title: Cigarette smoking enhances increased urine albumin excretion as a risk factor for glomerular filtration rate decline in primary hypertension.
abstract: BACKGROUND
  Subjects with severe compared with mild primary hypertension are at greater risk for decline in glomerular filtration rate (GFR), but additional risk factors are poorly defined.
  
  
  METHODS
  Seventy-five subjects referred for assistance with blood pressure control ("severe") and 150 not-referred hypertensive subjects ("mild") were prospectively followed for 7 years. The primary outcome was the change in calculated GFR during follow-up as predicted by various clinical parameters, including urine albumin excretion measured as urine albumin (mg)-to-creatinine (g) (alb/cr) ratio.
  
  
  RESULTS
  Calculated GFR declined faster (more negative slope) in patients with severe hypertension than in those with mild hypertension (-0.188+/- 0.025 versus -0.120+/- 0.008 mL/min/month; P=0.010), despite similar follow-up systolic blood pressure (133.4+/-1.2 versus 131.9+/-0.8 mm Hg). Severe subjects had higher entry alb/cr (241.3+/- 29.1 versus 11.4+/- 0.5) and a greater proportion of cigarette smokers than mild subjects (56 versus 19%). Regression analysis comparing GFR decline to alb/cr showed that GFR changed minimally for alb/cr up to 200 but declined at a progressively faster rate as alb/cr increased above 200. GFR declined faster (more negative slope) in smokers than in nonsmokers (-0.231+/- 0.023 versus -0.102+/- 0.008 mL/min/month; P<0.001). Cigarette smoking increased the risk for GFR decline in subjects with alb/cr <200 and in those with alb/cr >200, but the effect was much more robust for subjects with alb/cr >200.
  
  
  CONCLUSIONS
  Urine alb/cr >200 increases the risk for subsequent GFR decline in primary hypertension, and this risk is enhanced by cigarette smoking.
authors.affiliation: Department of Internal Medicine, Texas Tech University Health Sciences Center, Texas Tech University School of Medicine, Lubbock, Texas 79430, USA.
authors.forename: Larry
authors.initials: L
authors.lastname: Warmoth
authors.forename: Monette M
authors.initials: MM
authors.lastname: Regalado
authors.forename: Jan
authors.initials: J
authors.lastname: Simoni
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Harrist
authors.forename: Donald E
authors.initials: DE
authors.lastname: Wesson
mesh_terms: D000419:Albuminuria / Q000652:urine*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*