Automated Office Blood Pressure is Associated with Urine Albumin Excretion in Hypertensive Subjects

BACKGROUND We aimed to investigate the association between automated office blood pressure (AOBP) readings and urine albumin excretion (UAE), and to assess if this association is as close as that between 24-h ambulatory blood pressure (ABP) and UAE. A strong association would suggest that AOBP may serve as an indicator of early renal impairment. METHODS In a sample of 162 hypertensives, we compared AOBP with ABP measurements and their associations with UAE in two consecutive 24-h urine collections measured by an immunoturbidimetric assay. Microalbuminuria was defined as UAE of 30-300 mg/24 h. RESULTS The age of the subjects was 53 +/- 13 (mean +/- s.d.) years. Twenty-two were microalbuminuric. In those, AOBP and 24-h ABP were higher than in the normoalbuminuric subjects: 152 +/- 19 and 147 +/- 20 vs. 138 +/- 15 and 130 +/- 11 mm Hg for systolic blood pressure (SBP), and 97 +/- 15 and 92 +/- 14 vs. 86 +/- 10 and 82 +/- 8 mm Hg for diastolic blood pressure (DBP) (P < 0.001). Correlations between AOBP and 24-h ABP with log-transformed urine albumin were 0.30 (P < 0.001) and 0.43 (P < 0.001) for SBP and 0.27 (P < 0.001) and 0.33 (P < 0.001) for DBP. Adjusting for age, sex, body mass index, and estimated glomerular filtration rate, both AOBP and 24-h ABP were independently associated with urine albumin (P < 0.001 for both associations). Receiver operating characteristics curve analysis showed a similar predictive ability for microalbuminuria for AOBP and for 24-h ABP (area under the curve: 0.819 (P < 0.001) for SBP, 0.836 (P < 0.001) for DBP vs. 0.830 (P < 0.001) for SBP and 0.845 (P < 0.001) for DBP). CONCLUSIONS In this study, microalbuminuria correlated similarly with high-quality AOBP and ABP readings, further supporting the use of AOBP in the clinical setting.