated with lights was programmed to be reduced from 90% in the first session to 10% in the last session. The patients were shown outprints and explained that treatment was 'going well'.
‐ without feedback: similar procedure, but no outprints were shown and patients told that the machine reduced the number of shocks independently of their response. Patients were also 'assured throughout treatment that things were going well'
Untreated: no behavioural or placebo procedure (waiting‐list)
Experimental: systematic desensitization procedure
(Co‐intervention: NS) |
| Outcomes |
Percentage of fear remaining (index) and pulse rate at confrontation with snake or spider
Behavioural approach test
Behavioural inhibition test
Reaction to picture test
Global behavioural improvement
Therapy expectancy
Warmth and competence of therapist |
| 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/behavioural therapy) |
| Blinding?
Outcome assessor |
Low risk |
'... experimenter who was blind to the conditions that the subjects had been assigned' |
| 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? |
Unclear risk |
Not relevant (not naturally positive continuous outcomes e.g. change) |
| Trial size > 49? |
High risk |
N = 18 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Trial size < 49 |
