title: The prevalence of multimorbidity in primary care and its effect on health care utilization and cost.
abstract: BACKGROUND
  Multimorbidity is common among the heterogeneous primary care population, but little data exist on its association with health care utilization or cost.
  
  
  OBJECTIVE
  The aim of this observational study was to examine the prevalence and associated health care utilization and cost of patients with multimorbidity.
  
  
  METHODS
  All patients >50 years of age were eligible for the study which took place in three primary care practices in the West of Ireland. Chronic medical conditions and associated health care utilization in primary and secondary care were identified through patient record review.
  
  
  RESULTS
  In a sample of 3309 patients in the community, the prevalence of multimorbidity was 66.2% (95% CI: 64.5-67.8) in those >50 years of age. Health care utilization and cost was significantly increased among patients with multimorbidity (P < 0.001). After multivariate adjustment for age, gender and free medical care eligibility, the addition of each chronic condition led to an associated increase in primary care consultations (P = 0.001) (11.9 versus 3.7 for >4 conditions versus 0 conditions); hospital out-patient visits (P = 0.001) (3.6 versus 0.6 for >4 conditions versus 0 conditions); hospital admissions (P = 0.01) [adjusted odds ratio (OR) of 4.51 for >4 conditions versus 0 conditions] and total health care costs (P < 0.001) (€4,096.86 versus €760.20 for >4 conditions versus 0 conditions) over the previous 12 months.
  
  
  CONCLUSIONS
  Multimorbidity is very common in primary care and in a system with strong gatekeeping is associated with high health care utilization and cost across the health care system. Interventions to address quality and cost associated with multimorbidity must focus on primary as well as secondary care.
authors: Department of General Practice, National University of Ireland, Galway, Ireland. liam.glynn@nuigalway.ie
authors: Liam G
authors: LG
authors: Glynn
authors: Jose M
authors: JM
authors: Valderas
authors: Pamela
authors: P
authors: Healy
authors: Evelyn
authors: E
authors: Burke
authors: John
authors: J
authors: Newell
authors: Patrick
authors: P
authors: Gillespie
authors: Andrew W
authors: AW
authors: Murphy
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000191:economics / Q000706:statistics & numerical data; D002908:Chronic Disease / Q000191:economics / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006296:Health Services / Q000191:economics* / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009819:Office Visits / Q000191:economics / Q000706:statistics & numerical data; D015995:Prevalence; D011320:Primary Health Care / Q000706:statistics & numerical data*