Reproducibility of masked hypertension in adults with untreated borderline office blood pressure: comparison of ambulatory and home monitoring.

BACKGROUND: We examined short-term reproducibility of masked hypertension (MH) among adults with recent "borderline" office blood pressure (BP) and compared agreement of ambulatory BP monitoring (ABPM) and home BP monitoring (HBPM) in detecting MH.
METHODS: Fifty participants underwent repeated office BP measurements, 24-h ABPM, and HBPM sessions 1-week apart. Participants with office average <140/90 mm Hg were considered to have MH if daytime ABPM average was ≥135/85 mm Hg; they were considered to have MH by HBPM if the average was ≥135/85 mm Hg. Agreements were quantified using κ. We calculated sensitivity and specificity of daytime ABPM-office average pairing and HBPM session-office average pairing for diagnosing MH using a "standard" of two pairings of office and 24-h average ABPM (using a cutoff ≥130/80 mm Hg).
RESULTS: Prevalence rates of MH based on office-daytime ABPM pairings were 54 and 53%, with agreement of 73% (κ = 0.47; 95% confidence interval (CI) 0.21-0.72). MH was less prevalent (43 and 35%) using HBPM-office pairings, with agreement of 69% (κ = 0.34; 95% CI 0.06-0.62). Office-HBPM pairings and office-daytime ABPM pairings had poor agreement on MH classification on both occasions, with κ of -0.06 and 0.10. Sensitivity and specificity of daytime ABPM-office pairing were 93 and 83%. Sensitivity and specificity of HBPM-office pairing were 23 and 67%.
CONCLUSIONS: MH appears to have fair-to-moderate reproducibility, favoring the hypothesis that office BP measurement systematically fails to identify some patients who should be treated as hypertensive. HBPM may not be adequate for detecting MH, or may identify a different "type" of MH than ABPM.