Σμαράγδη Μαρινάκη, Επίκουρη Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Ι.Ν. Μπολέτης, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παντελής Σαραφίδης, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΑΠΘ
Background: Kidney transplantation is the treatment of choice for patients with ESRD, associated with improved survival and better quality of life in relation to hemodialysis or peritoneal dialysis. However, cardiovascular mortality in transplanted patients remains much higher than that in general population. Hypertension is a major risk factor for cardiovascular disease in renal transplant recipients, as it has a high prevalence (70-95%) and is associated with both poor graft survival and reduced life expectancy. However, several studies have demonstrated that adequate control of blood pressure is often not achieved in transplanted patients. Therefore, precise recording of blood pressure becomes particularly important. To date, a limited number of studies provide sufficient data on the role of ambulatory blood pressure monitoring (ABPM) in the diagnosis, prognosis, control and treatment of hypertension in renal transplant recipients.
Methods: We performed a cross-sectional study in a cohort of 150 stable renal transplant recipients, to whom office BP (oBP) measurements and 24-hr ambulatory blood pressure monitoring (ABPM) using Mobil-O-Graph-NG device (ΙΕΜ Stoldberg, GER) were performed. Arterial hypertension was defined as: (1) office BP (oBP) ≥140/90 mmHg or use of antihypertensive agents, (2) ambulatory BP ≥130/80 mmHg or use of antihypertensive agents. Awareness of arterial hypertension was determined by the percentage of patients aware of arterial hypertension diagnosis according to their past medical history. Adequate control was defined as oBP <140/90 or 24-hr BP <130/80 mmHg. Patterns of BP control were defined as follows: (1) true BP control (oBP <140/90 and 24-hr BP <130/80mmHg), (2) true uncontrolled hypertension (oBP ≥140/90 and 24-hr BP ≥130/80mmHg), (3) white-coat hypertension (oBP ≥140/90 and 24-hr BP <130/80mmHg), (4) masked hypertension (oBP <140/90 and 24-hr BP ≥130/80mmHg).
Results: Prevalence of hypertension was very high (94%) according to ABPM data and 88.7% according to oBP measurements, with moderate agreement of the two techniques (κ-statistics =0.499, p<0,001). In all, 126 participants were receiving antihypertensive treatment. Οnly 4.7% of the transplanted patients were categorized as normotensives, while 31.5% of the hypertensives had true controlled hypertension confirmed by both the two BP techniques and 20.3% had true uncontrolled hypertension with both techniques. Moreover, the prevalence of white-coat hypertension was 7% and that of masked hypertension was 41.2%. In hypertensive patients, oBP ≥140/90 mmHg had 33% sensitivity and 83.9% specificity for the diagnosis of 24-hr BP ≥130/80mmHg. The positive and negative predictive value were 74.4% and 46.8% respectively. Finally, when comparing the prevalence and control of hypertension according to the definitions of the European Society of Cardiology (ESC)-European Society of Hypertension (ESH) and American College of Cardiology (ACC)-American Heart Association (AHA), the prevalence of hypertension did not differ significantly based on the two definitions (88.7% and 92.7%, p = 0.234, for ≥140 / 90 and ≥130 / 80mmHg, respectively). Further analysis using κ-statistics showed acceptable agreement between the two definitions (κ = 0.765, p <0.001). Overall, 26% of patients had oBP ≥140/90 and 52% ≥130 / 80 mmHg (p <0.001), while as expected, the control was significantly higher when the definition of the ESC-ESH was used.
Conclusions: The prevalence of hypertension in renal transplant recipients assessed by 24-hr ABPM is particularly high. Office BP measurements are of poor prognostic value for the diagnosis of hypertension according to ABPM. In addition, ABPM reveals a particularly high prevalence of masked hypertension, a finding of particular concern as the last is associated with increased cardiovascular risk. The above findings support the use of ABPM for proper diagnosis and treatment of hypertension in this population.