title: Target renal damage: the microvascular associations of increased aortic stiffness in patients with COPD.
abstract: BACKGROUND
  Although renal impairment has been described in COPD, there is opportunity to evaluate further to determine nature and consider optimal management. Increased aortic stiffness, as seen in COPD, leads to reduced buffering of pulsatile flow. We hypothesised that urinary albumin creatinine ratio (UACR) would reflect glomerular damage related to aortic stiffness.
  
  
  METHODS
  Patients with COPD and controls underwent spirometry, blood pressure, arterial stiffness - aortic pulse wave velocity (PWV) and provided a spot urine sample for UACR, with other renal biomarkers measured.
  
  
  RESULTS
  The UACR was increased in patients (n = 52): 0.80 mg/mmol compared to controls (n = 34): 0.46 mg/mmol, p < 0.05. Aortic PWV was related to log10 UACR in all subjects (r = 0.426, p < 0.001) and COPD patients alone. Aortic PWV was a significant variable for UACR with oxygen saturations, after accounting for potential confounders. Eight subjects (7 patients) reached a defined clinical microalbuminuria threshold, with aortic PWV greater in these patients compared to those patients without, although albuminuria is a continuum. Proximal tubular damage biomarkers, unlike the glomerular marker, were not different between patients and controls.
  
  
  CONCLUSIONS
  There is glomerular damage in patients with COPD evidenced by increased UACR, related to increased aortic stiffness. Besides the macrovascular prognostic implications of increased aortic stiffness, the microvascular state in COPD management should be considered.
authors.affiliation: Nottingham Respiratory Research Unit, University of Nottingham, Clinical Sciences Building, City Hospital Campus, Hucknall road, Nottingham NG5 1PB, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: John
authors.forename: Samia
authors.initials: S
authors.lastname: Hussain
authors.forename: Andrew
authors.initials: A
authors.lastname: Prayle
authors.forename: Rebecca
authors.initials: R
authors.lastname: Simms
authors.forename: John R
authors.initials: JR
authors.lastname: Cockcroft
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Bolton
mesh_terms: D000419:Albuminuria / Q000175:diagnosis / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D007677:Kidney Function Tests / Q000379:methods; D008297:Male; D055806:Microvessels / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000652:urine*; D059289:Vascular Stiffness / Q000502:physiology*
chemical_list: D015415:Biomarkers; D003404:Creatinine