title: Emergency department use and subsequent hospitalizations among members of a high-deductible health plan.
abstract: BACKGROUND
  Patients evaluated at emergency departments often present with nonemergency conditions that can be treated in other clinical settings. High-deductible health plans have been promoted as a means of reducing overutilization but could also be related to worse outcomes if patients defer necessary care.
  
  
  OBJECTIVE
  To determine the relationship between transition to a high-deductible health plan and emergency department use for low- and high-severity conditions and to examine changes in subsequent hospitalizations.
  
  
  METHODS
  Analysis of emergency department visits and subsequent hospitalizations among 8724 individuals for 1 year before and after their employers mandated a switch from a traditional health maintenance organization plan to a high-deductible health plan, compared with 59 557 contemporaneous controls who remained in the traditional plan. All persons were aged 1 to 64 years and insured by a Massachusetts health plan between March 1, 2001, and June 30, 2005.
  
  
  METHODS
  Rates of first and repeat emergency department visits classified as low, indeterminate, or high severity during the baseline and follow-up periods, as well as rates of inpatient admission after emergency department visits.
  
  
  RESULTS
  Between the baseline and follow-up periods, emergency department visits among members who switched to high-deductible coverage decreased from 197.5 to 178.1 per 1000 members, while visits among controls remained at approximately 220 per 1000 (-10.0% adjusted difference in difference; 95% confidence interval [CI], -16.6% to -2.8%; P = .007). The high-deductible plan was not associated with a change in the rate of first visits occurring during the study period (-4.1% adjusted difference in difference; 95% CI, -11.8% to 4.3%). Repeat visits in the high-deductible group decreased from 334.6 to 255.3 visits per 1000 members and increased from 321.1 to 334.4 per 1000 members in controls (-24.9% difference in difference; 95% CI, -37.5% to -9.7%; P = .002). Low-severity repeat emergency department visits decreased in the high-deductible group from 142.5 to 92.1 per 1000 members and increased in controls from 128.0 to 132.5 visits per 1000 members (-36.4% adjusted difference in difference; 95% CI, -51.1% to -17.2%; P<.001), whereas a small decrease in high-severity visits in the high-deductible group could not be excluded. The percentage of patients admitted from the emergency department in the high-deductible group decreased from 11.8 % to 10.9% and increased from 11.9% to 13.6% among controls (-24.7% adjusted difference in difference; 95% CI, -41.0% to -3.9%; P = .02).
  
  
  CONCLUSIONS
  Traditional health plan members who switched to high-deductible coverage visited the emergency department less frequently than controls, with reductions occurring primarily in repeat visits for conditions that were not classified as high severity, and had decreases in the rate of hospitalizations from the emergency department. Further research is needed to determine long-term health care utilization patterns under high-deductible coverage and to assess risks and benefits related to clinical outcomes.
authors.affiliation: Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, Mass 02215, USA. jwharam@partners.org
authors.forename: J Frank
authors.initials: JF
authors.lastname: Wharam
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Landon
authors.forename: Alison A
authors.initials: AA
authors.lastname: Galbraith
authors.forename: Ken P
authors.initials: KP
authors.lastname: Kleinman
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Soumerai
authors.forename: Dennis
authors.initials: D
authors.lastname: Ross-Degnan
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003669:Deductibles and Coinsurance; D004636:Emergency Service, Hospital / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D006279:Health Maintenance Organizations; D006297:Health Services Accessibility; D006760:Hospitalization / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007350:Insurance, Hospitalization; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D016012:Poisson Distribution; D014481:United States