Impact Of Ambulatory Blood Pressure Monitoring On Hypertension Diagnosis In Primary Care

Introduction: Hypertension (HTN) screening guidelines recommend using ambulatory blood pressure monitoring (ABPM) to exclude white coat HTN prior to newly diagnosing HTN. Yet, little is known about the impact of ABPM testing on HTN diagnosis decisions in primary care. Unfamiliarity with how to interpret ABPM results could lead to overtreatment or diagnostic inertia, the failure to diagnose a disease despite clinical evidence. Methods: We examined medical records of primary care patients with elevated office BP (≥140/90 mmHg) who were referred to an ABPM testing service. Patients were eligible for analysis if they were ≥18 years old, had elevated office BP without a HTN diagnosis and not prescribed BP medications, were referred by a primary care clinician from clinics affiliated with Columbia University Medical Center, and completed ABPM testing between 2016-2019. Using mean awake BP of 135/85 mmHg as the threshold for elevated ABPM, we compared the BP testing outcome (white coat HTN, in which only office BP was elevated, or sustained HTN, in which both office and ambulatory BP were elevated) to the physician’s action at the subsequent scheduled primary care visit (diagnosed or did not diagnose HTN per manual review of electronic medical records). Results: Overall, 111 patients with newly elevated office BP completed ABPM testing during the analysis period. Patients were referred by 60 physicians (50% trainees) from 6 clinics. Patients had a mean (SD) age of 53 (15) years; 73% were women. Fifty-nine patients (53%) had white coat HTN, and 52 (88%) were not diagnosed with HTN at their next primary care visit. The remaining 52 patients (47%) had sustained HTN, and 44 (85%) were diagnosed with HTN at their next visit. Medication was started for 31 of these 44 (70%). Overall, physicians diagnosed HTN concordantly with ABPM results for 96/111 patients (86%). Conclusions: More than half of primary care patients with elevated office BP referred for ABPM had white coat HTN. There was high concordance between ABPM results and physician HTN diagnoses, suggesting that ABPM reduces but does not eliminate overdiagnosis and diagnostic inertia in HTN. More research is needed to understand the reasons for discordance and how to optimize the implementation of ABPM testing into primary care.