title: Classifying Chronic Lower Respiratory Disease Events in Epidemiologic Cohort Studies.
abstract: One in 12 adults has chronic obstructive pulmonary disease or asthma. Acute exacerbations of these chronic lower respiratory diseases (CLRDs) are a major cause of morbidity and mortality. Valid approaches to classifying cases and exacerbations in the general population are needed to facilitate prevention research.
  
  
  
  To assess the feasibility, reproducibility, and performance of a protocol to identify CLRD cases and exacerbations triggering emergency department (ED) visits or hospitalizations in cohorts of patients derived from general populations of adults.
  
  
  
  A protocol was developed to classify CLRD cases and severe exacerbations on the basis of review of medical records. ED and inpatient medical records were ascertained prospectively in the Hispanic Community Health Study/Study of Latinos, and inpatient records were retrospectively identified by administrative codes in the Multi-Ethnic Study of Atherosclerosis. "Probable" exacerbations were defined as a physician's diagnosis of CLRD with acute respiratory symptoms. "Highly probable" exacerbations additionally required systemic corticosteroid therapy, and "definite" exacerbations required airflow limitation or evidence of CLRD on imaging studies. Adjudicated results were compared with CLRD cases identified by spirometry and self-report, and with an administrative definition of exacerbations.
  
  
  
  Protocol-based classification was completed independently by two physicians for 216 medical records (56 ED visits and 61 hospitalizations in the Hispanic Community Health Study/Study of Latinos; 99 hospitalizations in the Multi-Ethnic Study of Atherosclerosis). Reviewer disagreement occurred in 2-5% of cases and 4-8% of exacerbations. Eighty-nine percent of records were confirmed as at least probable CLRD cases. Fifty-six percent of confirmed CLRD cases had airflow limitation on the basis of baseline study spirometry. Of records that described CLRD as the primary discharge diagnosis code, an acute exacerbation was confirmed as at least probable for 96% and as highly probable or definite for 77%. Only 50% of records with CLRD as a secondary code were confirmed, although such records accounted for over half of all confirmed exacerbations.
  
  
  
  CLRD cases and severe exacerbations without preceding documentation of airflow limitation are identified frequently in population-based cohorts of persons. A primary discharge diagnosis of CLRD is specific but insensitive for defining exacerbations. Protocol-based classification of medical records may be appropriate to supplement and to validate identification of CLRD cases and exacerbations in general population studies. Clinical trials registered with www.clinicaltrials.gov (NCT00005487 and NCT02060344).
authors.affiliation: 1 Department of Medicine and.|2 Department of Epidemiology, Columbia University, New York, New York.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Oelsner
authors.affiliation: 3 Department of Epidemiology and.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Loehr
authors.affiliation: 4 Department of Medicine, University of North Carolina, Chapel Hill, North Carolina.
authors.forename: Ashley G
authors.initials: AG
authors.lastname: Henderson
authors.affiliation: 1 Department of Medicine and.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Donohue
authors.affiliation: 5 Department of Medicine, University of Arizona, Tucson, Arizona.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Enright
authors.affiliation: 6 Department of Medicine, Northwestern University, Evanston, Illinois.
authors.forename: Ravi
authors.initials: R
authors.lastname: Kalhan
authors.affiliation: 1 Department of Medicine and.
authors.forename: Christian M
authors.initials: CM
authors.lastname: Lo Cascio
authors.affiliation: 7 Department of Medicine, University of California, San Diego, La Jolla, California.
authors.forename: Andrew
authors.initials: A
authors.lastname: Ries
authors.affiliation: 8 Icahn School of Medicine at Mount Sinai Hospital, New York, New York; and.
authors.forename: Neomi
authors.initials: N
authors.lastname: Shah
authors.affiliation: 1 Department of Medicine and.|9 Department of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Smith
authors.affiliation: 3 Department of Epidemiology and.
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Rosamond
authors.affiliation: 1 Department of Medicine and.|2 Department of Epidemiology, Columbia University, New York, New York.
authors.forename: R Graham
authors.initials: RG
authors.lastname: Barr
mesh_terms: D000328:Adult; D000368:Aged; D018450:Disease Progression; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012140:Respiratory Tract Diseases / Q000145:classification* / Q000453:epidemiology*; D057566:Self Report; D013147:Spirometry; D014481:United States
keywords: administrative data; asthma; chronic obstructive pulmonary disease; disease progression; incidence