Automated, ambulatory, or conventional blood pressure measurement in pregnancy: Which is the better predictor of severe hypertension?

OBJECTIVES: Our purpose was to investigate the benefit, ii any, of automated blood pressure monitoring over obstetric day unit conventional blood pressure measurement in the assessment of hypertensive pregnancies. STUDY DESIGN: A prospective, observational study was carried out in two large teaching hospitals. Three hundred and forty-eight women with a confirmed clinic blood pressure of at least 140/90 mm Hg were recruited. Conventional blood pressure measurements (less than or equal to 5) were obtained on the day unit and simultaneously an ambulatory blood pressure monitor was applied for 24 hours. The predictive ability of day unit assessment (blood pressure >140/90 mm Hg) and automated blood pressure monitoring (blood pressure >130/85 mm Hg) was compared. Principal outcome measures included the occurrence of severe hypertension (>160/110 mm Hg) and proteinuria (>500 mg or 2+) within (a) 2 weeks and (b) the remainder of the pregnancy. Thompson's method was used to compare sensitivity and specificity of the day unit blood pressure and automated blood pressure monitoring. RESULTS: Three hundred and forty-eight women were recruited to the study. The comparison between automated blood pressure monitoring and conventional blood pressure measurement for both sensitivity and specificity for systolic and diastolic blood pressure revealed increased sensitivity and decreased specificity with automated blood pressure monitoring for all principal outcomes except development of proteinuria for systolic blood pressure. Sensitivity for the outcomes was increased with automated blood pressure monitoring by between 14% and 27% for systolic blood pressure and between 7% and 39% for diastolic blood pressure, with the greatest improvement seen for the development of severe hypertension within 2 weeks of assessment. CONCLUSIONS: In the assessment of hypertensive pregnancies, automated blood pressure measurement was a significantly better predictor (compared with conventional day unit assessment) for the development of severe hypertension within 2 weeks of assessment for both systolic and diastolic blood pressure.