Cigarette smoking enhances increased urine albumin excretion as a risk factor for glomerular filtration rate decline in primary hypertension.
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.
Warmoth
Larry
L
Department of Internal Medicine, Texas Tech University Health Sciences Center, Texas Tech University School of Medicine, Lubbock, Texas 79430, USA.
Regalado
Monette M
MM
Simoni
Jan
J
Harrist
Ronald B
RB
Wesson
Donald E
DE
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*