Prevalence of renal impairment and its association with cardiovascular risk factors in a general population: results of the Swiss SAPALDIA study.
BACKGROUND
Impaired renal function is evolving as an independent marker of the risk of cardiovascular morbidity and mortality. Little is known about the prevalence of impaired renal function and its relationship to cardiovascular risk factors in the Swiss general population.


METHODS
SAPALDIA comprises a random sample of the Swiss population established in 1991, originally to investigate the health effects of long-term exposure to air pollution. Participants were reassessed in 2002/3 and blood measurements were obtained (n = 6317). Renal function was estimated using the Cockcroft-Gault equation and the modified MDRD (four-component) equation incorporating age, race, gender and serum creatinine level.


RESULTS
The estimated prevalence of impaired renal function [estimated glomerular filtration rate <60 ml/min/1.73 m(2)] differed substantially between men and women, particularly at higher ages, and amounted to 13% [95% confidence interval (CI) 10-16%] and 36% (95% CI 32-40%) in men and women, respectively, of 65 years or older. Smoking, obesity, blood lipid levels, high systolic blood pressure and hyperuricaemia were all more common in men when compared with women. These cardiovascular risk factors were also associated independently with creatinine in both women and men. Women were less likely to receive cardiovascular drugs, in particular angiotensin-converting enzyme inhibitors and beta-blockers, when compared with men of the same age.


CONCLUSIONS
Moderate renal impairment seems to be prevalent in the general population, with an apparent excess in females which is not explained by conventional cardiovascular risk factors. The unexpected finding questions the validity of the prediction equations, in particular in females.
Nitsch
Dorothea
D
Department of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK. Dorothea.Nitsch@lshtm.ac.uk
Felber Dietrich
Denise
D
von Eckardstein
Arnold
A
Gaspoz
Jean-Michel
JM
Downs
Sara H
SH
Leuenberger
Philippe
P
Tschopp
Jean-Marie
JM
Brändli
Otto
O
Keller
Roland
R
Gerbase
Margaret W
MW
Probst-Hensch
Nicole M
NM
Stutz
Elisabeth Zemp
EZ
Ackermann-Liebrich
Ursula
U
D000368:Aged; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000453:epidemiology*; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051437:Renal Insufficiency / Q000453:epidemiology*; D012307:Risk Factors; D015996:Survival Rate; D013557:Switzerland / Q000453:epidemiology
D003404:Creatinine