Ambulatory blood pressure trajectories and blood pressure variability in kidney transplant recipients: a comparative study against haemodialysis patients

Abstract

Background Hypertension is the most prevalent cardiovascular risk factor in kidney-transplant-recipients (KTRs). Preliminary data suggest similar ambulatory-blood-pressure (ΒP) levels in KTRs and hemodialysis (HD) patients. This is the first study evaluating in comparison the full ambulatory-BP-profile and short-term BP-variability (BPV) in KTRs versus HD patients. Methods Two-hundred-four KTRs were matched (2:1 ratio) with 102 HD patients for age and gender. BP-levels, BP-trajectories and BPV indices over a 24-hour ambulatory-BP-monitoring (ABPM) in KTRs were compared against both the 1st and 2nd 24-hour period of a standard 48-hour ABPM in HD. To evaluate the effect of renal-replacement-treatment and time on ambulatory-BP-levels, two-way-ANOVA for repeated-measurements was performed. Results KTRs had significantly lower SBP and pulse-pressure (PP) levels compared to HD during all periods studied (24-hour SBP: KTR: 126.5 ± 12.1mmHg; HD 1st 24-hour: 132.0 ± 18.1mmHg, p = 0.006; 2nd 24-hour: 134.3 ± 17.7mmHg, p < 0.001); no significant differences were noted for DBP levels with the exception of 2nd nighttime. Repeated-measurements-ANOVA showed a significant effect of RRT modality and time on ambulatory-SBP-levels during all periods studied, and a significant interaction between-them; the greatest between-group difference in BP (KTRs—HD in mmHg) was observed at the end of the 2nd 24-hour (-13.9mmHg, 95%CI: -21.5 to -6.2, p < 0.001). Ambulatory systolic and diastolic BPV indices were significantly lower in KTRs than in HD during all periods studied (24-hour SBP-ARV: KTRs: 9.6 ± 2.3mmHg; HD 1st 24-hour: 10.3 ± 3.0mmHg, p = 0.032; 2nd 24-hour: 11.5 ± 3.0mmHg, p < 0.001). No differences were noted in dipping pattern between the two groups. Conclusions SBP and PP levels and trajectories, and BPV were significantly lower in KTRs compared to age- and gender-matched HD patients during all periods studied. These findings suggest a more favorable ambulatory-BP-profile in KTRs, in contrast to previous observations.

Ambulatory blood pressure trajectories and blood pressure variability in kidney transplant recipients: a comparative study against chronic kidney disease patients

“…This is the first study to compare short-term BPV between KTRs and CKD patients without kidney replacement therapy, showing no significant differences between the two study groups in all indices studied except for DBP SD. Based on these observations and previous findings that KTRs have significantly lower BPV compared with hemodialysis individuals [ 25 ], one could hypothesize that BPV levels are improved after kidney transplantation to a level comparable to that of CKD patients without kidney replacement therapy with similar eGFR. Possible explanations for this improvement include BP lowering and downregulation of sympathetic nervous system overdrive observed after kidney transplantation [ 31 ].…”

“…To the best of our knowledge, studies comparing mean ambulatory BP values between KTRs and CKD patients (including both CKD patients without kidney replacement therapy and individuals undergoing hemodialysis) are scarce. Α few studies comparing KTRs and hemodialysis patients with ABPM showed that both groups generally display similar BP levels [ 23 , 24 ]; however, in a recent study by our group, which is currently the largest in the field, SBP and PP levels were significantly lower in KTRs compared to hemodialysis patients, and BP trajectories differed accordingly [ 25 ]. With regards to CKD patients without kidney replacement therapy, in the only study to date comparing the mean ambulatory BP values between 92 KTRs and 97 CKD patients, 24-hour SBP, as well as awake and sleep SBP were significantly higher in KTRs, while office BP was not [ 14 ].…”

“…Ozkayar et al [ 30 ] have previously shown that KTRs with endothelial dysfunction have significantly higher BPV compared to those without endothelial dysfunction. In a recent case-control study of our group in 204 KTRs and 102 matched for age and sex hemodialysis patients, we showed that KTRs have significantly lower short-term BPV compared to their hemodialysis counterparts [ 25 ]. This is the first study to compare short-term BPV between KTRs and CKD patients without kidney replacement therapy, showing no significant differences between the two study groups in all indices studied except for DBP SD.…”

A parallel evaluation of short- and mid-term changes of ambulatory blood pressure in kidney transplant recipients and kidney donors

“…The dipping pattern of nocturnal BP was calculated with the following formula: 1 − mean night/mean day ratio of systolic BP (SBP) (%). Patients were categorized into four groups: extreme dippers (nocturnal BP decrease of >20%), dippers (decrease of >10% but ≤20%), non-dippers (decrease of ≥0% but ≤10%) and reverse dippers (nocturnal increase in SBP) [ 19 ]. The pre-awakening morning SBP surge was calculated as the difference between the average of the 2 h after awaking minus the average of the 2 h pre-awakening, as previously described [ 28 ].…”

“…Current literature suggests that KTx is associated with improved BP levels in transplant recipients compared with the pre-transplant condition [ 17 , 18 ] or patients on dialysis [ 19 ]. In addition, BP levels in kidney donors do not appear to change significantly after renal transplantation [ 20–23 ].…”