Hypertensive patients with “reverse white-coat hypertension” are at increased risk for the condition.
High ambulatory but normal or well-controlled office BP, a condition known as “reverse white-coat hypertension,” is an independent risk factor for microalbuminuria in patients with treated hypertension.
Takeshi Horio, MD, and his colleagues at the National Cardiovascular Center in Suita, Japan, studied 267 patients (mean age, 66 years) with essential hypertension. All patients had received antihypertensive drug therapy for at least one year (mean, 12 years).
All patients underwent 24-hour ambulatory BP monitoring. Office BP was determined by averaging six measurements taken on three separate occasions during a three-month period. Three groups of patients were identified based on the pattern and magnitude of the difference between office and daytime ambulatory systolic BP: white-coat effect patients (office BP at least 20 mm Hg higher than ambulatory BP); reverse white-coat effect patients (office BP up to 10 mm Hg lower than ambulatory BP); and patients without white-coat or reverse white-coat effect (N group). Microalbuminuria was defined as a urinary albumin level of 30 mg/g or higher and urinary creatinine below 300 mg/g.
Of the 267 patients, 48 (18%) had the white-coat effect, 43 (16%) had the reverse white-coat effect, and 176 (66%) were in the N group. All three groups were similar in terms of the prevalence of diabetes and hyperlipidemia, the rate of current smokers, renal function, glucose and lipid parameters, and classes of antihypertensive agents used.
Urinary albumin levels and the proportion of patients with microalbuminuria were higher in the reverse white-coat group than in the N group. Urinary albumin levels and the prevalence of microalbuminuria were not higher in the patients with white-coat effect than in the N group.
Compared with the N group, the reverse white-coat group had a significant 2.63 times greater risk of microalbuminuria; the risk was a nonsignificant 16% greater in the group with the white-coat effect. The predictive value of reverse white-coat effect for microalbuminuria was independent of age, sex, hypertension duration, use of renin-angiotensin system inhibitors, diabetes, renal function, and daytime mean systolic and diastolic BP.
“Reverse white-coat effect may be an independent risk for early renal damage in treated hypertensive patients,” the researchers wrote in Nephrology Dialysis Transplantation (2007;22:911-916). “Ambulatory or home BP monitoring seems to be necessary to unmask this latent risk that is not detectable by routine BP measuring in the office.”