POS-260 ASSOCIATION OF BLOOD PRESSURE VARIABILITY AND NON-DIPPING WITH THE PROGRESSION OF CHRONIC KIDNEY DISEASE AND CARDIOVASCULAR OUTCOMES- A SINGLE-CENTRE PROSPECTIVE OBSERVATIONAL STUDY

Abstract

Hypertension is seen in almost seventy percent of patients with chronic kidney disease (CKD). The association of blood pressure variability and non-dipping with the progression of chronic kidney disease (CKD) and cardiovascular events is unclear. We aimed to study if blood pressure variability and non-dipping were associated with the progression of chronic kidney disease and cardiovascular events. This was a single-centre, prospective observational study, conducted at a tertiary care centre in South India over eighteen months. Patients with CKD with estimated glomerular filtration rate (eGFR) between 59 and 15 ml/minute per1.73 m2, and aged between 18 and 70years were included in the study. Standardized clinic blood pressure (BP) and 24-hour ambulatory BP were recorded in all enrolled patients. All study participants had follow-up visits every three months for one year. Office BP and serum creatinine were recorded during the visit and the history of occurrence of cardiovascular events were noted. The association of ambulatory blood pressure monitoring (ABPM) parameters with cardiovascular and renal outcomes was analyzed. The cardiovascular outcome was defined as a composite of nonfatal stroke, nonfatal myocardial infarction, and cardiovascular death. The renal outcome was defined as a composite of end-stage renal disease (eGFR<15ml/minute/1.73m2) or the initiation of renal replacement therapy. The correlation of BP variability and non-dipping with decline in glomerular filtration rate was also analyzed. Of the seventy-six study participants, 49(64.5%) were male and the mean age was 54±12 years. When the index of dipping was analyzed we found that 15(19.7%) were dippers, 40 (52.6%) were non-dippers and 21(27.6%) were reverse dippers. The percentage decline in eGFR over one year was significantly more in non-dippers (35.49 ± 19.29 ml/minute/1.73m2) compared to dippers (23.24 ± 12.19ml/minute/1.73m2) (p = 0.022). The baseline characteristics of dippers and non-dippers given in Table 1. At one year, out of the seventy-six study participants, 29(38.2%) had the defined cardiovascular outcome. Cardiovascular outcome was significantly associated with number of anti-hypertensives used (p=0.035), dipping status(p=0.029), 24-hour systolic BP(p=0.038), night systolic BP(p=0.014), index of BP dipping(p=0.014), and BP variability(p=0.036). On multivariate analysis, non-dipping was independently associated with cardiovascular events. The composite renal outcome was seen in 22(28.9%) patients. The renal outcome was found to be significantly associated with diabetes(p=0.053), 24-hour systolic BP(p=0.000), day systolic BP(p=0.001), night systolic BP(p=0.000), index of BP dipping(p=0.000), and BP variability(p=0.071). On multivariate analysis, non-dipping (p=0.030) was independently associated with significant decline in eGFR. The index of nocturnal dipping (r=-0.522, p<0.001) and blood pressure variability (r=0.324, p=0.004) showed a significant correlation with the decline in glomerular filtration rate over one year. In chronic kidney disease ABPM parameters like non-dipping and short-term blood pressure variability were associated with poor renal and cardiovascular outcomes. Although ABPM is time-consuming our study demonstrated that information from ABPM can potentially impact future CV and renal outcomes in patients with CKD.