Is prevention of vascular dementia possible? The Syst-Eur Vascular Dementia Project

Clinical trial experience around the globe: focus on calcium-channel blockers

Although certain classes of drugs appear to possess benefits apart from their blood-pressure lowering capability, reduction of blood pressure remains the single most important action of antihypertensive therapy. Calcium-channel blockers (CCBs) have long been recognized as potent agents for hypertension therapy. This is especially true for the prevention of stroke in hypertensive patients as evidenced from the Systolic Hypertension in Europe (Syst-Eur) and Systolic Hypertension in China (Syst-China) trials with a long acting dihydropyridine CCB. The same can be said for beta blockers in patients post myocardial infarction. However, most recent clinical trials have underscored the necessity of multiple drug therapy to achieve the goals of blood pressure reduction coupled with outcomes reduction. For example, the many recent large-scale clinical trials have required an average of three or more agents to achieve goal. Thus, the paradigm for hypertension management has been altered to determine the best treatment regimen rather than the best initial agent. While response rates to individual agents across a wide spectrum of patients vary little, not all drugs are equally suited as companion products. In this article, we discuss the most recent outcome trials with the long acting CCBs alone or in combination with other drugs. The evidence shows that calcium antagonists remain an important part of hypertension management, including in those individuals at risk of cardiac and cerebrovascular events.

Improved outcomes with antihypertensive medication in the elderly with isolated systolic hypertension

Isolated systolic hypertension affects over 15% of all individuals aged >60 years. In the elderly, systolic hypertension is a major modifiable cardiovascular risk factor. Systolic blood pressure (SBP) is associated with higher risk of an adverse outcome, whereas diastolic blood pressure (DBP) is inversely correlated with total mortality, independent of SBP, highlighting the role of pulse pressure as a risk factor. Three placebo-controlled outcome trials on antihypertensive drug treatment in older patients with isolated systolic hypertension have been published: the Systolic Hypertension in the Elderly Program (SHEP), the Systolic Hypertension in Europe (Syst-Eur) Trial and the Systolic Hypertension in China (Syst-China) Trial. These 3 trials demonstrated the benefit of antihypertensive drug treatment. A meta-analysis was performed by pooling the patients from these 3 trials with a subset of patients with isolated systolic hypertension from 5 other trials in the elderly. The pooled results of 15,693 older patients with isolated systolic hypertension prove that antihypertensive drug treatment isjustified if on repeated clinic measurements SBP is 160 mm Hg or higher.

Risk and benefit of treatment of isolated systolic hypertension in the elderly: evidence from the Systolic Hypertension in Europe Trial

The Syst-Eur trial investigated whether active treatment starting with the dihydropyridine calcium channel blocker (CCB) nitrendipine, could reduce the cardiovascular complications of isolated systolic hypertension (ISH) in the elderly. The intention-to-treat analysis showed that active treatment improved outcome. The per-protocol analysis largely confirmed these results. The effect of treatment on total and cardiovascular mortality might be attenuated in very old patients. Further analysis also suggested benefit in those patients who remained on nitrendipine monotherapy. Active treatment was more beneficial in patients with diabetes as compared with those without diabetes at entry and reduced the incidence of dementia by 50%. Analyses of data from the Ambulatory Blood Pressure Monitoring (ABPM) Side Project suggested that most of the benefit of treatment was seen in patients with a daytime systolic BP > or = 160 mm Hg. Finally, a meta-analysis partly based on Syst-Eur data showed that in older hypertensive patients pulse pressure and not mean pressure is the major determinant of cardiovascular risk.

The benefit of treating isolated systolic hypertension

Isolated systolic hypertension affects over 15% of all people older than 60 years of age. In the elderly, systolic hypertension is a major modifiable cardiovascular risk factor. Systolic blood pressure is associated with higher risk of an adverse outcome. Diastolic blood pressure is inversely correlated with total mortality, independent of systolic blood pressure, highlighting the role of pulse pressure as risk factor. Three placebo-controlled outcome trials on antihypertensive drug treatment in older patients with isolated systolic hypertension have been published: the Systolic Hypertension in the Elderly Program (SHEP), the Systolic Hypertension in Europe (Syst-Eur) Trial, and the Systolic Hypertension in China (Syst-China) Trial. These three trials showed the benefit of antihypertensive drug treatment. A meta-analysis was done by pooling the patients from these three trials with a subset of patients with isolated systolic hypertension from five other trials in the elderly. The pooled results of 15,693 older patients with isolated systolic hypertension prove that antihypertensive drug treatment is justified if systolic blood pressure on repeated clinic measurements is 160 mm Hg or higher.

Prevention of dementia in randomised double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) trial

BACKGROUND

Systolic hypertension increases the risk of dementia in elderly people. The vascular dementia project, set up in the framework of the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) trial, investigated whether antihypertensive drug treatment could reduce the incidence of dementia.

METHODS

Eligible patients had no dementia, were at least 60 years old, and had a blood pressure when seated of 160-219 mm Hg systolic and below 95 mm Hg diastolic. Active treatment consisted of nitrendipine (10-40 mg/day) with the possible addition of enalapril (5-20 mg/day), hydrochlorothiazide (12.5-25 mg/day), or both drugs, titrated or combined to reduce the systolic blood pressure by at least 20 mm Hg to reach a value below 150 mm Hg. Cognitive function was assessed by the mini mental state examination (MMSE). If the MMSE score was 23 or less, diagnostic tests for dementia were done (DSM-III-R criteria). The cause of dementia was established by the modified ischaemic score with brain imaging or the Hachinski score.

FINDINGS

Median follow-up by intention to treat was 2.0 years. Compared with placebo (n=1180), active treatment (n=1238) reduced the incidence of dementia by 50% from 7.7 to 3.8 cases per 1000 patient-years (21 vs 11 patients, p=0.05). The median MMSE score at randomisation was 29 in both treatment groups. At the last available assessment, systolic and diastolic blood pressure were, respectively, 8.3 mm Hg and 3.8 mm Hg lower (p<0.001) in the active-treatment group, but on average the MMSE scores did not change in either group. In the control patients, however, the MMSE decreased (p=0.04) with decreasing diastolic blood pressure, whereas in the active-treatment group MMSE scores improved slightly (p=0.01) with greater reduction in diastolic blood pressure (p=0.002 for between-group difference).

INTERPRETATION

In elderly people with isolated systolic hypertension, antihypertensive treatment was associated with a lower incidence of dementia. If 1000 hypertensive patients were treated with antihypertensive drugs for 5 years 19 cases of dementia might be prevented.

Clinical trials in cognitive impairment in the elderly

The pharmacological treatment of dementia is particularly difficult because of the uncertainty of the diagnosis and of the underlying pathogenetic processes, and because of the variable severity of the syndrome. This paper suggests several lines for future therapeutic trials in dementia. These include the need to work with homogenous populations and to take into account the natural history of the disease, the pharmacologic characteristics of the drugs, and the particular ethical considerations pertaining to demented patients. We review the diagnostic criteria for dementia, Alzheimer's disease (AD) and vascular dementia. We discuss the different types of therapeutic trial design, the problem of the duration of the protocol, the tools to evaluate the cognitive effects and the activities of daily living, and the use of a Clinical Global Impression of Change (CGIC). The results of some therapeutic trials in AD and vascular dementia are given as examples.