title: Hospitalization rates and utilization among patients with giant cell arteritis: A population-based study from 1987 to 2012.
abstract: BACKGROUND
  Patients with giant cell arteritis (GCA) may experience serious vascular and visual complications. It is unknown, however, to what extent the difficulties of the disease may lead to hospitalization. The goal of this study is to discern whether patients with GCA are at greater risk for all-cause hospitalizations when compared to the general population.
  
  
  METHODS
  This retrospective, population-based cohort study utilized patients with large vessel or visual involvement who were diagnosed with GCA (as defined by the 1990 ACR criteria) between 1/1/1950 and 12/31/2009, and a reference cohort of patients without GCA matched on age, sex, and calendar year. Each patients' medical record was examined for hospitalizations from 1987 through 2012. For this analysis, follow-up began with the latter of index date or 1/1/1987 and ended at the earlier of death, emigration from Olmsted County, or 12/31/2012. Discharge diagnoses were grouped together using the Clinical Classifications Software (CCS) for ICD-9-CM from Healthcare Cost and Utilization Project (HCUP). Data were analyzed using person-year methods and rate ratios comparing GCA to non-GCA.
  
  
  RESULTS
  The GCA cohort consists of 199 patients with a mean age of 76.2 (79.9% female) and follow-up of 8.2 years. The non-GCA cohort is comprised of 194 patients with a mean age of 75.7 (78.9% female) and follow-up of 8.6 years. The patients with GCA had 816 hospitalizations and the non-GCA patients had 737 hospitalizations. GCA patients proved to be at a marginally greater risk for all causes of hospitalization [rate ratio (RR) = 1.13; 95% confidence interval (CI): 1.02-1.25]; however, the rate of hospitalization for patients with and without GCA decreased significantly from 1987 to 2012. Two specific discharge categories are of interest. First, transient cerebral ischemia is a greater risk of hospitalization for patients with GCA who had 16 hospitalizations compared to patients without GCA who only had 5 hospitalizations (RR = 3.06; 95% CI: 1.27-9.47). Second, patients with GCA (21 hospitalizations) are at greater risk of hospitalization for syncope than patients without GCA (5 hospitalizations) (RR = 3.98; 95% CI: 1.72-12.14).
  
  
  CONCLUSIONS
  In this first ever analysis of all-cause hospitalizations in a population-based cohort, patients with GCA appear to be at a marginally greater risk for hospitalization than patients without GCA, although the rate of hospitalization for GCA patients decreased from 1987 to 2012. Patients with GCA are at increased risk of hospitalization for both transient cerebral ischemia and syncope.
authors.affiliation: Department of Internal Medicine, Mayo Clinic, 200 1st St SW, Rochester 55905, MN.
authors.forename: Clement John
authors.initials: CJ
authors.lastname: Michet
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN.
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Achenbach
authors.affiliation: Department of Internal Medicine, Mayo Clinic, 200 1st St SW, Rochester 55905, MN; Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN.
authors.forename: Cynthia S
authors.initials: CS
authors.lastname: Crowson
authors.affiliation: Department of Internal Medicine, Mayo Clinic, 200 1st St SW, Rochester 55905, MN; Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, MN. Electronic address: Matteson.Eric@mayo.edu.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Matteson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D013700:Giant Cell Arteritis / Q000628:therapy*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Giant cell arteritis; Health utilization; Hospitalization
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