title: Comorbidity and the use of primary care and specialist care in the elderly.
abstract: OBJECTIVE
  The impact of comorbidity on use of primary care and specialty services is poorly understood. The purpose of this study was to determine the relationship between morbidity burden, comorbid conditions, and use of primary care and specialist services
  
  
  METHODS
  The study population was a 5% random sample of Medicare beneficiaries, taken from 1999 Medicare files. We analyzed the number of ambulatory face-to-face patient visits to primary care physicians and specialists for each diagnosis, with each one first considered as the "main" one and then as a comorbid diagnosis to another. Each patient was categorized by extent of total morbidity burden using the Johns Hopkins Adjusted Clinical Group case-mix system.
  
  
  RESULTS
  Higher morbidity burden was associated with more visits to specialists, but not to primary care physicians. Patients with most diagnoses had more visits, both to primary care and specialist physicians for comorbid diagnoses than for the main diagnosis itself. Although patients, especially those with high morbidity burdens, generally made more visits to specialists than to primary care physicians, this finding was not always the case. For patients with 66 diagnoses, primary care visits for those diagnoses exceeded specialist visits in all morbidity burden groups; for patients with 87 diagnoses, specialty visits exceeded primary care visits in all morbidity burden groups.
  
  
  CONCLUSIONS
  In the elderly, a high morbidity burden leads to higher use of specialist physicians, but not primary care physicians, even for patients with common diagnoses not generally considered to require specialist care. This finding calls for a better understanding of the relative roles of generalists and specialists in the US health services system.
authors.affiliation: Department of Health Policy and Management, Johns Hopkins School of Public Health, Baltimore, MD 21205, USA. bstarfie@jhsph.edu
authors.forename: Barbara
authors.initials: B
authors.lastname: Starfield
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Lemke
authors.forename: Robert
authors.initials: R
authors.lastname: Herbert
authors.forename: Wendy D
authors.initials: WD
authors.lastname: Pavlovich
authors.forename: Gerard
authors.initials: G
authors.lastname: Anderson
mesh_terms: D000368:Aged; D015897:Comorbidity; D003953:Diagnosis-Related Groups; D006801:Humans; D006278:Medicare / Q000706:statistics & numerical data*; D008511:Medicine / Q000706:statistics & numerical data*; D009819:Office Visits / Q000706:statistics & numerical data; D011320:Primary Health Care / Q000706:statistics & numerical data*; D013038:Specialization; D014481:United States / Q000453:epidemiology