The 'ABPM effect' gradually decreases but does not disappear in successive sessions of ambulatory monitoring.
OBJECTIVE
Previous results have indicated that ambulatory monitoring provides a pressor effect on patients using the device for the first time, but not on successive sessions of monitoring. Our objective was to validate and quantify the extent and duration of this pressor effect in hypertensive patients repeatedly evaluated every few months.


METHODS
We studied 823 mild-to-moderate hypertensive subjects (347 men), 53.4 +/- 14.1 years of age. Blood pressure was measured at 20-min intervals during the day and at 30-min intervals at night for 48 consecutive hours, and physical activity was simultaneously evaluated every minute with a wrist actigraph. Forty per cent of the patients were evaluated twice or more.


RESULTS
In patients evaluated for the first time, results indicated a highly statistically significant (P < 0.001) reduction during the second day of monitoring as compared to the first in the diurnal mean of systolic and diastolic blood pressure, but not in heart rate or physical activity. This pressor effect remained statistically significant for the first 10 h of monitoring, independent of gender, day of the week of monitoring, or number of antihypertensive drugs used by the patients. The nocturnal mean of blood pressure was, however, similar between both days of sampling. This 'ambulatory monitoring effect' was diminished, although not eliminated, in extent and duration for successive sessions of ambulatory monitoring.


CONCLUSIONS
Ambulatory monitoring for 48 h revealed a statistically significant pressor response that could mostly reflect a novelty effect in the use of the monitoring device. This effect has marked implications in both research and clinical daily practice for a proper diagnosis of hypertension and evaluation of treatment efficacy by the use of ambulatory monitoring.
Calvo
Carlos
C
Hypertension and Vascular Risk Unit, Hospital Clínico Universitario, Santiago de Compostela, Spain.
Hermida
Ramón C
RC
Ayala
Diana E
DE
López
José E
JE
Fernández
José R
JR
Domínguez
María J
MJ
Mojón
Artemio
A
Covelo
Manuel
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D003971:Diastole / Q000187:drug effects / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012146:Rest / Q000502:physiology; D012720:Severity of Illness Index; D012737:Sex Factors; D013599:Systole / Q000187:drug effects / Q000502:physiology; D016896:Treatment Outcome
D000959:Antihypertensive Agents