title: Anemia in chronic obstructive pulmonary disease: epidemiology and economic implications.
abstract: BACKGROUND
  Anemia in chronic illness is associated with increased healthcare resource utilization (HRU) and costs. In COPD, it occurs frequently and influences both clinical and economic outcomes. Because no data studies have been performed either in a single center or a subpopulation of COPD patients, anemia's influence on the outcomes is not fully understood.
  
  
  METHODS
  We conducted a retrospective cohort study in a large healthcare database to quantify prevalence, HRU and costs of anemia in COPD. From 1997 to 2005, patients > or = 45 years of age with an ICD-9 diagnosis code for COPD and > 3.5 years of follow-up were included. Anemia was defined by the WHO criteria. Other disease states for which anemia is a known complication were excluded. We calculated the prevalence of anemia and compared annual HRU and costs between COPD patients with and without anemia. Multiple regression analysis adjusted for the effects of age, gender, race, length of enrollment, diagnosing physician specialty, co-morbidity burden, anemia and COPD severity.
  
  
  RESULTS
  Of the 2404 patients with COPD, 33% (n = 788) had a diagnosis of anemia. Anemic patients were older, more likely to be male and non-Caucasian, and had a greater co-morbidity burden than non-anemic individuals. Annual costs for COPD patients with anemia were more than twice those for patients without anemia ($17,240 vs. 6492, p < 0.001, unadjusted). HRU was also significantly greater among anemic than non-anemic COPD patients (p < 0.0001). In a multiple regression analysis, anemia accounted for $7929 per patient (95% CI: $5572-10,599) of the total costs of care.
  
  
  CONCLUSIONS
  This is a retrospective cohort study and thus subject to multiple forms of bias. Although spirometric evidence of COPD was available only for a subgroup of patients, our case identification methods have been previously validated and found to be accurate in recognizing COPD.
  
  
  CONCLUSIONS
  Anemia is a common co-morbidity in COPD. It is significantly associated with an increase in HRU and costs of care for COPD, independent of demographic and clinical patient characteristics.
authors.affiliation: Washington Hospital Center, Washington, DC 20010, USA. afshorr@dnamail.com
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Shorr
authors.forename: John
authors.initials: J
authors.lastname: Doyle
authors.forename: Lee
authors.initials: L
authors.lastname: Stern
authors.forename: Margarita
authors.initials: M
authors.lastname: Dolgitser
authors.forename: Marya D
authors.initials: MD
authors.lastname: Zilberberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000740:Anemia / Q000191:economics* / Q000453:epidemiology* / Q000209:etiology; D019992:Databases as Topic; D005260:Female; D017048:Health Care Costs; D006295:Health Resources / Q000706:statistics & numerical data*; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000191:economics; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology