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.