Fourteen RCTs (n=693) were included in the review. Overall the included trials were of poor methodological quality (one RCT scored 3 points, four RCTs scored 2 points, and nine RCTs scored 1 point).
Generalised or unspecified anxiety (three RCTs): One RCT reported that hypnosis was superior to both music relaxation (MD -9.40, 95% CI -16.36 to -2.44) and no treatment (MD -14.20, 95% CI -21.24 to -7.16) for reducing anxiety scores. However, one RCT reported that hypnosis was no more effective that meditation, and another RCT reported hypnosis was no more effective than no treatment.
Anxiety related to trauma (two RCTs): One RCT reported significant pre-treatment/post-treatment differences favouring hypnosis (p≤0.5) compared with waiting list for intrusion subscale of Impact of Event Scale-I, Symptom Check List-90 hostility subscale, and State Trait Anxiety Inventory state and trait scales. One RCT reported no significant differences between cognitive behavioural therapy plus hypnosis compared with cognitive behavioural therapy alone for pre-treatment/post-treatment change scores, in pre-treatment and six month follow-up change scores or at three year follow up.
Phobic anxiety (six RCTs): There were no significant differences between hypnosis groups compared with systematic desensitisation groups reported in one RCT for any outcome for the treatment of mixed phobic disorders. One RCT reported greater effectiveness in a group receiving hypnosis as part of a cognitive behavioural therapy program compared to a group receiving progressive relaxation as part of a cognitive behavioural therapy program (p<0.05). One RCT reported a significant difference in pre-treatment/post-treatment Performance Anxiety Inventory scores for a hypnosis group compared with a control condition for the treatment of performance-related social phobia (MD -7.60, 95% CI -13.25 to -1.95). One RCT reported no significant differences between hypnosis or psycho-physiologic therapy groups for treatment of dental phobia. Insufficient data precluded analysis of two further RCTs evaluating dental phobia.
Test/examination anxiety (three RCTs): One RCT reported a significantly greater reduction in anxiety scores for hypnosis compared with attention control group for test or examination anxiety among students (MD -23.00, 95% CI -43.67 to -2.33), but there were no statistically significant differences between hypnosis and systematic desensitisation groups. Another RCT reported that post-treatment scores were significantly lower, indicating lower levels of anxiety for the hypnosis group compared to contact/participation controls (p<0.001). While another RCT reported a significant reduction in test anxiety in school-age children for the hypnosis group compared with discussion control group in anxiety scores at post-test (MD -5.70, 95% CI -8.60 to 2.80) and at six months follow-up (MD -5.40, 95% CI -8.27 to -2.53).