Does Analgesia Really Need to Be Painful?
Abstract & Commentary
Source: Schwartz NA, et al. Patients’ perception of route of nonsteroidal anti-inflammatory drug administration and its efficacy on analgesia. Acad Emerg Med 2000;7:857-861.
The authors of this study sought to determine whether emergency department (ED) patients perceive intramuscular (IM) injections of nonsteroidal anti-inflammatory drugs (NSAIDs) to be more effective than oral NSAIDs for pain control. ED patients were enrolled in this convenience study if they had a musculoskeletal injury within the past 48 hours. Patients with penetrating trauma, suspected visceral injury, and back pain were excluded. In an unusual study design, patients were provided with a deliberately vague consent form that implied that they would receive either an IM analgesic or an oral analgesic, as well as a drink to maintain hydration. In reality, all patients were given a liquid containing 800 mg ibuprofen, after which they received either a placebo IM injection or a placebo pill in a blinded, randomized fashion. Patients were asked to rate their pain before NSAID administration and at 30-minute intervals using a 10 cm visual analog scale (VAS).
Sixty-four patients completed the study. The baseline VAS score was comparable between the IM and oral groups. After two hours, the mean VAS scores declined from about 6 cm to about 3 cm in each group and did not differ statistically. The pain scores also did not differ between the groups at any time interval. The authors conclude that IM administration of NSAIDs offers no selective placebo effect, and that routine use of parenteral analgesics is not warranted.
Comment by David J. Karras, MD, FAAEM, FACEP
There is considerable folklore surrounding IM analgesic use in the ED, and many practitioners believe patients find parenteral analgesics more effective than equipotent oral medication. This often is attributed to a placebo effect conferred by the painful injection, faster onset of action with IM administration, or a presupposition that ED patients "don’t come here to get a pill for their pain" and will be dissatisfied with anything less than a shot. While placebo effects should never be underestimated, such beliefs regarding advantages of analgesic injections have never stood up to investigation. Several prior studies have demonstrated that patients find no difference in pain relief whether given IM or oral NSAIDs for acute musculoskeletal pain.1,2 Nonetheless, these studies do not address whether patients are biased to perceive a "pain shot" as inherently more effective than a "pain pill." In the present study, the authors negated any physiologic differences in analgesic effect between the two routes of administration by giving all patients the same oral analgesic. Then they compared pain scores between those patients thinking they had received a shot to those thinking they had received a pill.
I have some nagging ethical concerns with the study in that the authors obtained consent after providing deliberately vague (and presumably misleading) information. The bottom line, however, is that all subjects received an effective ibuprofen dose. With studies like these, it’s getting harder to find indications for ketorolac other than a vomiting or NPO patient. The associated cost savings, reduction of needle-stick injury risk, elimination of painful drug administration, and equivalent efficacy of oral NSAIDs are strong arguments against routine use of NSAID injections in the ED.
References
1. Turturro MA, et al. Intramuscular ketorolac versus oral ibuprofen in acute musculoskeletal pain. Ann Emerg Med 1995;26:117-120.
2. Neighbor ML, Puntillo KA. Intramuscular ketorolac vs oral ibuprofen in emergency department patients with acute pain. Acad Emerg Med 1998;5:118-122.
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