Poststroke prevention strategies cut dementia risk in half



LONDON – Cognitive dysfunction following a stroke could be reduced significantly if treatment with antihypertensive, antithrombotic, and lipid-lowering drugs were optimized, according to a study looking at the long-term impact of secondary prevention strategies.

The relative risk for cognitive dysfunction was 0.8 with the optimal use of anticoagulants, and 0.9, 0.9, and 0.9 with the optimal use of dual antihypertensive therapy, dual antiplatelet therapy, and lipid-lowering treatment, respectively.

"The combination of antihypertensives, antithrombotics, and lipid-lowering drugs reduced the risk of cognitive impairment by about half," Abdel Douiri, Ph.D., said at the annual European Stroke Conference. The benefit was seen in most stroke subtypes, although not in those with hemorrhagic stroke or in patients with stroke due to atrial fibrillation.

Dr. Douri of King’s College London and coinvestigators looked at whether preventing vascular events could be associated with a protective effect on patients’ overall cognitive function after a stroke. They used the population-based South London Stroke Register to identify 4,413 patients who had experienced a first stroke between 1995 and 2011. Patients were assessed for cognitive function using the Abbreviated Mental Test or Mini-Mental State Examination at about 3 months after their stroke and annually thereafter.

The mean age of patients was 70 years, 49% of the cohort were female, and 70.5% were white. Blacks (21.2%) and other ethnicities made up the remainder of the patient population.

Cognitive impairment rates after stroke vary by study, but have been shown to be relatively consistent over time, affecting up to a quarter of patients overall, Dr. Douri noted (Stroke 2013;44:138-45). Approximately 10% of stroke patients have cognitive impairment prior to their first stroke, 10% develop dementia after a single stroke, and 30% develop dementia after recurrent strokes (Lancet Neurol. 2009;8:1006-18).

Current treatment strategies for preventing cognitive impairment after stroke tend to focus on reducing the risk of recurrent stroke or other vascular events, although most studies to date have had short follow-up or too few patients, with only a small number of these having vascular causes for their cognitive problems.

"The use of recommended therapies after stroke appears to be associated with a protective effect," said Dr. Douiri.

Suboptimal lipid-lowering post stroke

Although optimizing poststroke medications might improve cognitive outcomes, it is not always achieved in routine care. The results of a separate prospective population-based study showed that lipid-lowering targets are not always being achieved.

"The suboptimal lipid control we observed, both preceding and following a stroke or TIA [transient ischemic attack], even where there was established vascular disease or risk factors, highlights the need for improved lipid management in patients who are at risk of stroke or TIA," said Dr. Danielle Ní Chróinín of Mater University Hospital and University College Dublin.

Dr. Chróinín and colleagues assessed patients’ lipid profiles and clinicians’ adherence to evidence-based guidelines for lipid-lowering medications after a stroke or transient ischemic attack using data from the North Dublin Population Stroke Study.

Over the course of the 1-year study, the medical records of 428 patients who had had an ischemic stroke and 188 who had had a TIA were analyzed. The mean age of patients was 71 years.

Lipid measurement at presentation and prescription of statin therapy at discharge were found to be less likely in female patients, those who were older, those with poorer modified Rankin scores before the event, and those with higher National Institutes of Health Stroke Scale scores. There was no difference in the likelihood of measurement or statin treatment based on the type of event or if the patient required hospitalization.

At presentation, only 33.7% of high-risk patients were being treated with lipid-lowering medications. Although 75.5% of patients were discharged on statin therapy, approximately one in four patients who should have been prescribed this medication were not taking a statin at discharge.

Of patients who were on lipid-lowering therapy, less than half (44%-46%) were achieving recommended target levels set by U.S. or European guidelines.

Statin treatment at discharge was more likely in patients who had concomitant diabetes or atherothrombotic stroke.

The study presented by Dr. Chróinín was supported by the Health Research Board, the Irish Heart Foundation, and a Mater University postgraduate research and education grant. Dr. Chróinín and Dr. Douiri said they had no relevant financial disclosures.

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