title: Emergency department visits for ambulatory care sensitive conditions: insights into preventable hospitalizations.
abstract: OBJECTIVE
  To explore whether differences in disease prevalence, disease severity, or emergency department (ED) admission thresholds explain why black persons, Medicaid, and uninsured patients have higher hospitalization rates for ambulatory care sensitive (ACS) conditions.
  
  
  METHODS
  The National Hospital Ambulatory Care Survey was used to analyze the ED utilization, disease severity (assessed by triage category), hospitalization rates, and follow-up plans for adults with five chronic ACS conditions (asthma, chronic obstructive lung disease, congestive heart failure, diabetes mellitus, and hypertension). The National Health Interview Survey was used to estimate the prevalence of these conditions in similarly aged US adults.
  
  
  RESULTS
  Black persons, Medicaid, and uninsured patients make up a disproportionate share of ED visits for these chronic ACS conditions. Cumulative prevalence of these conditions was higher in black persons (33%) compared with white persons (27%) and Hispanic persons (22%), but did not differ among the payment groups. All race or payment groups were assigned to similar triage categories and similar percentages of their ED visits resulted in hospitalization. Black persons and Hispanic persons (odds ratios for both = 0.7), were less likely than white persons, whereas Medicaid and uninsured patients (odds ratios for both = 0.8), were less likely than private patients to have follow-up with the physician who referred them to the ED.
  
  
  CONCLUSIONS
  The disproportionate ED utilization for chronic ACS conditions by black persons and Medicaid patients does not appear to be explained by either differences in disease prevalence or disease severity. Follow-up arrangements for black persons, Medicaid, and uninsured patients suggest that they are less likely to have ongoing primary care. Barriers to primary care appear to contribute to the higher ED and hospital utilization rates seen in these groups.
authors.affiliation: Division of General Internal Medicine and Primary Care Research Center, San Francisco General Hospital, University of California San Francisco, 94110, USA.
authors.forename: Ady
authors.initials: A
authors.lastname: Oster
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Bindman
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000553:Ambulatory Care / Q000706:statistics & numerical data; D002908:Chronic Disease / Q000453:epidemiology / Q000628:therapy; D003695:Delivery of Health Care / Q000592:standards; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006297:Health Services Accessibility; D006306:Health Surveys; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D017057:Medically Uninsured / Q000706:statistics & numerical data; D006278:Medicare / Q000706:statistics & numerical data; D008875:Middle Aged; D015995:Prevalence; D011320:Primary Health Care / Q000706:statistics & numerical data; D012494:Sampling Studies; D012720:Severity of Illness Index; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology