title: Baseline characteristics of patients with chronic kidney disease stage 3 and stage 4 in Spain: the MERENA observational cohort study.
abstract: BACKGROUND
  To obtain information on cardiovascular morbidity, hypertension control, anemia and mineral metabolism based on the analysis of the baseline characteristics of a large cohort of Spanish patients enrolled in an ongoing prospective, observational, multicenter study of patients with stages 3 and 4 chronic kidney diseases (CKD).
  
  
  METHODS
  Multicenter study from Spanish government hospital-based Nephrology outpatient clinics involving 1129 patients with CKD stages 3 (n = 434) and 4 (n = 695) defined by GFR calculated by the MDRD formula. Additional analysis was performed with GFR calculated using the CKD-EPI and Cockcroft-Gault formula.
  
  
  RESULTS
  In the cohort as a whole, median age 70.9 years, morbidity from all cardiovascular disease (CVD) was very high (39.1%). In CKD stage 4, CVD prevalence was higher than in stage 3 (42.2 vs 35.6% p < 0.024). Subdividing stage 3 in 3a and 3b and after adjusting for age, CVD increased with declining GFR with the hierarchy (stage 3a < stage 3b < stage 4) when calculated by CKD-EPI (31.8, 35.4, 42.1%, p 0.039) and Cockcroft-Gault formula (30.9, 35.6, 43.4%, p 0.010) and MDRD formula (32.5, 36.2, 42.2%,) but with the latter, it did not reach statistical significance (p 0.882). Hypertension was almost universal among those with stages 3 and 4 CKD (91.2% and 94.1%, respectively) despite the use of more than 3 anti-hypertensive agents including widespread use of RAS blockers. Proteinuria (> 300 mg/day) was present in more than 60% of patients and there was no significant differences between stages 3 and 4 CKD (1.2 ± 1.8 and 1.3 ± 1.8 g/day, respectively). A majority of the patients had hemoglobin levels greater than 11 g/dL (91.1 and 85.5% in stages 3 and 4 CKD respectively p < 0.001) while the use of erythropoiesis-stimulating agents (ESA) was limited to 16 and 34.1% in stages 3 and 4 CKD respectively. Intact parathyroid hormone (i-PTH) was elevated in stage 3 and stage 4 CKD patients (121 ± 99 and 166 ± 125 pg/mL p 0.001) despite good control of calcium-phosphorus levels.
  
  
  CONCLUSIONS
  This study provides an overview of key clinical parameters in patients with CKD Stages 3 and 4 where delivery or care was largely by nephrologists working in a network of hospital-based clinics of the Spanish National Healthcare System.
authors.affiliation: Nephrology Unit, Hospital Universitario Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain. albertomcastelao@gmail.com
authors.forename: Alberto
authors.initials: A
authors.lastname: Martínez-Castelao
authors.forename: José L
authors.initials: JL
authors.lastname: Górriz
authors.forename: José M
authors.initials: JM
authors.lastname: Portolés
authors.forename: Fernando
authors.initials: F
authors.lastname: De Alvaro
authors.forename: Aleix
authors.initials: A
authors.lastname: Cases
authors.forename: José
authors.initials: J
authors.lastname: Luño
authors.forename: Juan F
authors.initials: JF
authors.lastname: Navarro-González
authors.forename: Rafael
authors.initials: R
authors.lastname: Montes
authors.forename: Juan J
authors.initials: JJ
authors.lastname: De la Cruz-Troca
authors.forename: Aparna
authors.initials: A
authors.lastname: Natarajan
authors.forename: Daniel
authors.initials: D
authors.lastname: Batlle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000453:epidemiology / Q000378:metabolism; D000959:Antihypertensive Agents / Q000627:therapeutic use; D002118:Calcium / Q000097:blood; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006977:Hypertension, Renal / Q000188:drug therapy / Q000453:epidemiology; D007501:Iron / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000378:metabolism; D009017:Morbidity; D010758:Phosphorus / Q000097:blood; D011507:Proteinuria / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology*; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology*; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000959:Antihypertensive Agents; D008903:Minerals; D010758:Phosphorus; D007501:Iron; D002118:Calcium