Microalbuminuria may predict renal and cardiovascular disease in patients with hypertension but without diabetes, according to the results of a study reported online April 29 in the Clinical Journal of the American Society of Nephrology.

“Our findings emphasize the usefulness of a more widespread evaluation of microalbuminuria in an effort to guide the management of hypertension,” said senior author Roberto Pontremoli, MD, PhD, from the University of Genoa in Genoa, Italy, in a news release.

“Increased urinary albumin excretion is a known risk factor for cardiovascular events and clinical nephropathy in patients with diabetes,” the study authors write. “Whether microalbuminuria predicts long-term development of chronic renal insufficiency (CRI) in patients without diabetes and with primary hypertension remains to be documented.”

The investigators performed an 11.8-year follow-up of 917 patients with hypertension but without diabetes (total follow-up, 10,268 person-years) who were enrolled in the Microalbuminuria: A Genoa Investigation on Complications (MAGIC) cohort between 1993 and 1997. At baseline, untreated patients underwent testing of urinary albumin-to-creatinine ratio (ACR) for determination of microalbuminuria, defined as an ACR of at least 22 mg/g in men and an ACR of at least 31 mg/g in women.

Microalbuminuria at baseline was associated with an increased risk during follow-up for the development of CRI (relative risk [RR], 7.61; 95% confidence interval [CI], 3.19 - 8.16; P < .0001), cardiovascular events (defined as a composite of fatal and nonfatal cardiac and cerebrovascular events; RR, 2.11; 95% CI, 1.08 - 4.13; P < .028), and cardiorenal events (defined as a composite of these other endpoints; RR, 3.21; 95% CI, 1.86 - 5.53; P < .0001).

After adjustment for several baseline covariates, including age, body mass index, blood pressure, cholesterol level, and renal function, microalbuminuria continued to be significantly associated with CRI (RR, 12.75; 95% CI, 3.62 - 44.92; P < .0001) and cardiorenal events (RR, 2.58; 95% CI, 1.32 - 5.05; P < .0056).

"Microalbuminuria is an independent predictor of renal and cardiovascular complications in patients without diabetes and with primary hypertension," the study authors write.

Limitations of this study include possible underestimation of the prevalence of new-onset CRI and of the association between microalbuminuria and cardiovascular and renal endpoints. In addition, estimated glomerular filtration rate (eGFR) by use of equations has a certain degree of inaccuracy, and there are no definitive data regarding the relationship between cardiovascular and renal risk associated with microalbuminuria based on the type of treatment or on blood pressure control.

"Patients with microalbuminuria should be aggressively targeted for renal and cardiovascular risk factor reduction, although further research is warranted to determine whether specific treatment would help to improve outcomes, as already reported for patients with diabetes," the study authors conclude.

The study authors have disclosed no relevant financial relationships.

Clin J Am Soc Nephrol. Published online April 29, 2010. Abstract