title: Hypertensive/Microvascular Disease and COPD: a Case Control Study.
abstract: OBJECTIVE
  This study tested the hypothesis that individuals with chronic obstructive pulmonary disease (COPD) have more small vessel disease and more severe disease than an age- and gender- matched hospital patient comparison group.
  
  
  METHODS
  This was a single centre, case-control study of 151 individuals with COPD (FEV1/VC) < 0.7 recruited consecutively immediately after respiratory function tests at a Melbourne teaching hospital over a 4 month period in 2010. Controls were individuals with normal respiratory function tests recruited contemporaneously from the same centre. Retinal images were obtained with a nonmydriatic camera (KOWA or Canon CR5-45NM), deidentiifed and graded by two trained graders for microvascular retinopathy (Wong and Mitchell classification), and vessel calibre using a computer-assisted method and Knudtson's modification of the Parr-Hubbard formula. Differences in microvascular retinopathy and vessel calibre between COPD patients and the comparison group were examined using Fisher's exact test or the t test (StataCorp, Texas).
  
  
  RESULTS
  Patients with COPD had more microvascular retinopathy (121, 80% and 76, 50%; OR 3.98, 95%CI 2.39 to 6.64) and more severe disease (42, 28% and 18, 12%; OR 2.85, 95% CI 1.55 to 5.23) than other hospital patients. COPD remained an independent determinant of microvascular retinopathy (OR 4.56, 95%CI 2.49 to 8.36) after adjusting for gender, hypertension, smoking, and diabetes duration. Retinal arterioles and venules were wider in patients with COPD than other hospital patients (mean difference +6.5 µm, 95% confidence interval 1.4 to 11.6; and +17.4 µm, 95%CI 9.4 to 25.5, respectively). Larger venules were more common in younger individuals (+0.6 µm, 0.1 to 1.17) with more cigarette exposure (+0.3 µm, 0.2 to 0.5) or a lower serum albumin (+23.0 µm, 6.0 to 40.0). Venular calibre was not different in current and former smokers (p=0.77). There were trends for venules to be larger with more severe COPD (lower FEV1/VC, p=0.09) and with CT-demonstrated emphysema (p=0.06).
  
  
  CONCLUSIONS
  Hypertensive/microvascular disease is more common and more severe in patients with COPD. This is likely to contribute to the associated increase in cardiac risk.
authors.affiliation: The University of Melbourne Department of Medicine (Northern Health), Epping, Australia.
authors.forename: Sky K H
authors.initials: SK
authors.lastname: Chew
authors.forename: Deb
authors.initials: D
authors.lastname: Colville
authors.forename: Piers
authors.initials: P
authors.lastname: Canty
authors.forename: Anastasia
authors.initials: A
authors.lastname: Hutchinson
authors.forename: Alex
authors.initials: A
authors.lastname: Wong
authors.forename: Vi
authors.initials: V
authors.lastname: Luong
authors.forename: Tien Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Christine
authors.initials: C
authors.lastname: McDonald
authors.forename: Judy
authors.initials: J
authors.lastname: Savige
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D055806:Microvessels / Q000473:pathology*; D008875:Middle Aged; D010865:Pilot Projects; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D012164:Retinal Diseases / Q000175:diagnosis* / Q000453:epidemiology; D012171:Retinal Vessels / Q000473:pathology*; D012307:Risk Factors