Masked hypertension: how can the condition be detected?

Recent evidence demonstrates that masked hypertension is a significant predictor of cardiovascular disease, but the problem for clinical practice is how to identify these patients. Furthermore, the prevalence of masked hypertension in the general population or in subjects with transient blood pressure elevation is still unknown. Data obtained in several cross-sectional studies have demonstrated large differences in the prevalence of masked hypertension, with prevalence rates from a low of 8% to a high of 49%. Two population-based studies performed in Italy and in Japan report prevalence of 9% and of 13.4%, respectively. A 49% frequency of masked hypertension has been found among subjects with transiently elevated clinic blood pressure. Several factors can selectively raise ambulatory blood pressure including age, sex, smoking, alcohol use, contraceptive use in women, and sedentary habits. Reactivity to daily life stressors and behavioural factors are other important determinants of ambulatory blood pressure. On the basis of the available evidence, masked hypertension should be searched for in individuals who are more likely to have this condition or are at increased risk of cardiovascular complications including diabetic individuals and subjects with kidney disease. Further research is needed to determine whether the use of ambulatory blood pressure monitoring is cost-effective in these subjects.