Graded Association Between Kidney Function and Impaired Orthostatic Blood Pressure Stabilization in Older Adults

Mark Canney, Matthew D. L. O'Connell, Donal J. Sexton, Neil O'Leary, Rose Anne Kenny, Mark A. Little, Conall M. O'Seaghdha

Impaired orthostatic blood pressure (BP) stabilization is highly prevalent in older adults and is a predictor of end-organ injury, falls, and mortality. We sought to characterize the relationship between postural BP responses and the kidney. We performed a cross-sectional analysis of 4204 participants from The Irish Longitudinal Study on Ageing, a national cohort of community-dwelling adults aged ≥50 years. Beat-to-beat systolic and diastolic BP were measured during a 2-minute active stand test. The primary predictor was cystatin C estimated glomerular filtration rate (eGFR) categorized as follows (mL/min per 1.73 m(2)): ≥90 (reference, n=1414); 75 to 89 (n=1379); 60 to 74 (n=942); 45 to 59 (n=337); <45 (n=132). We examined the association between eGFR categories and (1) sustained orthostatic hypotension, defined as a BP drop exceeding consensus thresholds (systolic BP drop ≥20 mm Hg±diastolic BP drop ≥10 mm Hg) at each 10-second interval from 60 to 110 seconds inclusive; (2) pattern of BP stabilization, characterized as the difference from baseline in mean systolic BP/diastolic BP at 10-second intervals. The mean age of subjects was 61.6 years; 47% of subjects were male, and the median eGFR was 82 mL/min per 1.73 m(2). After multivariable adjustment, participants with eGFR <60 mL/min per 1.73 m(2) were approximately twice as likely to have sustained orthostatic hypotension (P=0.008 for trend across eGFR categories). We observed a graded association between eGFR categories and impaired orthostatic BP stabilization, particularly within the first minute of standing. We report a novel, graded relationship between diminished eGFR and impaired orthostatic BP stabilization. Mapping the postural BP response merits further study in kidney disease as a potential means of identifying those at risk of hypotension-related events.