title: Prevalence of depression and utilization of health care in single and multiple morbidity: a population-based cohort study.
abstract: BACKGROUND
  This study aimed to determine whether depression in patients with long-term conditions is associated with the number of morbidities or the type of co-morbidity. Method A cohort study of 299 912 participants aged 30-100 years. The prevalence of depression, rates of health-care utilization and costs were evaluated in relation to diagnoses of diabetes mellitus (DM), coronary heart disease (CHD), stroke and colorectal cancer.
  
  
  RESULTS
  The age-standardized prevalence of depression was 7% in men and 14% in women with no morbidity. The frequency of depression increased in single morbidities including DM (men 13%, women 22%), CHD (men 15%, women 24%), stroke (men 14%, women 26%) or colorectal cancer (men 10%, women 21%). Participants with concurrent diabetes, CHD and stroke had a very high prevalence of depression (men 23%, women 49%). The relative rate of depression for one morbidity was 1.63 [95% confidence interval (CI) 1.59-1.66], two morbidities 1.96 (95% CI 1.89-2.03) and three morbidities 2.35 (95% CI 2.03-2.59). Compared to those with no morbidity, depression was associated with higher rates of health-care utilization and increased costs at any level of morbidity. In women aged 55 to 64 years without morbidity, the mean annual health-care cost was £513 without depression and £1074 with depression; when three morbidities were present, the cost was £1495 without depression and £2878 with depression.
  
  
  CONCLUSIONS
  Depression prevalence and health-care costs are more strongly associated with the number of morbidities than the nature of the co-morbid diagnosis.
authors.affiliation: Department of Primary Care and Public Health Sciences, King's College London, UK. nawaraj.bhattarai@kcl.ac.uk
authors.forename: N
authors.initials: N
authors.lastname: Bhattarai
authors.forename: J
authors.initials: J
authors.lastname: Charlton
authors.forename: C
authors.initials: C
authors.lastname: Rudisill
authors.forename: M C
authors.initials: MC
authors.lastname: Gulliford
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000191:economics / Q000453:epidemiology*; D015897:Comorbidity; D003327:Coronary Disease / Q000191:economics / Q000453:epidemiology*; D003866:Depressive Disorder / Q000191:economics / Q000453:epidemiology*; D003920:Diabetes Mellitus / Q000191:economics / Q000453:epidemiology*; D005260:Female; D017048:Health Care Costs; D006296:Health Services / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D013222:State Medicine / Q000191:economics; D020521:Stroke / Q000191:economics / Q000453:epidemiology*; D006113:United Kingdom / Q000453:epidemiology