title: The prevalence of chronic diseases and multimorbidity in primary care practice: a PPRNet report.
abstract: BACKGROUND
  Multimorbidity (multiple chronic illnesses) greatly affects the delivery of health care and assessment of health care quality. There is a lack of basic epidemiologic data on multimorbidity in the United States. This article addresses the prevalence of 24 chronic illnesses and multimorbidity from primary care practices across the United States.
  
  
  METHODS
  This cross-sectional study was conducted in the PPRNet, a practice-based research network among 226 practices in 43 states that maintains a clinical database derived from a common electronic health record. Practices providing data as of October 1, 2011, and their active adult patients comprised the population used for analyses. The prevalence of each chronic illness and multimorbidity were calculated.
  
  
  RESULTS
  Included in these analyses were 148 practices with 667,379 active patients. Median prevalence across practices ranged from 35.8% for hypertension to 0.23% for Parkinson disease, with wide variability among practices for all conditions. Multimorbidity increased steeply with age, leveling off at age 80; overall, 45.2% of patients had more than one chronic illness.
  
  
  CONCLUSIONS
  Multimorbidity is a prevalent problem in primary care practice, a finding with implications for health care delivery and payment, quality assessment, and research.
authors.affiliation: Department of Family Medicine, Medical University of South Carolina, Charleston, SC 29425, USA. ornstesm@musc.edu
authors.forename: Steven M
authors.initials: SM
authors.lastname: Ornstein
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Nietert
authors.forename: Ruth G
authors.initials: RG
authors.lastname: Jenkins
authors.forename: Cara B
authors.initials: CB
authors.lastname: Litvin
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease / Q000453:epidemiology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011320:Primary Health Care / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: Chronic Disease; Morbidity; Practice-based Research; Primary Health Care