COMPARATIVE ANALYSIS OF HYPERTENSION AND ITS CAUSES
AMONG RENAL REPLACEMENT THERAPY PATIENTS
Summary
Background
Life prolongation of patients with chronic kidney disease (CKD) treated
conservatively or after renal replacement therapy (RRT) increases the time of exposure to
harmful factors related to lifestyle, environment and treatments leading to the prevalence of
cardiovascular diseases (CVD. In renal replacement therapy (RRT) patients, the target values
of blood pressure (BP) are being continuously modified and excessive fat tissue may even
have a protective impact on the risk of mortality due to cardiovascular causes – the “obesity
paradox”. Automatic 24-h ambulatory blood pressure monitoring (ABPM) enables credible
and precise comparison of BP values and 24-h BP circadian rhythm between patients
undergoing hemodialysis (HD), peritoneal dialysis (PD) and post- kidney transplant (KTx).
The measurement enables 24-h recording of BP values during taking of the patient’s daily
vital functions. The health-related quality of life (HRQoL) may determine the efficacy of
RRT.
Purpose
The purpose of this study was to compare the occurrence of arterial hypertension
(HTN) and its underlying causes in patients in the first year after KTx, and in HD or PD
patients.
Material and Methods
A group of 120 RRT patients (PD, n=30; HD, n=40; KTx, n=50) was analyzed. The
following research tools were used: (1) 24- or 44-h ambulatory blood pressure monitoring
(ABPM); (2) bioelectrical impedance analysis (BIA); (3) traditional method – office BP; (4)
Morisky-Green test; and (5) disease history; (6) Medical Outcomes Study 36 - the Short Form
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(SF-36v.1); (7) Kidney Disease Quality of Life Short Form (KDQOL-SF™ v1.3). The
significance level was p<0.05.
Results
The results demonstrate that the HTN prevalence in patients in the 3rd month after
KTx stands at 85% did not change over the follow-up period of 12 months. The efficacy of
anti-hypertensive pharmacotherapy had changed slightly – 38% in the 12th month after KTx
vs. 33% in the 3rd month after KTx. In patients in the 12th month after KTx, as opposed to
patients in the 3rd month after KTx, BP values went up along with increased creatinine
concentration (r=0.38; p<0.05). The correlation between urine protein presence and BP was
similar (r=0.38; p<0.05). In patients in the 12 month after KTx, a positive correlation of
hemoglobin concentration with BP (r=0.31; p<0.05) was shown. Comparing dipping in the
3rd and 12th month after KTx, we found a rise in the frequency of at least 10% of the drop of
night-time BP in favor of patients in the 12th month after KTx (16% vs. 40%; p< 0.05).
HD patients showed the statistically significant impact of fat tissue growth on reducing
BP. The cardioprotective nature of the fat tissue concerned both the whole body fat (r=–0.34;
p<0.05) and abdominal fat (r=–0.44; p<0.05). Fat-free body mass corresponding to the
skeletal muscle protein mass expressed as FFMI demonstrated a negative correlation with BP
(r=–0.35; p<0.05), which proves the cardioprotective role of muscle mass in HTN
development. A clinically significant correlation revealed that the increase in the pre-dialysis
creatinine concentration reduced BP (r=–0.22; NS). This also indirectly endorses the
protective role of muscle mass in HTN pathogenesis.
Our study revealed HTN (on a basis of ABPM values and anti-hypertensive treatment)
in 90% of PD patients, in 83% of HD patients in the first 24 h after hemodialysis, and in 95%
of HD patients in the second 24 h after hemodialysis. In own study, no impact of Kt/V and
URR on BP of HD patients has been shown. Among HD patients, the following conversion
was demonstrated: from non-dipping in the first 24 h to inverse-dipping in the second 24 h of
the interdialytic period (45% vs. 64%; p<0.05).
Among PD patients, along with increasing differences between measured TBW and
iTBW, BP was increasing (r=0.40; p<0.05). We showed the cardioprotective nature of the
acid-base balance. Along with the balancing of chronic metabolic acidosis (increased
stHCO3), BP decreased (r=–0.41, p<0.05)
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An analysis of correlation in RRT groups demonstrated that Physical Component
Summary (PCS) was significantly statistically correlated with the following: SBP (r=–0.54;
p<0.05), DBP (r=–0.58; p<0.05) and creatinine concentration (r=–0.46; p<0.05) in the 12th
month after KTx; hematocrit (r=0.40; p<0.05), hemoglobin concentration (r=0.24; p<0.05)
among HD patients; SBP (r=–0.70; p<0.05), DBP (r=–0.40; p<0.05), age (r=0.68; p<0.05),
BMI (r=–0.74; p<0.05), creatinine concentration (r=0.41; p<0.05), total cholesterol
concentration (r=0.57; p<0.05), and LDL concentration (r=0.54; p<0.05) among PD patients.
Conclusions
1. The results of the study show insufficient monitoring of arterial hypertension in RTRs.
2. Fat tissue plays a cardioprotective role in the development of hypertension in HD
patients.
3. The transplanted kidney function parameters (creatinine, urine protein presence)
demonstrate positive correlation with ABPM in the 12th month after KTx. This shows
the possibility of early identification of patients exposed to development of chronic
allograft nephropathy.
4. HRQOL of ESRD patients differed depending on the RRT method used: highest
values were shown by post-KTx patients, lower values by PD patients, and the lowest
ones by HD patients.
5. Along with patient age, increased BP, and BMI, a drop in value of HRQOL in post-Tx
or PD patients was observed.
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