Achtergrond:
Bij volwassenen ouder dan 35 jaar ontwikkelen 37% van de prehypertensieve patiënten (een bloeddruk van 130-139/86-89 mm Hg) uiteindelijk hypertensie, net zoals 17% van dezelfde leeftijdsgroep met een normale bloeddruk. Ouderen hebben een risico van meer dan 90% om in hun verdere leven hypertensie te ontwikkelen. Studies met prehypertensiepatiënten hebben tot nu toe inhomogene resultaten opgeleverd. Hierom besloten de auteurs een meta-analyse te verrichten.

Methoden:
Data tot 1950 leverden 25 klinische trials welke geschikt waren voor inclusie in de analyse, uit 874 gereviewde abstracts. De onderzoekers includeerden alleen gerandomiseerde trials voor antihypertensieve behandeling voor primaire of secundaire preventie op CV events met een bloeddruk lager dan 140/90 mm Hg. In totaal werden er 64.162 patiënten geïncludeerd met een follow-up duur van 1,5 tot 63 maanden. Inclusiecriteria varieerden, maar allen hadden een voorgeschiedenis in CV aandoeningen: klinisch bewijs van recente stroke, myocardinfarct, hartfalen of coronairlijden. Het type antihypertensieve medicatie varieerde eveneens en omvatte betablokkers, calciumantagonisten, ACE remmers, ARBs en diuretica.
 

Resultaten:

Bij alle eindpunten behalve bij het myocardinfarct werden statistisch significante voordelen gezien ten gunste van digene die antihypertensieve therapie ontvingen. De meta-analyse werd beperkt door gebrek aan baseline gegevens, misclassificatie als gevolg van verschilllende technieken waarmee de bloeddruk vastgesteld werd.

Conclusie:
De studie wijzen op een mogelijk voordeel van antihypertensieve therapie voor de preventie van CV events en sterfte. De grootte van het effect varieerden tussen een reductie van 13% in sterfte als gevolg van elke oorzaak tot een reductie van 29% op het risico op congestief hartfalen.

Lees onderstaand het volledige artikel.
 

BP Drugs May Help in Normotensive CVD Patients

Normotensive patients with cardiovascular disease (CVD) had a significant reduction in the risk of cardiovascular events and mortality when treated with antihypertensive drugs, according to a meta-analysis.

The spectrum of the benefit encompassed a composite clinical endpoint as well as every type of event included in the composite. The magnitude of the effect ranged from a 13% reduction in the hazard for all-cause mortality to a 29% reduction in the risk of congestive heart failure (CHF), as reported in the March 2 issue of JAMA.

"The results of this meta-analysis suggest that persons with these compelling indications but without hypertension may also benefit from reduced morbidity and mortality attributable to CVD events when treated with antihypertensive medications," Angela M. Thompson, MSPH, of the Tulane University of School of Public Health and Tropical Medicine in New Orleans, and co-authors wrote in conclusion. They urged additional studies "to determine if there is benefit of treating prehypertension at levels less than 140/90 mm Hg in populations with these risk factors." Among adults 35 and older, 37% in the prehypertensive range (130-139/86-89 mm Hg) progress to hypertension within four years, as do 17% of the same age group with normal blood pressure (Lancet 2001; 358: 1682-1686). Adults 55 and older have more than a 90% lifetime risk of developing hypertension, the authors noted.

Studies involving patients with prehypertension have yielded mixed results for antihypertensive therapy, an uncertainty that prompted Thompson and co-authors to examine clinical-trial data via meta-analysis.

A search of published medical literature dating back to 1950 revealed 25 clinical trials suitable for inclusion in the analysis from 874 abstracts reviewed.

The investigators included only randomized, controlled trials of antihypertensive treatment for primary or secondary prevention of CVD events in patients with blood pressure less than 140/90 mm Hg. The trials involved a total of 64,162 patients with average follow-up of 1.5 to 63 months.

Entry criteria for the individual trials varied, but all required a history of CVD; clinical evidence of recent stroke, myocardial infarction (MI), CHF, or coronary artery disease; or CVD equivalent, such as type 2 diabetes.

The type of antihypertensive medication also varied and included beta-blockers, calcium-channel antagonists, ACE inhibitors, angiotensin-receptor blockers, and diuretics.

As compared with control groups, patients treated with antihypertensives had significant cumulative reductions in the relative risk of:

• Stroke (HR 0.77, 0.61 to 0.98)
• MI (HR 0.80, 0.69 to 0.93)
• CHF (HR 0.71, 0.65 to 0.77)
• Composite CVD events (HR 0.85, 0.80 to 0.90)
• CVD mortality (HR 0.83, 0.69 to 0.99)
• All-cause mortality (HR 0.87, 0.80 to 0.95)

Absolute reductions -- expressed as events per 1,000 persons -- showed statistically significant advantages in favor of antihypertensive therapy for all endpoints except MI (-13.3, -28.4 to +1.7). The investigators noted that the meta-analysis was limited by the lack of baseline blood pressure data, possible misclassification due to different techniques of blood pressure measurement, potential confounding due to differential loss to follow-up, and lack of event numbers in some studies that led to event estimates from other data in the trials. The findings clearly indicate a significant clinical benefit of antihypertensive therapy for patients with CVD and blood pressure <140/90 mm Hg, according to the authors of an accompanying editorial.

However, the analysis did not demonstrate whether the observed benefits resulted from blood-pressure lowering or some other mechanism of the drugs, wrote Hector Ventura, MD, of the John Ochsner Heart and Vascular Institute in New Orleans, and Carl Lavie, MD, of the University of Queensland in Brisbane, Australia. Less clear are the implications for patients without CVD.

"Patients with prehypertension who do not have CVD are at increased risk of developing hypertension with associated increases in cardiovascular morbidity and mortality, but the benefits compared with the risks and costs of pharmacological treatments in this group have not been fully assessed," Ventura and Lavie wrote. "To reach firmer conclusions will require more data from randomized trials involving patients with [blood pressure] levels less than 140/90 mm Hg to evaluate the effects of pharmacological therapies on preventing CVD outcomes," they added.