Objective: There is a commonly held belief among health care providers that patients respond better to parenteral nonsteroidal anti-inflammatory drugs (NSAIDs) than to oral forms by virtue of the patients' belief that getting an injection means they are receiving "stronger" medicine. To the authors' knowledge, this effect has never been adequately documented in the literature. The objective of this study was to compare the effects of a placebo analgesic injection vs placebo oral analgesia on patients with acute musculoskeletal pain.
Methods: A convenience sample of emergency department (ED) patients with acute musculoskeletal pain secondary to trauma were enrolled. Patients received 225 mL of orange-flavored drink containing 800 mg of ibuprofen. Patients then received either a physiologically inactive starch tablet resembling ibuprofen 800 mg in taste and appearance or a physiologically inactive saline intramuscular (IM) injection resembling ketorolac 60 mg. Both patients and research nurses were blinded to the addition of ibuprofen to the drink and the inactive nature of subsequent medication. Pain was evaluated at time 0 and at 30, 60, 90, and 120 minutes on a 10-mm visual analog scale (VAS).
Results: Sixty-four patients completed the study protocol. The VAS scores between groups did not differ significantly at baseline or at each subsequent interval (p = 0.86).
Conclusions: These results contradict the belief that parenteral medications confer a selective placebo effect stemming from patients' beliefs regarding route of administration and efficacy. Therefore, the routine use of IM administration of NSAIDs for suspected enhanced analgesia appears unwarranted.