title: The relationship between asthma and depression in primary care patients: a historical cohort and nested case control study.
abstract: OBJECTIVE
  Asthma and depression are common health problems in primary care. Evidence of a relationship between asthma and depression is conflicting.
  
  
  OBJECTIVE
  to determine 1. The incidence rate and incidence rate ratio of depression in primary care patients with asthma compared to those without asthma, and 2. The standardized mortality ratio of depressed compared to non-depressed patients with asthma.
  
  
  METHODS
  A historical cohort and nested case control study using data derived from the United Kingdom General Practice Research Database.
  
  
  METHODS
  11,275 incident cases of asthma recorded between 1/1/95 and 31/12/96 age, sex and practice matched with non-cases from the database (ratio 1:1) and followed up through the database for 10 years. 1,660 cases were matched by date of asthma diagnosis with 1,660 controls.
  
  
  METHODS
  number of cases diagnosed with depression, the number of deaths over the study period.
  
  
  RESULTS
  The rate of depression in patients with asthma was 22.4/1,000 person years and without asthma 13.8 /1,000 person years. The incident rate ratio (adjusted for age, sex, practice, diabetes, cardiovascular disease, cerebrovascular disease, smoking) was 1.59 (95% CI 1.48-1.71). The increased rate of depression was not associated with asthma severity or oral corticosteroid use. It was associated with the number of consultations (odds ratio per visit 1.09; 95% CI 1.07-1.11). The age and sex adjusted standardized mortality ratio for depressed patients with asthma was 1.87 (95% CI: 1.54-2.27).
  
  
  CONCLUSIONS
  Asthma is associated with depression. This was not related to asthma severity or oral corticosteroid use but was related to service use. This suggests that a diagnosis of depression is related to health seeking behavior in patients with asthma. There is an increased mortality rate in depressed patients with asthma. The cause of this needs further exploration. Consideration should be given to case-finding for depression in this population.
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, King's College London, London, United Kingdom. p.walters@iop.kcl.ac.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Walters
authors.forename: Peter
authors.initials: P
authors.lastname: Schofield
authors.forename: Louise
authors.initials: L
authors.lastname: Howard
authors.forename: Mark
authors.initials: M
authors.lastname: Ashworth
authors.forename: André
authors.initials: A
authors.lastname: Tylee
mesh_terms: D001249:Asthma / Q000150:complications*; D016022:Case-Control Studies; D015331:Cohort Studies; D003863:Depression / Q000150:complications*; D006801:Humans; D011320:Primary Health Care; D006113:United Kingdom