The placebo effect in acute headache management: Ketorolac, meperidine, and saline in the emergency department

In a prospective, double-blind, randomized study, ketorolac 60 mg, meperidine 50 mg plus promethazine 25 mg, and normal saline given by intramuscular injection were compared as treatment for acute headache crises. Thirty patients (6 men and 24 women) presenting to an urban emergency department with any type of benign headache were randomized into three groups and filled out the McGill Short-Form Pain Questionnaire with a Pain Rating Index and a Visual Analogue Pain scale. They received one of the study medications and repeated the testing after 1 hour. The objective was to test the efficacy of ketorolac in this population. Separate analyses of the McGill Short-Form (Total, Sensory, Affective, and Pain Rating Index scales) and the Visual Analogue Pain scale responses showed that the three treatments produced a significant reduction in pain (P<.0001), but that pain reduction did not differ among the treatments. This profound reduction observed after administration of a placebo prevented accurate evaluation of the effects of ketorolac. The placebo response must be considered in the design of future trials using intramuscular medications in the acute intervention of headache crises. In addition, the use of a standard analgesic is necessary to demonstrate both assay sensitivity and magnitude of response to placebo.