title: Geographic variation in diagnosis frequency and risk of death among Medicare beneficiaries.
abstract: BACKGROUND
  Because diagnosis is typically thought of as purely a patient attribute, it is considered a critical factor in risk-adjustment policies designed to reward efficient and high-quality care.
  
  
  OBJECTIVE
  To determine the association between frequency of diagnoses for chronic conditions in geographic areas and case-fatality rate among Medicare beneficiaries.
  
  
  METHODS
  Cross-sectional analysis of the mean number of 9 serious chronic conditions (cancer, chronic obstructive pulmonary disease, coronary artery disease, congestive heart failure, peripheral artery disease, severe liver disease, diabetes with end-organ disease, chronic renal failure, and dementia) diagnosed in 306 hospital referral regions (HRRs) in the United States; HRRs were divided into quintiles of diagnosis frequency. Participants were 5,153,877 fee-for-service Medicare beneficiaries in 2007.
  
  
  METHODS
  Age/sex/race-adjusted case-fatality rates.
  
  
  RESULTS
  Diagnosis frequency ranged across HRRs from 0.58 chronic conditions in Grand Junction, Colorado, to 1.23 in Miami, Florida (mean, 0.90 [95% confidence interval {CI}, 0.89-0.91]; median, 0.87 [interquartile range, 0.80-0.96]). The number of conditions diagnosed was related to risk of death: among patients diagnosed with 0, 1, 2, and 3 conditions the case-fatality rate was 16, 45, 93, and 154 per 1000, respectively. As regional diagnosis frequency increased, however, the case fatality associated with a chronic condition became progressively less. Among patients diagnosed with 1 condition, the case-fatality rate decreased in a stepwise fashion across quintiles of diagnosis frequency, from 51 per 1000 in the lowest quintile to 38 per 1000 in the highest quintile (relative rate, 0.74 [95% CI, 0.72-0.76]). For patients diagnosed with 3 conditions, the corresponding case-fatality rates were 168 and 137 per 1000 (relative rate, 0.81 [95% CI, 0.79-0.84]).
  
  
  CONCLUSIONS
  Among fee-for-service Medicare beneficiaries, there is an inverse relationship between the regional frequency of diagnoses and the case-fatality rate for chronic conditions.
authors.affiliation: Department of Veterans Affairs Medical Center, White River Junction, Vermont, USA. h.gilbert.welch@dartmouth.edu
authors.forename: H Gilbert
authors.initials: HG
authors.lastname: Welch
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Sharp
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Gottlieb
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Skinner
authors.forename: John E
authors.initials: JE
authors.lastname: Wennberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease / Q000401:mortality*; D003430:Cross-Sectional Studies; D003933:Diagnosis; D018588:Fee-for-Service Plans / Q000706:statistics & numerical data; D005260:Female; D005843:Geography; D006801:Humans; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D009026:Mortality / Q000639:trends*; D017063:Outcome Assessment, Health Care; D011787:Quality of Health Care; D012306:Risk; D014481:United States / Q000453:epidemiology