Comparative Effectiveness of Patient-Controlled Analgesia for Treating Acute Pain in the Emergency Department

Abstract

We assess the effectiveness of patient-controlled analgesia in the emergency department (ED). We hypothesized that decline in pain intensity from 30 to 120 minutes after initial intravenous opioid administration is greater in patients receiving morphine by patient-controlled analgesia compared with usual care and would differ by a clinically significant amount. This was a pragmatic randomized controlled trial of patient-controlled analgesia and usual care (opioid and dose at physician's discretion) in 4 EDs. Entry criteria included age 18 to 65 years and acute pain requiring intravenous opioids. The primary outcome was decline in numeric rating scale pain score 30 to 120 minutes postbaseline. Secondary outcomes included satisfaction, time to analgesia, adverse events, and patient-controlled analgesia pump-related problems. We used a mixed-effects linear model to compare rate of decline in pain (slope) between groups. A clinically significant difference between groups was defined as a difference in slopes equivalent to 1.3 numeric rating scale units. Six hundred thirty-six patients were enrolled. The rate of decline in pain from 30 to 120 minutes was greater for patients receiving patient-controlled analgesia than usual care (difference=1.0 numeric rating scale unit; 95% confidence interval [CI] 0.6 to 1.5; P<.001) but did not reach the threshold for clinical significance. More patients receiving patient-controlled analgesia were satisfied with pain management (difference=9.3%; 95% CI 3.3% to 15.1%). Median time to initial analgesia was 15 minutes longer for patient-controlled analgesia than usual care (95% CI 11.4 to 18.6 minutes). There were 7 adverse events in the patient-controlled analgesia group and 1 in the usual care group (difference=2.0%; 95% CI 0.04% to 3.9%), and 11 pump-programming errors. The findings of this study do not favor patient-controlled analgesia over usual ED care for acute pain management.