Prognostic Value of Home Blood Pressure Monitoring
Although it has been well established that elevated clinic-derived measures of blood pressure were associated with both target organ complications (like left ventricular hypertrophy) and increased risk for cardiovascular disease, the predictive relation between home blood pressures and target organ damage and risk for cardiovascular disease was unknown.
However, because the physiological damage caused by elevated arterial pressures occurs continuously but gradually throughout daily life and not just during visits to the clinic, it was hypothesized that home measures would predict target organ pathology and associated risk for cardiovascular disease better than clinic-derived indices of blood pressure.
Although not many studies have explored the relation between home monitoring and evidence of target organ damage or subsequent risk for cardiovascular disease, of those that exist, measures of left ventricular hypertrophy were shown to be more strongly correlated with self-determined blood pressures than clinic-derived blood pressures (White et al., 1999).
To provide further support for the prognostic utility of home monitoring, White et al. cited two recent prospective trials in which self-determined blood pressures were more strongly correlated with risk for cardiovascular diseases than clinic-derived blood pressure measures (Imai et al., 1996; Ohkubo et al., 1998b).
In summary, although home blood pressure monitoring serves as a helpful tool for following patients with essential hypertension as well as monitoring treatment effectiveness, it is less accurate in making the initial diagnosis of essential hypertension (Herpin et al., 2000). Additionally, if accurate home-derived measures of blood pressure can be obtained, they can differentiate patients with sustained elevated pressures from patients who exhibit elevated blood pressures only in the clinic (isolated clinic hypertensives or ‘white coat’ hypertensives), who presumably may be at lesser risk for target organ complications associated with hypertension.
In this regard, home measures of blood pressure can be a useful proxy when ambulatory monitoring equipment is not available to confirm presence of isolated clinic hypertension (isolated clinic hypertension will be discussed in greater detail later in this section).
There are several limitations to home measurement of blood pressure, as well, including the limited amount of prospective data linking various levels of home-determined blood pressures to associated risk for cardiovascular disease and limited information pertaining to the optimal schedule for self-monitoring of blood pressure (White et al., 1999).