Advice from the BP Measurement Experts
A recent article in the Journal of Clinical Hypertension does a colorful yet effective job of describing the transient effects of White Coat Hypertension (WCH) when meeting a new physician. Studies show that patients who are not hypertensive but show high BP readings when visiting a new doctor for their first time can continue to present with these elevated BP readings for three to six visits. Although treatment for hypertension based on these measurements is not recommended, the gold standard diagnostic test for WCH, a 24-hour study with an ambulatory blood pressure (ABP) monitor, can more effectively determine whether treatment is, in fact, needed.
A single measurement is very limited in its diagnostic value.
In the short but informative summary on WCH, Drs. Cohen and Townsend highlight one of the 10 Factors That Can Affect Blood Pressure Readings, emotional state, in this case anxiety. This article places some interesting context to its effects on your BP. While it may be constantly changing throughout the day, there are some predictable patterns to the behavior of your BP, such as an increase due to nervousness. Additionally, your body can change its behavior or overcome some of these patterns. For example, patients showed a decrease in BP over a period of three to six visits. While you may expect your BP to be a certain level given how your body has reacted in the past (i.e. that you usually present to your physician with high BPs), your body can sometimes cope with these external factors which may result in different results (i.e. that your BP is lower than you expect it to be). With all these interactions, the most important thing to note about your BP is the overall trend over a day, month, or year. A single measurement is very limited in its diagnostic value. However, trends identified by multiple measurements over a 24-hour period as uncovered by an ABP monitor or over longer periods of time with a home BP monitor, where appropriate, may provide valuable insight into whether attention is needed.
In fact, this is exactly where Drs. Cohen and Townsend end up in their review of studies. While they present strong support for patients developing hypertension given WCH, there is significantly less evidence to show that WCH leads to a higher risk of cardiovascular events and should be treated. Because treatment for hypertension may not be recommended for patients with WCH, awareness of your lifestyle and its impact on your cardiovascular health through frequent monitoring of your BP become very important.