Diagnostic performance of an automatic blood pressure measurement device, Microlife WatchBP Home A, for atrial fibrillation screening in a real-world primary care setting

Objective To evaluate the diagnostic performance of a UK National Institute for Health and Care Excellencerecommended automatic oscillometric blood pressure (BP) measurement device incorporated with an atrial fibrillation (AF) detection algorithm (Microlife WatchBP Home A) for real-world AF screening in a primary healthcare setting. Setting Primary healthcare setting in Hong Kong. Interventions This was a prospective AF screening study carried out between 1 September 2014 and 14 January 2015. The Microlife device was evaluated for AF detection and compared with a reference standard of lead-I ECG. Primary outcome measures Diagnostic performance of Microlife for AF detection. Results 5969 patients (mean age: 67.2 +/- 11.0 years; 53.9% female) were recruited. The mean CHA 2 DS 2-VASc (C: congestive heart failure [1 point]; (H) under bar: hypertension [1 point]; (A) under bar2 : age 65-74 years [1 point] and age >= 75 years [2 points]; (D) under bar: diabetes mellitus [1 point]; (S) under bar: prior stroke or transient ischemic attack [2 points]; (VA) under bar: vascular disease [1 point]; and (Sc) under bar: sex category [female] [1 point]) score was 2.8 +/- 1.3. AF was diagnosed in 72 patients (1.21%) and confirmed by a 12-lead ECG. The Microlife device correctly identified AF in 58 patients and produced 79 false-positives. The corresponding sensitivity and specificity for AF detection were 80.6% (95% CI 69.5 to 88.9) and 98.7% (95% CI 98.3 to 98.9), respectively. Among patients with a false-positive by the Microlife device, 30.4% had sinus rhythm, 35.4% had sinus arrhythmia and 29.1% exhibited premature atrial complexes. With the low prevalence of AF in this population, the positive and negative predictive values of Microlife device for AF detection were 42.4% (95% CI 34.0 to 51.2) and 99.8% (95% CI 99.6 to 99.9), respectively. The overall diagnostic performance of Microlife device to detect AF as determined by area under the curves was 0.90 (95% CI 0.89 to 0.90). Conclusions In the primary care setting, Microlife WatchBP Home was an effective means to screen for AF, with a reasonable sensitivity of 80.6% and a high negative predictive value of 99.8%, in addition to its routine function of BP measurement. In a younger patient population aged < 65 years with a lower prevalence of AF, Microlife WatchBP Home A demonstrated a similar diagnostic accuracy.