Millions in England May Have Undiagnosed Hypertension, Study Estimates

More than four million people in England are estimated to have high blood pressure without knowing it, according to a cross-sectional study published in PLOS One that applied a statistical correction for the gap between clinic and out-of-office blood pressure readings.

The study addressed a long-standing measurement problem in hypertension epidemiology. Blood pressure readings taken in a clinic setting can differ systematically from those taken out of office, meaning that simple counts of elevated clinic readings may overestimate or underestimate the true number of people with hypertension. To account for this, the team applied a validated algorithm called Predicting Out-of-Office Blood Pressure (PROOF-BP), which estimates what a person’s out-of-office blood pressure is likely to be based on clinic measurements. Observed blood pressure was defined as the mean of the second and third measurements taken at a Health Survey visit, and predicted hypertension was calculated using the PROOF-BP estimates, with a diagnostic threshold of 135/85 mmHg for the primary out-of-office outcome and 140/90 mmHg as a secondary threshold.

Using observed clinic measurements alone, the prevalence of undiagnosed hypertension in the study population was 27.7 percent (95 percent confidence interval 26.4 to 29.1 percent). After adjustment with the PROOF-BP algorithm, the predicted prevalence fell to 21.8 percent (95 percent confidence interval 20.6 to 23.0 percent). The difference illustrates how much of the apparent undiagnosed burden in clinic-based counts may reflect measurement variation rather than genuinely elevated out-of-office blood pressure.

The adjusted estimates revealed marked demographic and geographic patterns. Predicted prevalence was nearly double in males, at 29.8 percent (95 percent confidence interval 27.8 to 32.0 percent), compared with 14.6 percent in females (95 percent confidence interval 13.3 to 15.9 percent). Prevalence also varied by region, ranging from 26.3 percent in the West Midlands (95 percent confidence interval 22.2 to 31.0 percent) to 16.9 percent in London (95 percent confidence interval 13.5 to 20.9 percent). Weighted prevalence estimates were presented by age, sex and geographical region.

Extrapolating the adjusted estimates to the total English population aged 40 and over using national population statistics, the researchers estimate that approximately 4.2 million people in England are unaware of their hypertension.

The authors note that hypertension case-finding and management is key to reducing premature morbidity and mortality. In England, 14.8 percent of people receive treatment for hypertension, but the total number of hypertensive individuals has remained unclear because it can only be estimated statistically. The study’s refined analytical approach, the authors write, provides a more precise estimate of the undiagnosed population and is intended to support targeted public health initiatives to identify and address undiagnosed cases.

As a cross-sectional analysis of survey data, the study provides prevalence estimates for a specific period and population rather than tracking changes over time, and its national figures depend on the accuracy of the PROOF-BP algorithm and the extrapolation from the survey sample to the wider English population aged 40 and over.

Subject of Research: Estimating the prevalence of undiagnosed hypertension among adults in England using measurement error adjustment

Article Title: Measurement error adjusted prevalence of undiagnosed hypertension in England: A cross-sectional study

Article References: Castanon, A., Hughes, A., Grasic, K., White, M., Sheppard, J. P., McManus, R. J., Pearson-Stuttard, J., & Stevens, R. (2026). Measurement error adjusted prevalence of undiagnosed hypertension in England: A cross-sectional study. PLOS One, 21(10), e0359861. https://doi.org/10.1371/journal.pone.0359861

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0359861

Keywords: hypertension, blood pressure, undiagnosed hypertension, England, Health Survey for England, PROOF-BP, cross-sectional study, public health, case-finding, prevalence, PLOS One, Measurement