Blood Pressure Variability Between In-Clinic and At-Home Measurements: Implications for Care Quality Assessment

Nearly half of American adults live with high blood pressure, of whom three-quarters do not have their blood pressure under adequate control. Many challenges exist in assessing blood pressure control, including in-clinic measurement biases and physiologic variability, limiting the ability to appropriately guide therapeutic changes.

This study's objective was to compare blood pressure (BP) variability in-clinic and at-home using a BP monitoring app.

This retrospective, observational study compared in-clinic BP measurements to at-home BP measurements recorded via a mobile application from April 2024 to May 2025. BP variability was assessed, comparing standard deviations (SD), control status (adequately controlled: systolic BP < 140 mmHg and diastolic BP < 90 mmHg), and both within-day and within-week timeframe fluctuations.

Among 304 patients with sufficient in-clinic data, the mean SD value for in-clinic systolic BP was 12.6 mmHg. Comparing at-home readings 2, 4, and 6 weeks before an in-clinic appointment for 207, 229, and 243 patients with sufficient data, 71.5%, 72.1%, and 72.8% of in-clinic measurements differed by more than 5 mmHg from average at-home systolic BP, and 30.1%, 29.8%, and 29.8% indicated a different hypertension control status, respectively. For patients with at-home readings, the mean systolic BP SD for 288 patients within the same day was 8.8 mmHg. Over 2, 4, and 6 week timeframes, mean SD increased to 10.5, 10.9, and 11.1 mmHg for 322, 329, and 336 patients with sufficient readings, respectively.

Reliance on single in-clinic BP measurements for hypertension management can be inaccurate due to significant variability over time. In addition to impacting treatment decisions, this may impact HEDIS metrics and Medicare Advantage Star ratings, which heavily influence healthcare revenue and quality perception. Findings indicate at-home BP monitoring can result in a meaningfully different BP control rate, emphasizing a role for at-home monitoring to enhance BP measurement reliability.