Rehabilitation Of The Older A... Health Article

Stroke Risk Factors

The outcome of a patient with a treated stroke may never be as good as that of someone in whom a stroke is prevented [5]. The identification and modification of risk factors should begin as a primary prevention measure and continue after a stroke as a secondary prevention measure during the acute care and rehabilitation phase. There are specific and well-defined risk factors for stroke, both modifiable and unmodifiable, that are well-known to most clinicians. Advanced age, hypertension, atrial fibrillation, statin use, and alcohol consumption are discussed in terms of their impact on the elderly.

Age is the most important unmodifiable risk factor for all stroke types including ischemic stroke. For each successive 10 years after the age 55, the stroke rate more than doubles in both men and women [6,7]. Approximately 65% of all strokes occur in those who are over the age of 65. Data from Rochester, Minnesota, demonstrated that more than half of the strokes in this population affected subjects aged >75 years and nearly one quarter affected subjects aged >85 years. Furthermore, elderly stroke patients are reported to have more severe strokes, higher case-fatality rates, and larger proportion discharged to long-term institutional care. In general, the frequency of stroke is higher in males than females until the age of 55. After the age of 55, the risk is nearly equal for both men and women. Because women tend to live longer than men, however, more women die of stroke each year.

Hypertension is considered the most important modifiable risk factor. The efficacy of antihypertensive treatment in preventing stroke is well established in all age groups. Using blood pressure of over 140/90 mm Hg to define hypertension, about 20% of the adult population has hypertension, whereas for people over the age of 65 years the prevalence is as high as 65% [8]. Since 1991, the results of three major trials (the British Medical Research Council trial of treatment in older adults, the Swedish Trial in Old Patients with Hypertension, and the Systolic Hypertension in the Elderly Program) have conclusively established the benefits of treating older patients (>60 years) with both diastolic and isolated systolic hypertension. International guidelines for the management of hypertension (including the Fifth Report of the Joint National Committee, the 1993 report of the World Health Organization and the International Society of Hypertension, and the second report of the British Hypertension Society Working Party) have all been modified to reflect the emerging evidence concerning the benefits of treating older patients. Cost-effectiveness data are similarly in accord with giving high priority to the treatment of older individuals with hypertension.

Atrial fibrillation is an important cardiac risk factor in the elderly and is estimated to cause almost half of all cardioembolic strokes. The prevalence of atrial fibrillation in people over 60 is approximately 5% and rises to almost 15% after the age of 75. Studies have shown that stroke patients with atrial fibrillation are significantly more likely to be dead, disabled, or handicapped at 3 months than those without atrial fibrillation [9]. There is an increased risk of subsequent stroke in the elderly patient with atrial fibrillation, yet many are not being treated. Although warfarin therapy with international normalized ratio between 2 and 3 dramatically reduces the risk of stroke, the risk of intracranial hemorrhage is increased in patients older than 75 years and in those anticoagulated with an international normalized ratio above 3. The decision to treat with warfarin therapy should be made by weighing the benefits against the risks for that individual.

There is compelling evidence that 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins) are strongly associated with lower risk of coronary disease. In the Prospective Study of Pravastatin in the Elderly at Risk trial, pravastatin was shown to reduce the risk of coronary events in elderly people with a history or risk of vascular disease [10]. Until recently, data regarding the specific relationship between hypercholesterolemia and stroke were less robust. According to data from the Heart Protection Study, there was an overall 25% reduction of first event rate for stroke. Among patients with pre-existing cerebrovascular disease there was no apparent reduction in the stroke rate, but there was a significant reduction in the rate of any major vascular event [11,12]. The association between plasma cholesterol levels and risk of stroke seems to diminish with increased age [13]. Statins have shown worsening of cognitive function in two randomized trials [14,15] and several case reports [16–18]. The Heart Protection Study and Prospective Study of Pravastatin in the Elderly at Risk trial, however, did not show favorable or deleterious effects on cognitive measures that were tested. There is still controversy over the finding that statins increased the frequency of new cancer diagnoses in elderly individuals [10] , although recent experience in long-term trials allay concerns that there was a cause and effect relationship. Although there are clear benefits of statin therapy after a stroke, the potential side effects should be considered in the elderly.

There is a variable association between alcohol consumption and stroke. Alcohol has been reported to be a possible risk factor for thromboembolic stroke [19] , and as a protective factor for stroke with light or moderate consumers [20,21]. Moderate consumption of alcohol (one to two drinks per day) may reduce cardiovascular disease including ischemic stroke; however, there seems to be a dose-response relationship between moderate consumption and the risk of intracerebral and subarachnoid hemorrhage. There is only limited evidence that moderate amount of drinking may have a protective effect among those older than 65 [22]. Alcohol should not be considered as a preventive agent for stroke. There are serious concerns of alcohol use in the elderly including alcohol-medication interactions, acceleration of age-related postural instability, and increase in falls [23]. It is recommended that the elderly abstain from alcohol use.