title: Data enhancement for co-morbidity measurement among patients referred for sleep diagnostic testing: an observational study.
abstract: BACKGROUND
  Observational outcome studies of patients with obstructive sleep apnea (OSA) require adjustment for co-morbidity to produce valid results. The aim of this study was to evaluate whether the combination of administrative data and self-reported data provided a more complete estimate of co-morbidity among patients referred for sleep diagnostic testing.
  
  
  METHODS
  A retrospective observational study of 2149 patients referred for sleep diagnostic testing in Calgary, Canada. Self-reported co-morbidity was obtained with a questionnaire; administrative data and validated algorithms (when available) were also used to define the presence of these co-morbid conditions within a two-year period prior to sleep testing.
  
  
  RESULTS
  Patient self-report of co-morbid conditions had varying levels of agreement with those derived from administrative data, ranging from substantial agreement for diabetes (kappa = 0.79) to poor agreement for cardiac arrhythmia (kappa = 0.14). The enhanced measure of co-morbidity using either self-report or administrative data had face validity, and provided clinically meaningful trends in the prevalence of co-morbidity among this population.
  
  
  CONCLUSIONS
  An enhanced measure of co-morbidity using self-report and administrative data can provide a more complete measure of the co-morbidity among patients with OSA when agreement between the two sources is poor. This methodology will aid in the adjustment of these coexisting conditions in observational studies in this area.
authors: Department of Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Canada. peronksl@ucalgary.ca
authors: Paul E
authors: PE
authors: Ronksley
authors: Willis H
authors: WH
authors: Tsai
authors: Hude
authors: H
authors: Quan
authors: Peter
authors: P
authors: Faris
authors: Brenda R
authors: BR
authors: Hemmelgarn
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015897:Comorbidity; D048909:Diabetes Complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology