64
urinary albumin. After a median follow-up of 4.9 years, 72 patients (13.6%) died,
and there were 96 cardiovascular events. After adjustment for several cardiovascu-
lar risk factors, baseline albuminuria, either as a continuous variable or categorized
at different cutoff values, was an independent predictor of the composite outcome
of all-cause and cardiovascular mortality, strokes, and coronary events. Each ten-
fold increase in 24-h urinary albumin conferred a 1.5- to twofold higher risk of each
component of the composite outcome. Serial changes in microalbuminuria status
during follow-up reflected changes in cardiovascular risk. Reduction of microalbu-
minuria was associated with a 27% lower risk of cardiovascular events compared to
a 65% increased risk associated with increased microalbuminuria. This study dem-
onstrated the prognostic effect of microalbuminuria in a cohort with RH. The
authors suggested that microalbuminuria reduction may be an important surrogate
target in treatment of RH.
It has been recognized that 10–20% of a population with normal office BP have
isolated ambulatory hypertension (masked hypertension). Recent meta-analyses
report a prevalence of masked hypertension of 17% in a general hypertensive popu-
lation of 25,629 patients [ 22 ] and 8% in 980 patients with CKD stages 2 to 4 [ 2 ].
More recent data in 333 predominantly male veterans with a mean age of 70 and
CKD stages 2 to 4, suggested higher prevalence of masked hypertension in CKD of
between 27% and 56% depending on whether daytime, nighttime, or average ambu-
latory BP was used as a diagnostic criterion [ 23 ]. The Uppsala Longitudinal Study
of Adult Men was the first major study to describe clinical outcomes in masked
hypertension in 578 men aged 70 years that did not take antihypertensive drugs
[ 24 ]. Of these, 188 (33%) were normotensive by both office and ambulatory
BP. Eighty-two (14%) showed masked hypertension, whereas 308 (53%) subjects
had sustained hypertension by both office and ambulatory BP. Plasma glucose lev-
els, measures of abdominal obesity, and left ventricular wall thickness were
increased at baseline in subjects with isolated ambulatory hypertension. Seventy-
two cardiovascular morbid events occurred over 8.4 years of follow-up. The prog-
nostic value of isolated ambulatory and sustained hypertension was assessed with
Cox proportional hazard regression adjusting for serum cholesterol, smoking, and
diabetes. Isolated ambulatory hypertension was associated with a nearly threefold
increased risk of cardiovascular morbidity compared to the normotensive group
(HR, 2.8; 95% CI, 1.3–6.7) with a similar prognosis to sustained hypertension (HR,
2.9; 95% CI, 1.5–5.8). While the latter study described clinical outcomes in elderly
men with untreated hypertension, a subsequent prospective study described progno-
sis of masked hypertension in 742 treated hypertensives [ 13 ]. The groups were clas-
sified by ABPM into responder (normal clinic and ambulatory BP, n = 340), masked
(normal clinic but high ambulatory BP, n = 126), pseudoresistant (high clinic but
normal ambulatory BP, n = 146), and true RH (high clinic and ambulatory BP,
n = 130). In this study, a clinic BP of <140/90 mmHg and daytime ambulatory BP
<135/85 mmHg was considered normal. No assessment of drug compliance was
reported, and it was not specified whether the minimum of three antihypertensive
drugs in the group with true RH included diuretics. Compared to the responder
group, the true RH group had greater baseline end-organ damage with more preva-
A. Odudu et al.