title: Prevalence of CKD and comorbid illness in elderly patients in the United States: results from the Kidney Early Evaluation Program (KEEP).
abstract: BACKGROUND
  Elderly individuals with chronic kidney disease (CKD) have high rates of comorbid conditions, including cardiovascular disease and its risk factors, and CKD-related complications. In individuals aged > or = 65 years, we sought to describe the prevalence of CKD determined from laboratory test results in the Kidney Early Evaluation Program (KEEP; n = 27,017) and National Health and Nutrition Examination Survey (NHANES) 1999-2006 (n = 5,538) and the prevalence of diagnosed CKD determined from billing codes in the Medicare 5% sample (n = 1,236,946). In all 3 data sources, we also explored comorbid conditions and CKD-related complications.
  
  
  METHODS
  CKD was identified as decreased estimated glomerular filtration rate (<60 mL/min/1.73 m(2)) or increased albumin-creatinine ratio in KEEP and NHANES; CKD was identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes in Medicare. Investigated comorbid conditions included diabetes, hypertension, high cholesterol level, coronary artery disease, congestive heart failure, cerebrovascular disease, peripheral vascular disease, and cancer, and CKD-related complications included anemia, hypocalcemia, hyperphosphatemia, and hyperparathyroidism.
  
  
  RESULTS
  The prevalence of CKD was approximately 44% in both KEEP and NHANES participants, and the prevalence of diagnosed CKD was 7% in Medicare beneficiaries. In all 3 data sets, the prevalence of CKD or diagnosed CKD was higher in participants aged > or = 80 years and those with comorbid conditions. For KEEP and NHANES participants, the prevalence of most comorbid conditions and CKD complications increased with decreasing estimated glomerular filtration rate. For participants with CKD stages 3-5, a total of 29.2% (95% CI, 27.8-30.6) in KEEP and 19.9% (95% CI, 17.0-23.1) in NHANES had anemia, 0.7% (95% CI, 0.4-0.9) and 0.6% (95% CI, 0.3-1.3) had hypocalcemia, 5.4% (95% CI, 4.7-6.1) and 6.4% (95% CI, 5.1-8.0) had hyperphosphatemia, and 52.0% (95% CI, 50.4-53.6) and 30.0% (95% CI, 25.9-34.3) had hyperparathyroidism, respectively.
  
  
  CONCLUSIONS
  CKD is common in the elderly population and is associated with high frequencies of concomitant comorbid conditions and biochemical abnormalities. Because CKD is not commonly diagnosed, greater emphasis on physician education may be beneficial.
authors.affiliation: Division of Nephrology, Tufts Medical Center, 800 Washington Street, Boston, MA 02111, USA. lstevens1@tuftsmedicalcenter.org
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Stevens
authors.forename: Suying
authors.initials: S
authors.lastname: Li
authors.forename: Changchun
authors.initials: C
authors.lastname: Wang
authors.forename: Cindy
authors.initials: C
authors.lastname: Huang
authors.forename: Bryan N
authors.initials: BN
authors.lastname: Becker
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Bomback
authors.forename: Wendy Weinstock
authors.initials: WW
authors.lastname: Brown
authors.forename: Nilka Ríos
authors.initials: NR
authors.lastname: Burrows
authors.forename: Claudine T
authors.initials: CT
authors.lastname: Jurkovitz
authors.forename: Samy I
authors.initials: SI
authors.lastname: McFarlane
authors.forename: Keith C
authors.initials: KC
authors.lastname: Norris
authors.forename: Michael
authors.initials: M
authors.lastname: Shlipak
authors.forename: Adam T
authors.initials: AT
authors.lastname: Whaley-Connell
authors.forename: Shu-Cheng
authors.initials: SC
authors.lastname: Chen
authors.forename: George L
authors.initials: GL
authors.lastname: Bakris
authors.forename: Peter A
authors.initials: PA
authors.lastname: McCullough
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000503:physiopathology; D015331:Cohort Studies; D003153:Community Health Services / Q000379:methods; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D005582:Foundations; D006801:Humans; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008403:Mass Screening / Q000379:methods; D015995:Prevalence; D013997:Time Factors; D014481:United States / Q000453:epidemiology