Our study shows that ASqBP showed good correlation with AMBP and OBP when it is used for BP measurement in the Egyptian Hypertension Clinics. There was moderate degree of agreement between ASqBP and ambulatory SBP (24 h and daytime) and fair degree of agreement between ASqBP and ambulatory DBP (24 h and daytime).
Hypertension is very common medical problem affecting 26.3% of adult Egyptians with only 38% of them were aware of having high blood pressure. It was found that only 24% of hypertensive patients were receiving the antihypertensive medications, with control rates (i.e., < 140/90 mmHg) were 8% .
Office BP measurement is the routine in clinical evaluation of patients and follow-up. Because of the white coat effect, several patients have been labeled hypertensive and were prescribed anti-hypertensive medications for life, with subsequent hypotensive episodes. The use of ambulatory BP monitoring has solved to a great extent this problem of labile hypertension, and/or white coat effect. However, it is troublesome as usually disturbed by the effect of inflating cuffs. Therefore, the measurements might not reflect the basal conditions.
Theoretically, ASqBP eliminates the human error as well as attenuates the white coat effect, since it allows for multiple readings to be taken in unattended fashion. The Canadian guidelines recommended the use of automated devices as the method of choice for office BP measurement . In the SPRINT study, BP was measured using an automated BP device (Omron HEM 904), which was preset to wait 5 min before measurements and to take average of three measurements, with a 1-min interval, while sitting in a quiet room unobserved . This emphasizes the clinical importance of using the automated devices for accurate BP measurements in clinical trials.
In the current study, we aimed at comparing sequential blood pressure measurement with both OBP and ambulatory monitoring, to correlate between their readings, and whether automated sequential BP can eliminate the pitfalls of blood pressure measurement as white coat effect.
Our results showed that ASqBP measurement is significantly lower than the OBP measurement. Scherpbier-de Haan et al. revealed in their study, on 83 adult patients, that 30-min ASqBP measurements better reflects the patient’s true BP than standardized OBP does. Their mean 30-min ASqBP readings were 7.6/2.5 mmHg (95% confidence interval [CI] = 6.1 to 9.1/1.5 to 3.4 mmHg) lower than OBP readings .
Leenen et al.  used ASqBP in a community BP survey. ASqBP was seen to have several advantages over manual BP including more accurate and consistent readings without the need for extensive training of research staff. The Ontario Survey on the Prevalence of High Blood Pressure (ON-BP) recorded ASqBP using the BpTRU in 2551 adult subjects, with BP readings also being performed using a standard mercury sphygmomanometer in a sample (n = 238) of this population . ASqBP readings were slightly lower (115/71 mm Hg) than the mean manual BP (118/74 mm Hg). Subsequently, Wilkins et al.  reproduced these findings in a national Canadian health survey, using the BpTRU to assess BP status. Bos and Bui showed a similar result with ASqBP readings which were considerably lower than the readings of the OBP. The mean systolic ASqBP was 22.8 mmHg lower than the mean systolic OBP (95% CI, 19.8–26.1 mmHg). The mean diastolic ASqBP was 11.6 mmHg lower than the mean diastolic OBP (95% CI, 10.2–13.1 mmHg). Considerable differences between OBP and ASqBP existed in patients with and without suspected white-coat hypertension, and differences were larger in individuals aged 70 years or older. These results come in agreement with the findings of the current study, where the ASqBP measurements were lower than OBP.
Beckett and Godwin compared BpTRU automatic blood pressure monitor to mean daytime 24-h ambulatory blood pressure monitoring in the assessment of BP in 481 patients with hypertension. The group mean of the average of five BpTRU readings was not statistically different from the 24-h daytime mean on ABPM with mean ± SD of 140.0 ± 17.71/79.8 ± 10.46 vs 141.5 ± 13.25/79.7 ± 7.79 mmHg, respectively. Within patients, BpTRU average correlated significantly better with daytime ambulatory pressure than did clinic averages (r = 0.571 and r = 0.145, respectively) . These results are different from the values of the current study, where the readings of the ASqBP monitoring were statistically higher than the daytime mean ± SD ABPM measurements’ values which were 137.0 ± 16.8 SBP, vs 135.8 ± 15.7 mmHg, and 86.4 ± 13.8 DBP vs 82.1 ± 13.7 mmHg, (p < 0.001 for both). However, there was good correlation between ASqBP (both systolic and diastolic) and daytime ABPM measurements (r = 0.74, and 0.73, P < 0.0001 respectively).
Godwin et al. studied the manual and automated office measurements in relation to awake ambulatory blood pressure monitoring by taking single automated sequential BP measurement and the mean of three OBP on different sets for 654 hypertensive patients; their results showed that the single ASqBP correlates better than the three mean OBP with the daytime ABPM which is similar to the results of the present study. In this study, Pearson correlations were as following: daytime ABPM vs ASqBP systolic/diastolic (r = 0.591 and 0.587 respectively) and for daytime ABPM vs mean OBP systolic/diastolic (r = 0.173 and 0.306 respectively) .
To the best of our knowledge, this is the first study conducted on Egyptian hypertensive patients using the unattended ASqBP device which revealed good correlations with AMBP and emphasized that we should not only depend on OBP readings for diagnosis and follow-up medications. Meanwhile, ASqBP might be beneficial in two aspects. First, it may be cost effective by decreasing the need of ambulatory blood pressure reducing the cost of its use and decreasing the number of visits to outpatient clinics. Second, it can help to reduce physician patient contact during office visits in the current era of COVID-19.
Temporal timing of BP measurements is considered a limitation of our study. During office visit, we recorded OBP and ASqBP readings, while AMBP recording was done either on the same day or within 48 h from the office measurement, which could bias BP readings. Another limitation is the small number of the patient in the study.