We aimed to determine the association between office systolic and diastolic blood pressure (SBP and DBP) levels and further decline in renal function among treated hypertensive patients over short and long term periods.Design and Method:
This is a retrospective study of 904 treated hypertensive patients over a 15 year period in a primary care clinic. We calculated the rate of annual decline in renal function using estimated glomerular filtration rate (ΔeGFR). We defined a rate of ΔeGFR ≥ 0 ml/year as renal decline and rate of decline of ΔeGFR <0 ml/year as no decline in renal function, at 5 years, 10 years, and 15years of follow-up. We classified mean BPs into mean SBP < 120, 120–139 and ≥ 140 mmHg and mean DBP to < 80, 81–89 and ≥ 90 mmHg. Ethics approval was obtained. Chi square was used to show the association.Results:
At baseline, mean age of patients was 56.0±9.4 years and 2/3 was female. Mean SBP at 5, 10 and 15 years were 141 ± 11 mmHg, 139 ± 9 mmHg and 138 ± 8 mmHg. Mean DBP at 5, 10 and 15 years were 84 ± 5 mmHg, 83 ± 5 mmHg and 81 ± 4 mmHg respectively. Median annual decline of eGFR at 5, 10 and 15 years were -1.2, -0.6 and −0.9 ml/min per 1.73 m2 per year. There is a positive relationship between mean SBP and deterioration of renal function at 10 years (p = 0.001) and at 15 years (p = 0.007) follow-up. All DBP readings and mean SBP in 5 years did not influence the decline in renal function.Conclusions:
Our study demonstrated that mean SBP in long term but not SBP in short term is an independent determinant for decline in renal function among treated hypertensive patients. This would suggest that any benefit of treating hypertension and slowing the rate of decline of renal function requires long term therapy.