Microalbuminuria Linked to
Cardiac Risk in Hypertensive Patients
The detection of microalbuminuria in
hypertensive patients may help the clinician
decide when to start therapy.
Microalbuminuria is associated with cardiac
risk in hypertensive patients with left
ventricular hypertrophy (LVH), according to the
results of the prospective Losartan Intervention
For Endpoint reduction (LIFE) study published in
the Dec. 2 issue of the Annals of Internal
Medicine. The investigators suggest that.
"Several studies have shown that
albuminuria is associated with increased risk
for fatal and nonfatal cardiovascular events,
independent of conventional risk factors,"
write Kristian Wachtell, MD, PhD, from Glostrup
University Hospital in Denmark, and colleagues.
"The partition values for urine albumin–creatinine
ratio (UACR) used to identify microalbuminuria
have been based on studies that predicted risk
in diabetic patients."
In this multicenter cohort study derived from
a randomized controlled trial, 8,206 patients
with stage II or III hypertension were
randomized to receive double-blind therapy with
losartan or atenolol and were followed for
39,122 patient-years. Renal glomerular
permeability was evaluated by UACR.
With increasing albuminuria, the risk for the
composite cardiovascular end point increased
continuously in nondiabetic hypertensive
patients with LVH (P < .001 for
trend). There was no specific threshold for
increased risk. With every 10-fold increase in
UACR, there were increases in hazard ratio for
composite end point (by 57%; 95% confidence
interval [CI], 40.6% - 75.0%); cardiovascular
mortality (97.7%; 95% CI, 66.5% - 235%);
all-cause mortality (75.2%; 95% CI, 54.0% -
99.4%); stroke (51.0%; 95% CI, 28.8% - 76.9%);
and myocardial infarction (45%; 95% CI, 19.9% -
75.4%; P < .001 for all).
Although hazard ratios were similar in
diabetic patients, the trend was weaker and not
significant for myocardial infarction.
"Increased UACR resulted in increasing
risk for cardiovascular morbidity and mortality
among hypertensive patients with LVH," the
authors write. "We found no thresholds or
plateaus. Risk increases at much lower UACR
values than has been reported among diabetic
patients."
Study limitations include measurement of UACR
in a single spot urine collection, determination
of LVH by ECG alone, possible confounding
factors not considered in the Framingham risk
score, and inability to generalize beyond a
cohort of patients selected by the LIFE study
criteria and treated according to the LIFE study
protocol.
"Microalbuminuria assessment in
hypertensive patients improves cardiovascular
risk stratification," the authors write.
"Detecting microalbuminuria might also help
the clinician decide when to initiate
antihypertensive therapy because identification
of target organ damage is an indication for
treatment in patients with lower blood
pressure." Ann Intern Med.
2003;139:901-906
