NDT Advance Access published online on December 1, 2006
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfl642
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Reverse white-coat effect as an independent risk for microalbuminuria in treated hypertensive patients
Division of Hypertension and Nephrology, Department of Medicine, National Cardiovascular Center, Suita, Japan
Correspondence and offprint requests to: Takeshi Horio, MD, Division of Hypertension and Nephrology, Department of Medicine, National Cardiovascular Center, 5-7-1, Fujishirodai, Suita, Osaka 565-8565, Japan. Email: thorio{at}ri.ncvc.go.jp
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Abstract |
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Background. The influence of the converse phenomenon of white-coat hypertension called ‘reverse white-coat hypertension’ or ‘masked hypertension’ on hypertensive target organ damage has not been fully elucidated. The present study assessed the hypothesis that this phenomenon may specifically associate with microalbuminuria, a marker of early renal damage, in treated hypertension.
Methods. A total of 267 treated essential hypertensive patients (133 men and 134 women; mean age, 66 years) without renal insufficiency or macroalbuminuria were enroled in this study. Patients were classified into three groups by the difference between office and day-time ambulatory systolic blood pressure (BP) levels; i.e. subjects with white-coat effect (W group: office – day-time systolic BP 
20 mmHg, n = 48), with reverse white-coat effect (R group: office – day-time systolic BP < – 10 mmHg, n = 43) and without white-coat or reverse white-coat effect (N group: –10 mmHg 
office – day-time systolic BP <20 mmHg, n = 176). The urinary albumin (U-Alb) level was measured as the albumin to creatinine excretion ratio in the urine. Microalbuminuria was defined as U-Alb of 30 and <300 mg/g Cr.
Results. R group had a well-controlled office BP (130/77 mmHg), but their day-time BP (148/87 mmHg) was elevated compared with the other two groups. The levels of U-Alb excretion in N group, W group and R group were 12.3 (8.4, 25.6), 16.0 (10.5, 31.7) and 24.3 (10.2, 79.7) mg/g Cr [median (interquartile range)], respectively. Both U-Alb level and prevalence of microalbuminuria were significantly greater in R group than in N group. Multivariate analyses revealed that the presence of reverse white-coat effect, but not white-coat effect, was a significant predictor for microalbuminuria, independent of various clinical variables including ambulatory BP levels (odds ratio 2.63 vs N group, P = 0.02).
Conclusion. These findings suggest that the presence of reverse white-coat effect may be an independent risk for early renal damage in treated hypertensive patients.
Keywords: ambulatory blood pressure monitoring; hypertension; microalbuminuria