Diagnostic Accuracy of Unattended Automated Office Blood Pressure Measurement in Screening for Hypertension in Kenya

Abstract

Despite increasing adoption of unattended automated office blood pressure (uAOBP) measurement for determining clinic blood pressure (BP), its diagnostic performance in screening for hypertension in low-income settings has not been determined. We determined the validity of uAOBP in screening for hypertension, using 24-hour ambulatory BP monitoring as the reference standard. We studied a random population sample of 982 Kenyan adults; mean age, 42 years; 60% women; 2% with diabetes mellitus; none taking antihypertensive medications. We calculated sensitivity using 3 different screen positivity cutoffs (≥130/80, ≥135/85, and ≥140/90 mm Hg) and other measures of validity/agreement. Mean 24-hour ambulatory BP monitoring systolic BP was similar to mean uAOBP systolic BP (mean difference, 0.6 mm Hg; 95% CI, −0.6 to 1.9), but the 95% limits of agreement were wide (−39 to 40 mm Hg). Overall discriminatory accuracy of uAOBP was the same (area under receiver operating characteristic curves, 0.66–0.68; 95% CI range, 0.64–0.71) irrespective of uAOBP cutoffs used. Sensitivity of uAOBP displayed an inverse association ( P <0.001) with the cutoff selected, progressively decreasing from 67% (95% CI, 62–72) when using a cutoff of ≥130/80 mm Hg to 55% (95% CI, 49–60) at ≥135/85 mm Hg to 44% (95% CI, 39–49) at ≥140/90 mm Hg. Diagnostic performance was significantly better ( P <0.001) in overweight and obese individuals (body mass index, >25 kg/m 2 ). No differences in results were present in other subanalyses. uAOBP misclassifies significant proportions of individuals undergoing screening for hypertension in Kenya. Additional studies on how to improve screening strategies in this setting are needed.

Does This Adult Patient Have Hypertension?

“…The searches identified 12 604 titles, of which 17 articles ultimately met the inclusion criteria (Table 3 and Table 4; eFigure in the Supplement). Nine studies (n = 4368) compared office or home measures with mean BP while awake during ABPM as the reference standard, 5 studies (n = 3191) compared results with mean BP during 24-hour ABPM, and 2 studies (n = 1183) compared results with both mean BP while awake during ABPM and mean BP during 24-hour ABPM …”

In-office and out-of-office blood pressure measurement

“… Items AOBP with antecedent rest time ACC/AHA 2017 [ 3 ] ESC/ESH 2018 [ 2 ] JSH 2019 [ 1 ] 2020 ISH [ 4 ] Before the measurement Rest period 5 min >5 min 5 min A few min 3–5 min Medical staff Absent N/A (present) N/A (present) N/A (present) N/A (present) Inspection the measurement No; instructed before the start, and left alone All All All All During the measurement Interval 1 min 1–2 min 1–2 min 1–2 min 1 min Medical staff Absent N/A (present) N/A (present) N/A (present) N/A (present) Measurement times ≥3 ≥2 3; additionally 1 when the first and second readings differ by >10 mmHg ≥2; 3 when a person is a child, or has arrhythmia or other conditions 3, or 1 if the first reading is <130/85 mmHg Average the readings All ≥2 readings obtained on ≥2 occasions The last 2 readings 2 readings with ≤5 mmHg difference The last 2 readings Conditions are applicable for measurements using an automated device. The measurement condition of automated office blood pressure (AOBP) was expanded from the original definitions to include 5 min antecedent time and average all the three measurements, which was used in the recent studies [ 7 – 9 ]. JSH 2019, ACC/AHA 2017, ESC/ESH 2018, and 2020 ISH denote the Japanese Society of Hypertension Guidelines for the Management of Hypertension (JSH 2019), the 2017 American College of Cardiology/American Heart Association Guidelines, the 2018 European Society of Cardiology/European Society of Hypertension Guidelines, and the 2020 International Society of Hypertension Global Hypertension Practice Guidelines, respectively.…”

“… Conditions are applicable for measurements using an automated device. The measurement condition of automated office blood pressure (AOBP) was expanded from the original definitions to include 5 min antecedent time and average all the three measurements, which was used in the recent studies [ 7 – 9 ]. JSH 2019, ACC/AHA 2017, ESC/ESH 2018, and 2020 ISH denote the Japanese Society of Hypertension Guidelines for the Management of Hypertension (JSH 2019), the 2017 American College of Cardiology/American Heart Association Guidelines, the 2018 European Society of Cardiology/European Society of Hypertension Guidelines, and the 2020 International Society of Hypertension Global Hypertension Practice Guidelines, respectively.…”

“…AOBP was initially defined as office blood pressure measured by an automated device for multiple readings (three times or more [ 5 ]), recorded automatically with the patient under rest in an undisturbed quiet room in the absence of an observer [ 5 , 6 ]. Five minutes of rest in the unattended setting before AOBP measurement has been further used in many recent studies (Table 1 ) [ 7 – 9 ]. Stults et al raised concern about inhabitation of AOBP utilization in real-world settings [ 10 ]; the AOBP including antecedent rest time requires >10 min per person, which includes a few minutes for preparation and clean up.…”

“…Recent studies reported that average levels of AOBP were similar to the 24-h ambulatory blood pressure in a population [ 9 , 13 ]. However, we cannot conclude that AOBP can alter the out-of-office measurement because the variation in differences by individuals should not be ignored.…”