Background: Suggestive interventions such as hypnosis and therapeutic suggestions are frequently used to alleviate surgical side effects; however, the effectiveness of therapeutic suggestion intervention has not yet been systematically evaluated. In the present study, we tested the hypotheses that (1) suggestive interventions are useful for reducing postoperative side effects; (2) therapeutic suggestions are comparable in effectiveness to hypnosis; (3) live presentation is more effective than recordings; and (4) suggestive interventions would be equally effective used in minor and major surgeries.
Methods: We performed random effect meta-analysis with meta-regression and sensitivity analysis by moderating factors on a pool of 26 studies meeting the inclusion criteria (N = 1890). Outcome variables were postoperative anxiety, pain intensity, pain medication requirement, and nausea.
Results: Suggestive interventions reduced postoperative anxiety (g = 0.40; 99% confidence interval [CI] = 0.13-0.66; P < 0.001) and pain intensity (g = 0.25; 99% CI = 0.00-0.50; P = 0.010), but did not significantly affect postoperative analgesic drug consumption (g = 0.16; 99% CI = -0.16 to 0.47; P = 0.202) and nausea (g = 0.38; 99% CI = -0.06 to 0.81; P = 0.026). No significant differences were found for intervention type, presentation method, and severity of surgery; however, sensitivity analysis only supported the effectiveness of hypnosis (g = 0.62; 99% CI = 0.31-0.92; P < 0.001) and live presentation (g = 0.55; 99% CI = 0.23-0.88; P < 0.001) for decreasing postoperative anxiety, and that of live presentation for alleviating postoperative pain (g = 0.44; 99% CI = 0.07-0.82; P = 0.002). Sensitivity analyses also suggested that suggestive interventions are only effective for decreasing pain intensity during minor surgical procedures (g = 0.39; 99% CI = 0.00-0.78; P = 0.009).
Conclusions: Suggestive techniques might be useful tools to alleviate postoperative anxiety and pain; however, strength of the evidence is weak because of possible bias in the reviewed articles. The lack of access to within-subjects data and the overlap between moderator conditions also limit the scope of the analysis. More methodologically correct studies are required with sensitivity to moderating factors and to within-subjects changes. For clinical purposes, we advise the use of hypnosis with live presentation to reduce postoperative anxiety and pain, until convincing evidence is uncovered for the effectiveness of therapeutic suggestions and recorded presentation. Pain management with adjunct suggestive interventions is mostly encouraged in minor rather than major surgeries.