High versus low measurement frequency during 24-h ambulatory blood pressure monitoring - a randomized crossover study

Ambulatory blood pressure monitoring (ABPM) may be stressful and associated with discomfort, possibly influenced by the numberof cuff inflations. We compared a low frequency (LF-ABPM) regimen with one cuff inflation per hour, with a high frequency (HF-ABPM) regimen performed according to current guidelines using three cuff-inflations per hour during daytime and two cuff-inflations during night time. In a crossover study, patients underwent ABPMs with both frequencies, in a randomized order, withinan interval of a few days. Patients reported pain (visual analogue scale from 0 to 10) and sleep disturbances after each ABPM. Theprimary endpoint was the difference in mean 24 h systolic BP (SBP) between HF-ABPM and LF-ABPM. A total of 171 patients wererandomized, and data from 131 (age 58 +/- 14 years, 47% females, 24% normotensive, 53% mildly hypertensive, and 22%moderately-severely hypertensive) completing both ABPMs were included in the analysis. Mean SBP was 137.5 mmHg (95% CI,134.8;140.2) for HF-ABPM and 138.2 mmHg (95%CI, 135.2;141.1) for LF-ABPM. The 95% limits of agreement were-15.3 mmHg and+14.0 mmHg. Mean 24 h SBP difference between HF-ABPM and LF-ABPM was-0.7 mmHg (95%CI,-2.0;0.6). Coefficients ofvariation were similar for LF-ABPM and HF-ABPM. Pain scores (median with interquartile range), for HF-ABPM and LF-ABPM were 1.5(0.6;3.0) and 1.3 (0.6;2.9) during daytime, and 1.3 (0.4:3.4) and 0.9 (0.4;2.0) during nighttime (P< 0.05 for both differences). Weconclude that LF-ABPM and HF-ABPM values are in good agreement without any clinically relevant differences in BP. Furthermore,LF-ABPM causes a relatively modest reduction in procedure-related pain