Unmasking masked hypertension: prevalence, clinical implications, diagnosis, correlates and future directions

‘Masked hypertension’ is defined as having non-elevated clinic blood pressure (BP) with elevated out-of-clinic average BP, typically determined by ambulatory BP monitoring. Approximately 15–30% of adults with non-elevated clinic BP have masked hypertension. Masked hypertension is associated with increased risks of cardiovascular morbidity and mortality compared with sustained normotension (non-elevated clinic and ambulatory BP), which is similar to or approaching the risk associated with sustained hypertension (elevated clinic and ambulatory BP). The confluence of increased cardiovascular risk and a failure to be diagnosed by the conventional approach of clinic BP measurement makes masked hypertension a significant public health concern. However, many important questions remain. First, the definition of masked hypertension varies across studies. Further, the best approach in the clinical setting to exclude masked hypertension also remains unknown. It is unclear whether home BP monitoring is an adequate substitute for ambulatory BP monitoring in identifying masked hypertension. Few studies have examined the mechanistic pathways that may explain masked hypertension. Finally, scarce data are available on the best approach to treating individuals with masked hypertension. Herein, we review the current literature on masked hypertension including definition, prevalence, clinical implications, special patient populations, correlates, issues related to diagnosis, treatment and areas for future research.