Emergency room resource utilization by patients with low-back pain

OBJECTIVE The objective of this study was to determine factors associated with admission to the hospital through the emergency room (ER) for patients with a primary diagnosis of low-back pain (LBP). The authors further evaluated the impact of ER admission and patient characteristics on mortality, discharge disposition, and hospital length of stay. METHODS The authors conducted a retrospective analysis of patients with LBP discharged from hospitals according to the Nationwide Inpatient Sample (NIS) between 1998 and 2007. Univariate comparisons of patient characteristics according to the type of admission (ER versus non-ER) were conducted. Multivariate analysis evaluated factors associated with an ER admission, risk of mortality, and nonroutine discharge. RESULTS According to the NIS, approximately 183,151 patients with a primary diagnosis of LBP were discharged from US hospitals between 1998 and 2007. During this period, an average of 65% of these patients were admitted through the ER, with a significant increase from 1998 (54%) to 2005 (71%). Multivariate analysis revealed that uninsured patients (OR 2.1, 95% CI 1.7-2.6, p < 0.0001) and African American patients (OR 1.5, 95% CI 1.2-1.7, p < 0.0001) were significantly more likely to be admitted through the ER than private insurance patients or Caucasian patients, respectively. Additionally, a moderate but statistically significant increase in the likelihood of ER admission was noted for patients with more preexisting comorbidities (OR 1.1, 95% CI 1.0-1.2, p < 0.001). An 11% incremental increase in the odds of admission through the ER was observed with each year increment (OR 1.1, 95% CI 1.0-1.2, p < 0.001). Highest income patients ($45,000+) were more likely to be admitted through the ER (OR 1.3, 95% CI 1.1-1.6, p = 0.007) than the lowest income cohort. While ER admission did not impact the risk of mortality (OR 0.95, 95% CI 0.60-1.51, p = 0.84), it increased the odds of a nonroutine discharge (OR 1.39, 95% CI 1.26-1.53, p < 0.0001). CONCLUSIONS A significant majority of patients discharged from hospitals in the US from 1998 to 2007 with a primary diagnosis of LBP were admitted through the ER, with more patients being admitted via this route each year. These patients were less likely to be discharged directly home compared with patients with LBP who were not admitted through the ER. Uninsured and African American patients with LBP were more likely to be admitted through the ER than their counterparts, as were patients with more preexisting health problems. Interestingly, patients with LBP at the highest income levels were more likely to be admitted through hospital ERs. The findings suggest that socioeconomic factors may play a role in the utilization of ER resources by patients with LBP, which in turn appears to impact at least the short-term outcome of these patients.