Evaluation of Self-Monitoring of Blood Pressure According to the Perhit Study and the Impact on Glomerular Function

Objective: The relationship between hypertension and chronic kidney disease (CKD) is bidirectional. Although intensive blood pressure (BP) control has not been shown to slow the progression of CKD, intensive BP control has been shown to reduce the risk for adverse cardiovascular outcomes in the CKD population. The aim of this study was to help us understand the interplay between self-monitored BP and progress of kidney disease. Design and method: This study is a post-hoc analysis of data from our previous randomised controlled study, PERson-centredness in Hypertension management using Information Technology (PERHIT). We included 949 hypertensive participants who underwent visits at baseline, eight weeks and 12 months. Blood samples were taken at every visit. Half of the participants received a BP monitor and installed a mobile phone program. During eight weeks they daily measured and reported their BP values. Systolic BP (SBP) and diastolic BP (DBP) were used to calculate pulse pressure (PP) and mean arterial pressure (MAP) The association between estimated glomerular filtration rate (eGFR) and BP components were analysed in mixed linear regression models. Results: BP for the intervention and the control group were similar at baseline. Within the intervention group BP and SBP decreased from baseline to eight weeks and 12 months (P<0.001). Also, PP and MAP decreased from baseline to eight weeks (P=0.021 and P=0.004) and 12 months (P=0.035 and P=0.008). Within the control group, a decrease was observed from baseline to 12 months for SBP, DBP and PP (P=0.025, P=0.023 and P=0.036). In the intervention group we observed an association between a decrease in SBP, DBP, PP and MAP and a decline in eGFR (P<0.001, P<0.001, P=0.013 and P<0.001), (table). In the control group similar results was observed only for PP (P=0.027). eGFR decreased significantly (P<0.001) within the intervention group, but not within the control group (P=0.051). Conclusions: In this randomised study we observed an association between a decrease in all BP component and an eGFR decline. Improved BP reduction in the intervention group was associated with a greater reduction in eGFR within the normal range.