according to data from previous trials, and we wanted to
avoid possible side effects.
Methods
Study Design and Population
ASPIRANT (addition of spironolactone in patients with resistant
arterial hypertension) was an investigator-led, prospective, multi-
center, randomized, double-blind, placebo-controlled, parallel-group
trial. The design of the trial has been described previously.
14
We
enrolled patients older than 18 years with resistant arterial hyperten-
sion. Resistant hypertension was defined as office systolic BP
Ͼ140 mm Hg or diastolic BP Ͼ90 mm Hg despite being treated with
at least 3 antihypertensive drugs, including a diuretic. Patients with
diabetes or chronic kidney disease (defined as serum creatinine
Ͼ133
mol/L or proteinuria Ͼ300 mg/day) were enrolled if the
office BP was
Ͼ130/80 mm Hg.
The study was done in accordance with the principles of the Helsinki
declaration. The study protocol was approved by the ethical review
committees at all six participating secondary or tertiary care centers and
by the State Institute for Drug Control of the Czech Republic. Written
informed consent was obtained from all patients before enrollment. This
study was registered at clinicaltrials.gov as NCT00524615, and the
EudraCT number of the trial was 2007-003558-27.
For safety reasons, we excluded all patients with severe hypertension
(systolic BP
Ͼ180 mm Hg or diastolic BP Ͼ110 mm Hg) who needed
an immediate adjustment of treatment, renal insufficiency with serum
creatinine
Ͼ180
mol/L or glomerular filtration rate Ͻ40 mL/min
calculated by the Modification of Diet in Renal Disease formula,
15
hyperkalemia
Ͼ5.4 mmol/L, hyponatremia Ͻ130 mmol/L, and porphy-
ria; pregnant or lactating women or women of fertile age not using
effective contraception; and patients with known prior hypersensitivity
to the drug Verospiron (spironolactone; Richter Gedeon Ltd) or who are
currently using any aldosterone antagonist (spironolactone, eplerenone
or canreonate).
Procedures
Patients were randomly assigned in a 1:1 ratio to receive either
spironolactone at a dose of 25 mg once daily or a placebo once daily
in the morning, as an add-on to their current antihypertensive
therapy, by the method of simple randomization without stratifica-
tion. Patients received color-marked, blinded study therapy in a
random manner. The individual who prepared the blinded color-
marked containers of drugs was not otherwise connected to the
study, and all the investigators and patients were blinded to treatment
during the entire study period from September 25, 2007 until
October 5, 2010, when the randomization codes were opened. All the
study investigators deemed the blinding throughout the study as
adequate and sufficient.
After randomization, visits were scheduled at 4 and 8 weeks. In
patients with diabetes, patients older than 75 years, and patients with
serum creatinine
Ͼ133
mol/L, an additional safety visit was
performed 2 weeks after randomization. During every visit, office
BP was recorded by a calibrated mercury sphygmomanometer in
seated patients with their arm supported. The value was recorded as
the average of the second and third measurements with a minimum
delay of 3 minutes between the measurements. At baseline and 8
weeks, 24-hour ambulatory BP monitoring (ABPM) was performed
using validated devices.
16,17
Average daytime BP was calculated
from values measured between 9:00
AM
and 9:00
PM
, average
nighttime BP was calculated from values measured between 1:00 and
6:00
AM
, and average 24-hour BP was calculated from all the values
recorded by ABPM.
18
Serum sodium, potassium, chlorides, urea and creatinine, body
weight, and pulse were measured during every visit. Plasma renin
activity (PRA), plasma aldosterone and aldosterone/renin ratio
(ARR), microalbuminuria, and proteinuria in a 24-hour urine sample
were measured at baseline and at 8 weeks. The blood samples for
PRA and aldosterone were collected in the morning, after the
patients have been seated for 5 to 15 minutes, without discontinua-
tion of the medications.
19
Antihypertensive medications and all other
medications were recorded at baseline, and patients did not change
doses or the number of their antihypertensive medication throughout
the trial. At every visit, patients were asked about the occurrence of
any adverse effects of the medication. Compliance of patients was
assessed by the calculation of returned tablets.
According to study protocol, the administration of randomized
medication was to be terminated at any time in case of symptomatic
hypotension
Ͻ100/60 mm Hg, increase of serum potassium
Ͼ6.0 mmol/L, increase of serum creatinine Ͼ25% compared to baseline
and exceeding the upper reference limit of 104
mol/L, if the patient did
not tolerate the study medication because of side effects or any other
reason, or if the patient withdrew informed consent.
Our primary end points were to show a statistically significant
difference between the fall of average daytime systolic and diastolic
pressure on ABPM between the spironolactone and placebo groups after
8 weeks of treatment. The secondary end points were to show a
statistically significant difference in the fall of average 24-hour systolic
and diastolic BP and a difference in the fall of office BP between
spironolactone and a placebo during 8 weeks of treatments. Further
secondary end points were to compare the changes of serum levels of
sodium, potassium, serum creatinine, and body weight between treat-
ment groups and to evaluate the response to spironolactone treatment
based on the baseline aldosterone level and baseline ARR.
Statistical Analysis
Standard descriptive statistics were applied in the analysis. Contin-
uous variables were described using mean and SD when the
prerequisite of normality was fulfilled and using the median and 5th
and 95th percentile range in case of non-normal distribution. Cate-
gorical variables were described by the number of cases and the
percentages of categories. The statistical significance of differences
between study groups was analyzed using the Mann-Whitney U test
for continuous variables and the Fisher exact test for categorical
variables. Statistical analysis was computed using SPSS 18.0.2 (IBM
Corporation).
Power calculations were originally based on an expected average
difference of systolic BP fall between spironolactone and the placebo
of 10 mm Hg (SD 18.0 mm Hg) and a diastolic BP fall difference of
5 mm Hg (SD 10.7 mm Hg).
12
We needed a total of 102 patients to
have 90% power for systolic BP and 146 patients for diastolic BP at
P
Ͻ0.05. We expected about 90% randomized patients to complete
the trial and therefore decided to recruit 160 patients.
Role of the Funding Source
The study sponsors only provided financial support; they were not
involved in the study design; had no role in the collection, analysis,
or interpretation of the data; and were not involved in decisions about
its publication. J.V. had full access to all data and had final
responsibility for the decision to submit this paper for publication.
Results
The trial profile is shown in Figure 1. Patients were recruited
from September 2007 to June 2010, with follow-up during the 2
following months. Of the 168 screened patients, 117 (69.6%)
were eligible for enrollment, and 51 (30.4%) were not included
for reasons specified in Figure 1. The trial was stopped prema-
turely in accordance with the protocol after the first interim
analysis of the complete data of the 117 enrolled patients in
September 2010 showed a significant decrease of systolic BP in
one of the treatment arms, together with a much lower than
expected decrease of diastolic BP. An updated power analysis
with actual study data of diastolic BP showed that we would
need a total of 282 patients in both arms finishing the trial to
reach P
Ͻ0.05 for daytime ABPM diastolic BP.
Baseline characteristics were well matched between the
treatment groups in baseline demographic characteristics,
1070
Hypertension
June 2011
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