Association between white-coat effect and blunted dipping of nocturnal blood pressure.
BACKGROUND
In this study, we assessed whether the white-coat effect (difference between office and daytime blood pressure (BP)) is associated with nondipping (absence of BP decrease at night).


METHODS
Data were available in 371 individuals of African descent from 74 families selected from a population-based hypertension register in the Seychelles Islands and in 295 Caucasian individuals randomly selected from a population-based study in Switzerland. We used standard multiple linear regression in the Swiss data and generalized estimating equations to account for familial correlations in the Seychelles data.


RESULTS
The prevalence of systolic and diastolic nondipping (<10% nocturnal BP decrease) and white-coat hypertension (WCH) was respectively 51, 46, and 4% in blacks and 33, 37, and 7% in whites. When white coat effect and nocturnal dipping were taken as continuous variables (mm Hg), systolic (SBP) and diastolic BP (DBP) dipping were associated inversely and independently with white-coat effect (P < 0.05) in both populations. Analogously, the difference between office and daytime heart rate was inversely associated with the difference between daytime and night-time heart rate in the two populations. These results did not change after adjustment for potential confounders.


CONCLUSIONS
The white-coat effect is associated with BP nondipping. The similar associations between office-daytime values and daytime-night-time values for both BP and heart rate suggest that the sympathetic nervous system might play a role. Our findings also further stress the interest, for clinicians, of assessing the presence of a white-coat effect as a means to further identify patients at increased cardiovascular risk and guide treatment accordingly.
Bochud
Murielle
M
Institut Universitaire de Médecine Sociale et Préventive, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Bovet
Pascal
P
Vollenweider
Peter
P
Maillard
Marc
M
Paccaud
Fred
F
Wandeler
Gilles
G
Gabriel
Anne
A
Burnier
Michel
M
D000328:Adult; D001007:Anxiety / Q000208:ethnology; D001794:Blood Pressure; D001795:Blood Pressure Determination; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D006973:Hypertension / Q000208:ethnology / Q000503:physiopathology* / Q000523:psychology; D008297:Male; D008875:Middle Aged; D010507:Periodicity; D011188:Potassium / Q000652:urine; D012750:Seychelles / Q000208:ethnology; D012964:Sodium / Q000652:urine; D013557:Switzerland / Q000208:ethnology; D044465:White People / Q000208:ethnology
D012964:Sodium; D003404:Creatinine; D011188:Potassium