The perils of determining cardiovascular risk in relation to home blood pressure
In most guidelines, home blood pressure (BP) measurement is recommended for diagnosing hypertension when 24-h ambulatory BP monitoring (ABPM) is not available or not feasible. This recommendation is based upon evidence derived from a number of clinical outcome studies involving study participants followed over a period of years after being assessed for both office and home BP. The superiority of ABPM over home BP in the guidelines for diagnosing hypertension is based upon several factors, including the number of clinical outcome studies, the sample sizes enrolled, the number of out-of-office BP measurements and the extent to which ABPM readings are superior to office BP in predicting future cardiovascular events. In most instances ABPM comes out ahead, although more clinical outcome studies directly comparing ABPM and home BP are needed to resolve the question of which method is superior. The recent development of home BP devices which are capable of recording BP during sleep  may eliminate the differences between these two approaches to obtaining out-of-office BP readings. Furthermore, the use of automated office BP measurements  which are devoid of a white-coat effect (office BP higher than ambulatory/home BP) may reduce the superiority of ABPM and home BP over conventional office BP readings.