Effect of opioid analgesics on emergency department length of stay among low back pain patients in the United States

Objectives: The objective of this study was to compare emergency department (ED) length of stay (LOS) between patients treated with opioid analgesia versus non-opioid analgesia for low back pain (LBP) in the ED. Methods: We conducted a secondary analysis of National Hospital Ambulatory Medical Care Survey (NHAMCS) data (2014–2015). Adults (age ≥18 years) who presented to the ED with a reason for visit or primary diagnosis of LBP were included in the final study sample. Patient visits were categorized into two groups based on whether they received opioid analgesia (with or without non-opioid analgesia) or non-opioid analgesia only in the ED. The primary outcome measure was ED LOS, which was log-transformed (as ED LOS was not normally distributed) for analysis. A multivariable linear regression analysis was used to evaluate the association between opioid use and ED LOS. Results: The study sample consisted of a national estimate of approximately 8.6 million ED visits for LBP (during 2014–2015), of which 60.1% received opioids and 39.9% received non-opioids only. The geometric mean ED LOS for patient visits who received opioids was longer than patient visits who received non-opioids (142 versus 92 min, respectively; p < 0.001). After adjusting for confounders in the multivariable analysis, patient visits that received opioids had a significantly longer ED LOS (coefficient 0.25; 95% CI 0.11 to 0.38; p < 0.001). Conclusions: In a nationally representative sample of patient visits to ED due to LBP in the US, use of opioids in the ED was associated with an increased ED LOS.