title: Multimorbidity and quality of life in primary care: a systematic review.
abstract: BACKGROUND
  Many patients with several concurrent medical conditions (multimorbidity) are seen in the primary care setting. A thorough understanding of outcomes associated with multimorbidity would benefit primary care workers of all disciplines. The purpose of this systematic review was to clarify the relationship between the presence of multimorbidity and the quality of life (QOL) or health-related quality of life (HRQOL) of patients seen, or likely to be seen, in the primary care setting.
  
  
  METHODS
  Medline and Embase electronic databases were screened using the following search terms for the reference period 1990 to 2003: multimorbidity, comorbidity, chronic disease, and their spelling variations, along with quality of life and health-related quality of life. Only descriptive studies relevant to primary care were selected.
  
  
  RESULTS
  Of 753 articles screened, 108 were critically assessed for compliance with study inclusion and exclusion criteria. Thirty of these studies were ultimately selected for this review, including 7 in which the relationship between multimorbidity or comorbidity and QOL or HRQOL was the main outcome measure. Major limitations of these studies include the lack of a uniform definition for multimorbidity or comorbidity and the absence of assessment of disease severity. The use of self-reported diagnoses may also be a weakness. The frequent exclusion of psychiatric diagnoses and presence of potential confounding variables are other limitations. Nonetheless, we did find an inverse relationship between the number of medical conditions and QOL related to physical domains. For social and psychological dimensions of QOL, some studies reveal a similar inverse relationship in patients with 4 or more diagnoses.
  
  
  CONCLUSIONS
  Our findings confirm the existence of an inverse relationship between multimorbidity or comorbidy and QOL. However, additional studies are needed to clarify this relationship, including the various dimensions of QOL affected. Those studies must employ a clear definition of multimorbidity or comorbidity and valid ways to measure these concepts in a primary care setting. Pursuit of this research will help to better understand the impact of chronic diseases on patients.
authors.affiliation: Département de Médecine de famille, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, Québec, J1H 5N4 Canada. martinfortin@videotron.ca
authors.forename: Martin
authors.initials: M
authors.lastname: Fortin
authors.forename: Lise
authors.initials: L
authors.lastname: Lapointe
authors.forename: Catherine
authors.initials: C
authors.lastname: Hudon
authors.forename: Alain
authors.initials: A
authors.lastname: Vanasse
authors.forename: Antoine L
authors.initials: AL
authors.lastname: Ntetu
authors.forename: Danielle
authors.initials: D
authors.lastname: Maltais
mesh_terms: D002908:Chronic Disease / Q000453:epidemiology*; D015897:Comorbidity; D016206:Databases, Bibliographic; D006302:Health Services Research; D006305:Health Status Indicators; D006801:Humans; D017063:Outcome Assessment, Health Care; D011320:Primary Health Care / Q000706:statistics & numerical data*; D011788:Quality of Life