Incidence and Factors Associated with Uncontrolled Hypertension at 12 months after Kidney Transplantation in Saudi Arabia

INTRODUCTION: Uncontrolled blood pressure (uBP) after kidney transplantation (KTx) is very common and is associated with significant morbidity. However, studies that assess its incidence and risk factors are limited and outdated in the Middle East. METHODS: This is a single-center retrospective study of KTx recipients (KTRs) in our center between January 2017 and May 2020 with a 12-month follow-up period. The target of hypertension treatment during the time of this study was <140/90 mm Hg, according to the published guidelines. We divided patients according to their blood pressure (BP) control at 1 year into two groups: controlled BP (cBP) (<140/90) and uBP (≥140/90). We studied the association between uBP and patients' demographics, baseline cardiovascular risk factors, and changes in their metabolic and cardiovascular profile during the first 12 months post-KTx. RESULTS: A total of 254 KTRs were included. 79.2% developed post-KTx hypertension, 74% were ≥30 years, 58% were men, and 80% were living donor KTRs. The renal replacement modality among our patients pre-KTx was hemodialysis in 78.4%, peritoneal dialysis in 11.5%, and 10.1% underwent preemptive transplantation. At 1 year, 76 (29.9%) KTRs did not attain the target BP goal. Systolic BP (SBP) decreased from baseline to 12 months by 13 ± 24 mm Hg in the cBP group and increased by 8.7 ± 21 mm Hg in the uBP group (p < 0.001). Additionally, diastolic BP (DBP) decreased by 8.5 ± 16.9 mm Hg in the cBP group and increased by 2.3 ± 18.8 mm Hg in the uBP group (p < 0.001). Factors associated with uBP included age (47 vs. 41 years, p = 0.008) and diabetes mellitus (p = 0.012). Contrarily, gender, dialysis vintage, preemptive transplantation, type of dialysis (hemodialysis vs. peritoneal dialysis), type of transplant (living donor KTx vs. deceased donor KTx), and smoking were not different among the two groups. There were no significant differences between the two groups in regard to changes in creatinine, weight, A1c, low-density lipoprotein, and parathyroid hormone levels. Additionally, rate of rejection, new onset diabetes post-transplant, and persistent hyperthyroidism were not different between the groups. However, higher body mass index at 12 months was associated with a higher incidence of uBP (27.2 ± 5.9 vs. 29.2 ± 5.4, p = 0.013). Using multivariate analysis, we found that serum creatinine at 12 months was the only predictor of uBP (OR = 1.005 [1-1.011], p = 0.036). CONCLUSION: At 1-year post-renal transplantation, about one-third of KTRs had uBP despite multiple antihypertensive medications. SBP and DBP significantly trended upward after transplantation in uBP patients, whereas SBP and DBP significantly trended downward after transplantation in cBP patients. Serum creatinine at 12 months was the only factor independently associated with uBP.