More New Guidelines, Antihypertensive Medications
After the onslaught of national hypertension guidelines that followed the ALLHAT results and the US JNC 7 hypertension guidelines, the focus this month was on children and adolescents in the new pediatric guidelines. There was also a critical look at whether all thiazide diuretics are really equivalent (chlorthalidone vs hydrochlorothiazide), and the efficacy of a fixed combination of 2 established therapies, a CCB plus a statin, was evaluated. Early research results with several new approaches to antihypertensive drugs, including a nonpeptide renin inhibitor, an advanced glycation end product (AGE) cross-link breaker, and a low-dose combination preparation of a novel progestin, have been reported. Finally, more data on special populations, in this case American blacks and ischemic stroke patients.

New national guidelines for the diagnosis and treatment of hypertension in children are to be issued shortly in the United States by the National Heart, Lung, and Blood Institute (NHLBI) and the National High Blood Pressure Education Program (NHBPEP). An advance overview of the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents was given at the 19th Scientific Meeting of the American Society of Hypertension, held May 18-22 in New York City, by Bonita Falkner, MD (Thomas Jefferson University, Philadelphia, Pennsylvania), chair of the NHBPEP Working Group on High Blood Pressure in Children and Adolescents. The working group's full report will be published in Pediatrics and on the NHLBI Web site. The report updates the previous guidelines, published in 1996, and is based on the latest data from the National Health and Nutrition Examination Survey (NHANES) conducted in 1999 and 2000. It conforms to the most recent US national hypertension guidelines for adults, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), issued last year.

Hypertension in children is defined by percentiles – ie, assigning a percentage value to a child's blood pressure based on the percentage of the reference population with a lower pressure vs the percentage with a higher pressure. This is necessary in order to take into account the large variations in body weight, height, age, and other developmental parameters inherent in young patients.

The new, updated blood pressure tables have added the 50th and 99th percentiles to the 90th and 95th percentiles that were included in previous reports. The 50th percentile defines the midpoint of the normal blood pressure range, and the 99th percentile allows more precise staging of hypertension, which is defined as > 95th percentile.

The new blood pressure classification also introduces the "prehypertension" category first used in JNC 7; here, it is defined in children as average systolic/diastolic blood pressure (SBP/DBP) ≥ 90th and < 95th percentile. The definition of hypertension remains unchanged, at SBP and/or DBP ≥ 95th percentile for age, gender, and height measured on ≥ 3 separate occasions. Adolescents with blood pressure ≥ 120/80 mm Hg should also be considered hypertensive. For stage 1 hypertension, an additional 5 mm Hg is added to the 95th to 99th percentile blood pressures, and it is considered stage 2 hypertension when an extra 5 mmHg or more is added to the > 99th percentile ranges ( Table 1 ).

The white coat hypertension syndrome has been acknowledged in children for the first time. It is defined as an individual whose blood pressure is > 95th percentile in the physician's office or clinic but who is normotensive outside this setting.

The NHBPEP report recommends that blood pressure should be measured in children aged ≥ 3 years; measurement should start earlier in preterm infants. The report recommends that weight and diet management, introduction of physical activity, and counseling for the overweight should be "instituted or strongly encouraged" in children who are prehypertensive and as initial therapy in those who are hypertensive. Pharmacologic therapy may be appropriate for prehypertension if there are compelling indications such as renal disease, diabetes, or signs of left ventricular hypertrophy, the report says. Pharmacologic therapy should be initiated in stage 1 and in stage 2 unless there is a dramatic response to lifestyle changes. Pharmacologic therapy should begin with a single drug such as an angiotensin-converting enzyme (ACE) inhibitor, angiotensin receptor blocker, beta-blocker, calcium channel blocker (CCB), or diuretic.

Recommendations are given for identification of comorbidities, ie, associated risk factors for cardiovascular disease, particularly obesity, lipid disorders, glucose metabolism abnormalities including familial history of diabetes, and sleep disorders. The report also recommends that children should be evaluated for target organ damage. Ideally, children should have an echocardiogram to detect any left ventricular hypertrophy as part of their evaluation.

In the May 20 issue of The New England Journal of Medicine, deputy editor Julie R Ingelfinger, MD (Harvard Medical School and Massachusetts General Hospital for Children; Boston), who was a member of the guidelines working group, stresses the importance and potential benefits of early recognition of hypertension for introducing early interventions and reducing cardiovascular mortality among adults. She defends the use of the term prehypertension in children and adolescents as serving as "a signal to institute healthful lifestyle changes that might avert future cardiovascular disease." While admitting that "many physicians are still not familiar with the best way to evaluate and treat children with high blood pressure," she is hopeful that the working group's new report will "constitute a call to action."

A recent analysis of data from NHANES III (1988-1994) and NHANES 1999-2000 by researchers at Tulane University (New Orleans, Louisiana) and the NHLBI (Bethesda, Maryland) showed that blood pressure in US children and adolescents rose between the time of the two surveys. The rise in DBP (an average of 2.2 mm Hg) was particularly large, while SBP rose by an average of 1.4 mm Hg. A strong association between body mass index (BMI) and SBP identified among children suggests that this increase in blood pressure is at least in part attributable to an increased prevalence of overweight.