Education on Use of ABPM Data Needed in Primary Care to Avoid Misdiagnosis of Hypertension

More than half of primary care patients with elevated office blood pressure (BP) were found to have white coat hypertension (HTN) when referred for ambulatory BP monitoring (ABPM), according to new study findings.

And although they found concordance high between ABPM results and a subsequent clinical diagnosis of HTN, study authors remain concerned about the potential for HTN over- and underdiagnosis in primary care. The study was presented this week at the American Heart Association Hypertension 2022 Scientific Sessions

As background for the research, investigators, led by Ian Kronish, MD, MPH, associate professor of medicine, Columbia University Irving Medical Center (CUIMC), associate director of the Center for Behavioral Cardiovascular Health, and codirector of the Hypertension Center at CUIMC, cite the recommendation by hypertension screening guidelines that ABPM be used routinely to rule out white coat HTN before making a diagnosis of HTN and initiating pharmacologic treatment. Research is sparse, the team notes, on what impact ABPM results have on HTN diagnosis decisions in primary care and inexperience in ABPM interpretation could lead to either unneeded treatment or diagnostic inertia.

To learn more about how primary care clinicians square ABPM results with initial clinic BP readings, the researchers examined medical records of primary care patients with newly elevated office BP (≥140/90 mmHg) who were referred to an ABPM testing service by a primary care professional from clinics affiliated with Columbia University Medical Center. Patients eligible for the analysis were ≥18 years old, had elevated office BP but were not diagnosed with HTN and were not prescribed antihypertensive medications. All patients had completed ABPM testing between 2016 and 2019.

Research is sparse, the team notes, on what impact ABPM results have on HTN diagnosis decisions in primary care and inexperience in ABPM interpretation could lead to either unneeded treatment or diagnostic inertia.

The threshold established for elevated ABPM was mean awake BP of 135/85 mm Hg. Investigators compared the outcome of BP testing—white coat HTN (only office BP elevated) or sustained HTN (both office and ambulatory BP elevated) to medical records of action taken at the subsequent scheduled primary care visit—did or did not diagnose HTN.

A total of 111 primary care patients with newly recorded elevated office BP completed ABPM during the 3-year analysis period. In all, 60 primary care clinicians from 6 participating clinics referred patients; 50% of those clinicians were “trainees,” according to the study abstract.

The mean age of the cohort was 53 years and 73% were women.

FINDINGS

• 59 patients (53%) had white coat HTN and 52 patients (88%) were not diagnosed with HTN at their next primary care visit.
• The 52 remaining patients (47%) had sustained HTN, and 44 (85%) were diagnosed with HTN at their next visit.
• Antihypertensive medication was initiated for 31 of the 44 (70%) given a diagnosis of HTN.

Overall, Kronish and colleagues report, primary care clinician diagnosis of HTN was concordant with ABPM results for 96/111 patients (86%).

More than half of this cohort of primary care patients with elevated office BP were found to have white coat HTN when referred for ABPM, the research team summarizes in the study abstract. The high concordance between ABPM results and diagnosis of HTN by participating clinicians, the authors write, suggests that ABPM reduces but does not eliminate the tendency toward overdiagnosis and diagnostic inertia of HTN. “More research is needed to understand the reasons for discordance and how to optimize the implementation of ABPM testing into primary care,” they conclude.

Reference: Flatow J, Sanchez J, Singer J, et al. Impact of ambulatory blood pressure monitoring on hypertension diagnosis in primary care. Hypertension. 2022;79:A086. Published online September 7, 2022. doi:10.1161/hyp.79.suppl_1.086