Factors associated with uncontrolled hypertension among renal transplant recipients attending nephrology clinics in Nairobi

Abstract

Background Renal transplantation remains the therapeutic modality of choice for patients with end stage renal disease. Prevalence of hypertension remains high post transplantation, with alarmingly low proportion of patients achieving target blood pressure levels. Pathophysiology of post renal transplant hypertension is multifactorial, with recipient, donor and immunotherapeutic factors implicated. Uncontrolled hypertension results in reduced graft and patient survival. Determining the factors associated with uncontrolled hypertension among renal transplant recipients is thus of utmost importance for improved blood pressure control, which has been shown to positively impact graft and patient survival. Objective of the Study The aim of the study was to determine the factors associated with hypertension among renal transplant recipients, their levels of adherence to antihypertensive medications, and to document the changes in antihypertensive medication use post transplantation. Study design Cross-sectional descriptive study. Participants and Study Site Renal transplant recipients on follow up at the Renal Unit Transplant Clinic at Kenyatta National Hospital (KNH) and nephrology clinics at Kenyatta National Hospital Doctor’s Plaza, Nairobi. Methods Consecutive kidney transplant recipients were screened for eligibility and enrolled into the study during the months of November 2012 to February 2013. Clinical and sociodemographic data were recorded in a pre-designed questionnaire. Participants also filled in the self-administered 8-item Morisky Medication Adherence Scale. Subsequently samples for determination of serum creatinine and spot urine albumin:creatinine ratio were collected.Data Analysis Variables were calculated as proportions with 95% confidence intervals. Continuous data was summarized using means, mode and medians while categorical data was analyzed using proportions. Correlations were tested using the chi-square test for categorical variables, while student’s t test was used for comparisons between continuous variables. Statistical significance was defined at a P value of less than 0.05. Results Between November 2012 and February 2013 a total of 85 renal transplant recipients were studied. There was a male predominance with a male to female ratio of 1.9:1. The mean age was 42.4(±12.2) years. The proportion of patients with uncontrolled hypertension in the post transplant period was 68.2% (95% CI 57.6% - 77.6%). Only a third of all the patients were fully adherent to antihypertensive medications. The mean Morisky adherence score was 6.8. There was a significant reduction in mean number of antihypertensives used from 3.3 (±1.6) drugs per patient in the pre-transplant period to 2.1 (±0.9) drugs per patient in the post transplant period (p <0.001). Mean systolic and diastolic pressures were also significantly lower in the post transplant period (SBP 144.5 mmHg versus 131.8 mmHg; DBP 103.6 mmHg versus 83.5 mmHg in the pre-and post-transplant periods respectively (p <0.001). The most commonly used antihypertensive agents were calcium channel blockers and beta blockers. Male sex and non-adherence were independently associated with uncontrolled hypertension. Conclusion Uncontrolled hypertension remains highly prevalent in the post-transplant period. There is a reduction in the mean number of antihypertensive medications used post transplantation. Nonadherence to antihypertensive medications and male sex were predictors of uncontrolled hypertension. Recommendations Intensification of blood pressure control among renal transplant recipients, as well as strategies to improve patient adherence to antihypertensive medication should be done. Further studies are