Contribution of verbal suggestion to the therapeutic efficacy of an analgesic agent for acute primary headache.

Objective: The therapeutic response of a patient cannot purely be explained by the method of therapy or the efficacy of a drug. Clinician-patient interaction, psychosocial factors, patients' expectations, hopes, beliefs and fears are all related to the healing outcome. Malleability and suggestibility are also important in the placebo or nocebo effect. The purpose of this study was to evaluate whether adding brief verbal suggestions for pain relief could change the magnitude of an analgesic's efficacy.

Methods: This prospective study was performed in the emergency department of a university hospital. Patients who were ordered analgesia with diclofenac sodium for primary headache were divided into three groups. All groups were informed that they would be administered a pain killer by intramuscular injection. The second and third groups were given positive and reduced treatment expectations about the therapeutic efficacy, respectively. Patients were asked to rate their pain on a VAS at 0 and 45 minutes and if they needed any additional analgesic 45 minutes after the injection.

Results: A total of 153 patients were included in the study. The paired univariate analyses showed significant differences for all groups between 0- and 45-minute VAS scores. However, there was no difference between the three groups according to the differences in VAS scores between 45 and 0 minutes and according to the administration of an additional drug.

Conclusion: Simple verbal suggestions did not alter the efficacy of an analgesic agent for headache in an emergency setting. The contributions of suggestibility, desire and expectation in acute primary headache patients should be further investigated.