White coat hypertension
White coat hypertension (abbreviated alternatively as WCH or WCHT), not to be confused with the white coat effect (WCE), is commonly defined as typical in-clinic blood pressure (BP) measurements of 140/90 mm Hg or more in the presence of multiple daytime out-of-clinic home or ambulatory BP readings averaging less than 135/85 mm Hg in untreated individuals 1-4.
Alternatively, mean 24-hour BP readings of less than 130/80 mm Hg have been proposed as the out-of-clinic cutoff value 1,2.
Discrepancies and similarities from author to author between the definitions of the WCE and WCH (and its synonyms) should be taken into account when examining this topic and each individual paper.
Colloquially, WCH may be referred to as white coat syndrome. More recently, the terms isolated office hypertension or isolated clinic hypertension have been proposed as replacements for WCH as they more accurately represent the recent body of evidence with respect to the etiology and pathophysiology behind the currently popular term of WCH.
Most patients experience elevated BP readings in-clinic vs. out-of-clinic and most of these are hypertensive in and out of office to begin with. However, a smaller subset of patients have normal BP readings out-of-office in conjunction with hypertensive measurements in a medical environment 1.
Even so, most individuals with WCH have higher out-of-office BP readings than truly normotensive individuals 2.
Overall, the prevalence of WCH appears to be approximately 9%-15.4% among patients with in-office hypertension but these values depend on the cut-off values used in each study and the study’s population 5,9.
WCH is most likely to occur in women as well as elderly patients 5,6.
The etiology and pathophysiology behind WCH is not fully understood.
Traditionally, it has been believed that the sight of or interaction with a physician or the actual physical measurement of blood pressure (cuff inflation) brings about WCH as a result of an alarm reaction.
And so, as with other forms of hypertension, sympathetic overdrive occurs in cases of WCH 2.
But in at least one study it has been shown that the alerting reaction and pressor response to the physician’s visit does not accurately reflect the difference between in-clinic and daytime average blood pressure values. Therefore, using such a difference as a measurement of the WCE is potentially erroneous 10.
Hence, the true reason behind WCH is not clear and still under investigation, while studies on the traditional explanations for WCH have largely negated their validity 10,11.
It is currently presumed that a multitude of behavioral and other modulating factors (yet to be fully elucidated) affect daytime and clinic BP and account for the actual clinic-daytime BP difference. 1,2,10.
Treament and prognosis
Between 10-30% of subjects with WCH develop sustained hypertension within 3-5 years and the percentage rises to 42.6% when reassessed 10 years later 7,8.
In the long term, WCH may lead to an increased risk for stroke, cardiovascular events, and the development of diabetes mellitus 1,2,9.
- 1. Kaplan NM, Victor RG. Kaplan's Clinical Hypertension. LWW. ISBN:1451190131. Read it at Google Books - Find it at Amazon
- 2. Manual of Hypertension of the European Society of Hypertension, Second Edition. CRC Press. ISBN:1841849979. Read it at Google Books - Find it at Amazon
- 3. Ram CVS. Hypertension: A Clinical Guide. CRC Press. ISBN:1840762012. Read it at Google Books - Find it at Amazon
- 4. Celis H, Fagard RH. White-coat hypertension: a clinical review. Eur. J. Intern. Med. 2004;15 (6): 348-357. doi:10.1016/j.ejim.2004.08.001 - Pubmed citation
- 5. Dolan E, Stanton A, Atkins N et-al. Determinants of white-coat hypertension. Blood Press Monit. 2005;9 (6): 307-9. Pubmed citation
- 6. Jumabay M, Ozawa Y, Kawamura H et-al. White coat hypertension in centenarians. Am. J. Hypertens. 2005;18 (8): 1040-5. doi:10.1016/j.amjhyper.2005.03.732 - Pubmed citation
- 7. Pickering TG, Coats A, Mallion JM et-al. Blood Pressure Monitoring. Task force V: White-coat hypertension. Blood Press Monit. 2000;4 (6): 333-41. Pubmed citation
- 8. Mancia G, Bombelli M, Facchetti R et-al. Long-term risk of sustained hypertension in white-coat or masked hypertension. Hypertension. 2009;54 (2): 226-32. doi:10.1161/HYPERTENSIONAHA.109.129882 - Pubmed citation
- 9. Verdecchia P, Reboldi GP, Angeli F et-al. Short- and long-term incidence of stroke in white-coat hypertension. Hypertension. 2005;45 (2): 203-8. doi:10.1161/01.HYP.0000151623.49780.89 - Pubmed citation
- 10. Parati G, Ulian L, Santucciu C et-al. Difference between clinic and daytime blood pressure is not a measure of the white coat effect. Hypertension. 1998;31 (5): 1185-9. doi:10.1161/01.HYP.31.5.1185 - Pubmed citation
- 11. Parati G, Pomidossi G, Casadei R et-al. Lack of alerting reactions to intermittent cuff inflations during noninvasive blood pressure monitoring. Hypertension. 1985;7 (4): 597-601. Pubmed citation