title: Including information about co-morbidity in estimates of disease burden: results from the World Health Organization World Mental Health Surveys.
abstract: BACKGROUND
  The methodology commonly used to estimate disease burden, featuring ratings of severity of individual conditions, has been criticized for ignoring co-morbidity. A methodology that addresses this problem is proposed and illustrated here with data from the World Health Organization World Mental Health Surveys. Although the analysis is based on self-reports about one's own conditions in a community survey, the logic applies equally well to analysis of hypothetical vignettes describing co-morbid condition profiles.
  
  
  METHODS
  Face-to-face interviews in 13 countries (six developing, nine developed; n=31 067; response rate=69.6%) assessed 10 classes of chronic physical and nine of mental conditions. A visual analog scale (VAS) was used to assess overall perceived health. Multiple regression analysis with interactions for co-morbidity was used to estimate associations of conditions with VAS. Simulation was used to estimate condition-specific effects.
  
  
  RESULTS
  The best-fitting model included condition main effects and interactions of types by numbers of conditions. Neurological conditions, insomnia and major depression were rated most severe. Adjustment for co-morbidity reduced condition-specific estimates with substantial between-condition variation (0.24-0.70 ratios of condition-specific estimates with and without adjustment for co-morbidity). The societal-level burden rankings were quite different from the individual-level rankings, with the highest societal-level rankings associated with conditions having high prevalence rather than high individual-level severity.
  
  
  CONCLUSIONS
  Plausible estimates of disorder-specific effects on VAS can be obtained using methods that adjust for co-morbidity. These adjustments substantially influence condition-specific ratings.
authors.affiliation: Health Services Research Unit, Institut Municipal d'Investigació Mèdica (IMIM-Hospital del Mar), Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Alonso
authors.forename: G
authors.initials: G
authors.lastname: Vilagut
authors.forename: S
authors.initials: S
authors.lastname: Chatterji
authors.forename: S
authors.initials: S
authors.lastname: Heeringa
authors.forename: M
authors.initials: M
authors.lastname: Schoenbaum
authors.forename: T
authors.initials: T
authors.lastname: Bedirhan Üstün
authors.forename: S
authors.initials: S
authors.lastname: Rojas-Farreras
authors.forename: M
authors.initials: M
authors.lastname: Angermeyer
authors.forename: E
authors.initials: E
authors.lastname: Bromet
authors.forename: R
authors.initials: R
authors.lastname: Bruffaerts
authors.forename: G
authors.initials: G
authors.lastname: de Girolamo
authors.forename: O
authors.initials: O
authors.lastname: Gureje
authors.forename: J M
authors.initials: JM
authors.lastname: Haro
authors.forename: A N
authors.initials: AN
authors.lastname: Karam
authors.forename: V
authors.initials: V
authors.lastname: Kovess
authors.forename: D
authors.initials: D
authors.lastname: Levinson
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: M E
authors.initials: ME
authors.lastname: Medina-Mora
authors.forename: J
authors.initials: J
authors.lastname: Ormel
authors.forename: J
authors.initials: J
authors.lastname: Posada-Villa
authors.forename: H
authors.initials: H
authors.lastname: Uda
authors.forename: R C
authors.initials: RC
authors.lastname: Kessler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002908:Chronic Disease / Q000453:epidemiology*; D015897:Comorbidity; D017281:Cost of Illness; D003431:Cross-Cultural Comparison; D003865:Major Depressive Disorder / Q000453:epidemiology; D005260:Female; D015276:Health Care Rationing / Q000706:statistics & numerical data; D006291:Health Policy; D006305:Health Status Indicators; D006306:Health Surveys / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology*; D008875:Middle Aged; D009422:Nervous System Diseases / Q000453:epidemiology; D010147:Pain Measurement; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology; D019472:Universal Health Insurance / Q000706:statistics & numerical data; D014944:World Health Organization; D055815:Young Adult