Hypertension Canada continues to emphasize the use of out-of-office measurements to rule out white coat hyper-tension in subjects with increased BP in the office . Its prevalence is estimated to be between 9% and 30%.It is more common in women, older subjects, nonsmokers, subjects with mildly elevated office BP, pregnant women, and subjects without target organ damage. Subjects with white coat hypertension have been shown to have an overall cardiovascular risk that approximates that of normotensive subjects. Thus, at present, there is no evidence to support pharmacologic treatment of subjects with white coat hypertension. Because treated and untreated subjects have long-term cardiovascular risk similar to that of treated and untreated normotensive individuals, respec-tively,it is clinically relevant to identify individuals with white coat hypertension to avoid overtreatment. In individuals with diabetes, diagnosis of hypertension is probable when OBPM is 130/80 for 3 or more mea-surements on different days; out-of-office measurements could be considered to rule out white coat hypertension, when suspected. Although the diagnostic thresholds for ABPM and HBPM (as well as for AOBP) have not yet been established in subjects with diabetes, they are probably 601 lower than those mentioned for diagnosis of hypertension in the general population.
In cases of normal BP in the office, the possibility of masked hypertension (high out-of-office BP) should be sus-pected in the following cases: older age, men, current smoking, heavy alcohol drinking, obesity, diabetes mellitus, or other traditional cardiovascular risk factors, as well as in cases of electrocardiographic left ventricular hypertrophy, and high-normal systolic and diastolic office BP.Masked hypertension is common in untreated adults, with a possible prevalence of approximately 20%, which is even higher in individuals with controlled office BP (more than 1 of 3 treated individuals).48 When suspected, masked hyperten-sion should be ruled out by performing out-of-office mea-surements. In subjects with diabetes, absence of nocturnal dipping in BP (identified using ABPM) is common and correlates with higher cardiovascular mortality. Specif-ically, although mean attended AOBP and daytime ABPM have been shown to be similar in subjects with diabetes, baseline 24-hour SBP (hazard ratio, 1.53; 95% CI, 1.28-2.03) and nighttime SBP (hazard ratio, 1.50; 95% CI, 1.26-1.89) were independent predictors of short-term cardiovas-cular outcomes. Furthermore, in diabetes the adjusted odds ratio for progression to macroalbuminuria has been shown to be more than eight-fold higher in the masked hypertension group (diagnosed with HBPM) than in the controlled BP group.