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).

METHODS : Secondary data analysis of the ED component of National Hospital Ambulatory Medical Care Survey (2014-2015), a nationally representative database of the United States (US) was conducted. Adults (age≥ 18 years) with a reason for visit or primary ICD-9-CM diagnosis of LBP were included. Patients were excluded if they had a reason for visit related to motor vehicle collisions, did not receive any analgesics, transferred to psychiatric hospital, nursing home, or other hospital, left against medical advice, admitted for inpatient treatment, or died. Patient visits were categorized into two groups: receipt of opioid analgesia (with or without non-opioid analgesia) or non-opioid analgesia only in the ED. ED LOS was log-transformed to improve normality. A multivariable linear regression analysis was used to evaluate the association between opioid use and log-transformed ED LOS.

RESULTS : The final study sample consisted of approximately 8.6 million ED visits (US national-level) for LBP during 2014-2015. Of these, 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 minutes, respectively; p<0.001). Using multivariable regression analysis opioid analgesic use was associated with increased log-transformed ED LOS ( =0.25, p<0.001, 95% CI: 0.11 to 0.38).

CONCLUSIONS : In a nationally representative sample of ED patient visits due to LBP in the US, use of opioids was associated with an increased ED LOS.