High Incidence of Masked Hypertension in Patients with Obstructive Sleep Apnoea Despite Normal Automated Office Blood Pressure Measurement Results

Introduction: Obstructive sleep apnoea (OSA) is a well-known risk factor for masked hypertension (MH) and masked uncontrolled hypertension (MUCH). Automated ambulatory office blood pressure measurement (AOBP) might better correlate with the results of ambulatory blood pressure measurements (ABPM) compared to routine office blood pressure measurement (OBPM). The aim of this study was to compare the diagnostic rate of MH/MUCH when using OBPM and AOBP in combination with ABPM. Material and methods: 65 OSA patients, of which 58 were males, (AHI > 5, mean 44.4; range 5–103) of average age 48.8 ± 10.7 years were involved in this study. Following MH/MUCH criteria were used; Criteria I: OBPM < 140/90 mm Hg and daytime ABPM > 135/85 mm Hg; Criteria II: AOBP < 140/90 mm Hg and daytime ABPM > 135/85 mm Hg; Criteria III: AOBP < 135/85 mm Hg and daytime ABPM > 135/85 mm Hg. Results: MH/MUCH criteria I was met in 16 patients (24.6%) with criteria II being met in 37 patients (56.9%), and criteria III in 33 (51.0%), p < 0.0001. Both systolic and diastolic OBPM were significantly higher than AOBP; Systolic (mm Hg): 135.3 ± 12.3 vs. 122.1 ± 10.1 (p < 0.0001); Diastolic (mm Hg): 87.4 ± 8.9 vs. 77.1 ± 9.3 (p < 0.0001). AOBP was significantly lower than daytime ABPM; Systolic (mm Hg): 122.1 ± 10.1 vs. 138.9 ± 10.5 (p < 0.0001); Diastolic (mm Hg): 77.1 ± 9.3 vs. 81.6 ± 8.1 (p < 0.0001). Non-dipping phenomenon was present in 38 patients (58.4%). Nocturnal hypertension was present in 55 patients (84.6%). Conclusions: In patients with OSA there is a much higher prevalence of MH/MUCH despite normal AOBP, therefore it is necessary to perform a 24-hour ABPM even if OBPM and AOBP are normal.