Childhood Hypertension Usually Goes Undiagnosed

BOSTON, Aug. 21 -- Childhood hypertension is there, if only pediatricians would look for it.

So concluded investigators here who found that only a quarter of children and adolescents with hypertension had a diagnosis or documentation of elevated blood pressure in their electronic medical records.

Even fewer prehypertensive children and adolescents had the condition noted in their records, David C. Kaelber, M.D., Ph.D., of Boston Children's Hospital and Harvard, and colleagues, reported in the Aug. 22 issue of the Journal of the American Medical Association.

"Based on the data in this study, these conditions appear to be frequently undiagnosed by pediatric clinicians," the authors concluded. "Early, appropriate diagnosis is important because established evaluation guidelines and effective treatment for abnormal blood pressure exist."

Yet recent evidence indicates that blood pressure in children and adolescents is increasing with body weight, noted the authors. Although long-term sequelae of hypertension, such as myocardial infarction and heart failure, rarely manifest in children, hypertension in childhood predicts hypertension in adulthood. Moreover, childhood hypertension has been associated with early markers of cardiovascular disease, such as left ventricular hypertrophy.

To assess the frequency of undiagnosed hypertension in children and adolescents, Dr. Kaelber and colleagues reviewed electronic medical records within a large academic medical center. They identified, 14,187 patients ages three to 18 years who had at least three well-care visits from June 1999 to September 2006.

The investigators defined childhood hypertension according to consensus criteria of blood pressure at or beyond the 95^th percentile for age, sex, and height on three different occasions. Prehypertension was defined as blood pressure at the 90^th percentile or higher on three occasions or 120/80 mm Hg but less than the 95^th percentile.

The analysis revealed 507 children and adolescents with hypertension and 485 who had prehypertension. Adolescents made up about 3.5% of the hypertensive and prehypertensive patients. Electronic medical records included a diagnosis of hypertension or documentation of elevated blood pressure in 131 (26%) of the hypertensive patients. Of the prehypertensive group, 55 (11%) had an appropriate diagnosis in their electronic medical records.

Factors that increased the likelihood of a hypertension diagnosis were:

• Each one-year increase in age beyond three.
• More than three elevated blood pressure readings.
• A 1% increase in height-for-age blood pressure percentile.
• An obesity-related diagnosis.
• Number of blood pressure readings in the stage 2 hypertension range.

A prehypertension diagnosis was more likely to be noted with each one-year increase in age and the number of elevated blood pressure readings beyond three.

The authors offered two possible clinician-related factors that might explain the low diagnostic rates for hypertension and prehypertension. One was the lack of knowledge of normal blood pressure ranges and the other was the lack of awareness of a patient's previous blood pressure readings. They noted that blood pressure was documented in 94% of all the well-care visits.

The authors noted several limitations to the study. These included no examination of physician traits potentially related to blood pressure assessment and diagnosis; reliance solely on well-care visits; absence of a standardized protocol for measuring blood pressure; and accuracy of blood pressure measurements.

However, the investigators asserted, "Our study represents true underdiagnosis of hypertension as these patients' hypertension was not recognized by clinicians throughout our health care system."