Explaining racial and ethnic disparities in waiting times at U.S. emergency departments

Background/Purpose: Emergency department (ED) crowding threatens access to and quality of care. Racial and ethnic disparities in U.S. ED waiting times have been observed previously. We sought to better understand disparities in waiting time by including two key variables, ED volume and boarding, not included in previous national analyses. Methods: We linked data from 63,744 visits to 457 EDs in the 2005-2006 National Hospital Ambulatory Medical Care Surveys with the SDI Hospital Marketing Profile Solution databases for 2006-2007. We compared waiting times among visits by non-Hispanic black and Hispanic patients with those of non-Hispanic white patients in regression models with hybrid fixed effects specification. We defined waiting time as time from arrival until the patient saw a physician. Waiting time data were log-transformed; consequently, geometric means and percent differences are reported. ED volume was measured annually. We defined a proxy for boarding as a visit at which: (1) the patient was admitted or transferred, and (2) time from treatment start to ED discharge was 6 hours or more. We also adjusted for triage status, hour of visit, patient age and sex, expected payment source, teaching hospital status, and inpatient hospital bed size. Results/Outcomes: In unadjusted models, the geometric mean waiting time for non-Hispanic white patients was 26 minutes. Non-Hispanic black and Hispanic patients waited 34% and 40% longer, respectively (p < .001 for both). In adjusted models, non-Hispanic black and Hispanic patients waited 18% and 21% longer (p < .001 for both). Within-ED differences were reduced to 3% (p = .07) for non-Hispanic black and 9% (p < .001) for Hispanic patients. Across EDs, waiting times were 5.7 % and 6.1% longer for every 10 percentage point increase in visits by black and Hispanic patients (p < .001 for both). Waiting time increased by 16% for every 10,000 visit increase in ED volume up to 50,000 visits (p < .001). Among EDs with volume greater than 50,000, waiting time did not vary. At EDs which boarded more than 5% of patients, waiting time was 23% longer (p = .009). Conclusions: Non-Hispanic black and Hispanic patients wait longer for ED treatment than non-Hispanic whites. These disparities are best explained by differences in where patients of different races/ethnicities receive care. Volume and boarding are both strongly associated with waiting times. Recent policy recommendations have emphasized the problem of boarding. A greater focus on ED volumes may also be warranted.