title: The 'ABPM effect' gradually decreases but does not disappear in successive sessions of ambulatory monitoring.
abstract: 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.
authors.affiliation: Hypertension and Vascular Risk Unit, Hospital Clínico Universitario, Santiago de Compostela, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Calvo
authors.forename: Ramón C
authors.initials: RC
authors.lastname: Hermida
authors.forename: Diana E
authors.initials: DE
authors.lastname: Ayala
authors.forename: José E
authors.initials: JE
authors.lastname: López
authors.forename: José R
authors.initials: JR
authors.lastname: Fernández
authors.forename: María J
authors.initials: MJ
authors.lastname: Domínguez
authors.forename: Artemio
authors.initials: A
authors.lastname: Mojón
authors.forename: Manuel
authors.initials: M
authors.lastname: Covelo
mesh_terms: 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
chemical_list: D000959:Antihypertensive Agents