title: Multimorbidity: prevalence, effect on quality of life and daily functioning, and variation of this effect when one condition is a rheumatic disease.
abstract: OBJECTIVE
  To examine the prevalence and effect of multimorbidity on health-related quality of life (HRQoL) and daily functioning in the general population, and to analyze the influence on HRQoL and daily functioning of multimorbidity including a rheumatic disease.
  
  
  METHODS
  A national health survey was conducted on 2192 randomly selected adults in Spain. Multimorbidity was defined as the co-occurrence of at least 2 chronic diseases, as defined by self-report. All subjects completed the 12-item short form (SF-12) health survey and the Health Assessment Questionnaire (HAQ). Estimates and 95% confidence intervals (CI) of the prevalence of multimorbidity were obtained. The effect on HAQ and SF-12 scores is presented as beta-coefficients obtained from multiple linear regressions.
  
  
  RESULTS
  The estimated prevalence of multimorbidity was 30% (95% CI 25 to 34), and the prevalence of multimorbidity including a rheumatic disease was 17% (95% CI 13 to 20). Multimorbidity was associated with impaired daily functioning [HAQ beta = 0.07 (95% CI 0.02 to 0.11)], and lower HRQoL [SF-12(physical component) beta = -4.2 (95% CI -5.2 to -3.22); SF-12(mental dimension) beta = -3.3 (95% CI -4.5 to -2.2)]. Subjects with multimorbidity including a rheumatic disease reported worse scores than those without a rheumatic disease: HAQ beta 0.13 (95% CI 0.07 to 0.18) versus -0.03 (95% CI -0.08 to 0.02), and SF-12(physical component) beta -6.5 (95% CI -5.2 to -3.2) versus 0.5 (95% CI -0.7 to 1.7).
  
  
  CONCLUSIONS
  Multimorbidity is frequent in the general population and can considerably impair daily functioning and HRQoL. Having a rheumatic disease worsens these outcomes.
authors.affiliation: Rheumatology Unit, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Estíbaliz
authors.initials: E
authors.lastname: Loza
authors.forename: Juan A
authors.initials: JA
authors.lastname: Jover
authors.forename: Luis
authors.initials: L
authors.lastname: Rodriguez
authors.forename: Loreto
authors.initials: L
authors.lastname: Carmona
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011788:Quality of Life; D012216:Rheumatic Diseases / Q000453:epidemiology*