Large Proportion of Hospitalized Patients May Have Undiagnosed Hypertension

Hospital COVID
A large retrospective observational study found large numbers of hospitalized patients with blood pressures exceeding thresholds for hypertension.

A large number of hospitalized patients in the United Kingdom were found to have mean blood pressures that exceeded the diagnostic threshold for hypertension, without any notation of treatment or diagnosis of hypertension on their medical records, according to findings published in the American Journal of Hypertension.

Hypertension is a major cause of mortality and morbidity, and its prevalence in both diagnosed and undiagnosed states in community populations has been widely reported. However, estimates for prevalence among hospitalized patients in a UK hospital setting, whose average blood pressure readings meet the current international guidelines for a diagnosis of hypertension, are lacking. Investigators sought to find these data through a retrospective cross-sectional observational study of adult patients (N=41,455, aged 16 and older) admitted to 4 acute care hospitals between March of 2014 and April of 2018. To be eligible for this study, patients needed to have at least 3 blood pressure readings recorded during their stay, with 2 of these taken at least 24 hours apart.

A total of 1.7 million blood pressure measurements were recorded among the 41,455 eligible hospital inpatients included in the study. Of these, 21.4% had a mean blood pressure exceeding the diagnostic threshold for hypertension at either Stage 1, 2, or 3, according to the European Society of Cardiology (ESC) and the European Society of Hypertension (ESH) diagnostic criteria. Over 40% of these patients exceeded the diagnostic threshold according to American College of Cardiology (ACC)/American Heart Association (AHA) diagnostic criteria.

Among the total patients, 5% of men and 5% of women met the ESC/ESH diagnostic criteria for hypertension but had no preexisting diagnostic code for hypertension on record, nor any antihypertensive medication prescribed during their hospital stay (14% men and 12% women according to ACC/AHA criteria).

As a retrospective observational study, there are some inherent limitations. One of the most notable limitations of this study is that by requiring multiple blood pressure readings, the possibility of selection bias is introduced, as the patients with longer stays and/or troubling readings will have their blood pressure taken and recorded more often. Nevertheless, study investigators concluded, “A substantial number of [hospitalized] patients have an average in-hospital [blood pressure] that exceeds international criteria for the diagnosis of hypertension, with many demonstrating isolated nocturnal hypertension that are unlikely to be picked up with clinic or home [blood pressure] measurements. In-hospital [blood pressures] may present an opportunity to detect patients with previously undiagnosed hypertension.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Mahdi A, Armitage LC, Tarassenko L, Watkinson P. Estimated prevalence of hypertension and undiagnosed hypertension in a large inpatient population: a cross-sectional observational study [published online May 22, 2021]. Am J Hypertens. doi:10.1093/ajh/hpab070