Hypertension and prehypertension often go undiagnosed in children and adolescents, a new US study suggests.

In the cohort study published in the Journal of the American Medical Association (JAMA: 2007;298:874-879), just 26% (131) of 507 children and adolescents meeting the criteria for hypertension had a diagnosis of the condition or elevated blood pressure documented in the electronic medical record (EMR). Only 11% or 55 of the 485 children and adolescents found to have prehypertension showed an appropriate diagnosis in the EMR.

A US team led by Dr Matthew Hansen of Case Western Reserve University in Cleveland, Ohio looked at 14,187 children and adolescents aged three to 18 years who were observed at least three times for well-child care in outpatient clinics in northeast Ohio between June 1999 and September 2006.

For children and adolescents with elevated age-adjusted and height-adjusted blood pressure measurements at three or more of these visits, the researchers determined the proportion with a hypertension-related International Classification of Diseases, Ninth Revision code in the diagnoses list, problem list or past medical history list of any visit.

Patient factors that significantly increased the likelihood of a correct diagnosis for hypertension were a one-year increase in age over three years old; the number of elevated blood pressure readings above three; an increase of 1% in the height-for-age percentile; having an obesity-related diagnosis; and the number of blood pressure readings in the stage 2 hypertension range.

For prehypertension, patient factors that significantly raised the odds of a correct diagnosis included a one-year increase in age over three years old; and the number of elevated blood pressure readings above three.

Common problem

As the JAMA article points out, hypertension is a common chronic disease in children, with an estimated prevalence of 2-5%. This figure is increasing in line with an epidemic of paediatric obesity. Diagnosis of hypertension in children is complicated, as normal and abnormal bloods pressure values vary with age, sex and height, the authors note.

Identifying elevated blood pressure in children is important not only because of the growing prevalence of paediatric weight problems but also because secondary hypertension is more common in children than adults, they comment. “If abnormal blood pressure is not identified by a patient’s paediatric clinician, it may be years before the abnormal blood pressure is detected, leading to end-organ damage,” the researchers add. “Because effective treatments for abnormal blood pressure exist, these long-term sequelae can be avoided with early diagnosis.”

The problem with under-diagnosis could be remedied through a clinical decision support algorithm, built into the electronic medical record, that would automatically review current and prior blood pressure, age, height and sex to determine whether the criteria for abnormal blood pressure were met, the authors suggest. The same algorithm could provide physicians with guideline-based evaluation, treatment and parent/patient education materials.