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Statins and stroke outcome

Study
Results
Comment

We know that statins reduce the rate of ischaemic stroke by about 25% or so, though probably not that of haemorrhagic stroke. A more difficult question is whether ischaemic strokes that occur with people taking statins are different in any way from those in people not taking statins. An observational study implies that there is at least the possibility that outcome after stroke is better in those who take statins [1].

Study

Consecutive patients admitted to the National Institutes of Health stroke programme in Maryland between mid-2000 and end-2002 were studied. There were 436 who had ischaemic stroke (not haemorrhagic stroke, or transient ischaemic attack), and who were aged 18 years or more.

On admission, risk factors for stroke were elicited from patient or family, as well as relevant medications (lipid lowering, anticoagulant, and antiplatelet drugs). Stroke severity was scored using standard scales, on admission and with the modified Rankin scale (see box) on admission and discharge.




Modified Rankin scale

  1. No symptoms at all
  2. No significant disability despite symptoms; able to carry out all usual duties and activities
  3. Slight disability; unable to carry out all previous activities, but able to look after own affairs without assistance
  4. Moderate disability; requiring some help, but able to walk without assistance
  5. Moderately severe disability; unable to walk without assistance and unable to attend to own bodily needs without assistance
  6. Severe disability; bedridden, incontinent and requiring constant nursing care and attention
  7. Dead



Results

Of the 436 patients with stroke, 95 had been taking statins before their stroke occurred. The average age was 75 years in both groups, with about half women. Stroke scores were similarly distributed in both groups, and 77% in each group had admission Rankin scores below 2.

Those on prior statins and those not on prior statins were comparable for most demographic features, risk factors, and laboratory values. Those on statins were more likely to have coronary artery disease (47% vs 17%) and hyperlipidaemia (80% vs 25%), and were more likely to use antiplatelet or anticoagulant drugs (66% vs 43%). LDL-cholesterol concentrations were significantly lower in those on statins.

Statin use in patients admitted with stroke increased over the period (Figure 1). Discharge Rankin scores were available in 393 patients. Scores of 2 or less (good outcome) at discharge occurred in 43/84 (51%) in patients taking statins, compared to 118/309 (38%) in those not on statins (Figure 2). Mortality was similar in both groups (Figure 2).



Figure 1: Statin use in patients admitted with stroke







Figure 2: Outcome and mortality by preadmission statin use





Factors associated with better outcome were lower admission stroke severity, lower white cell count, prior use of statins, and younger age.

Comment

No observational study provides certainty for a cause-effect relationship, unless a very considerable body of evidence can be built up, and the effect is large. One problem is that confounding may be going on because of factors whose importance we do not appreciate. Here, at least, patients in generally worse health before the stroke, and with a similar spectrum of severity of stroke, had a better outcome if they were taking a statin before they had their stroke.

Reference:

  1. SS Yoon et al. Rising statin use and effect on ischemic stroke outcome. BMC Medicine 2004 2:4 (www.biomedcentral.com/1741-7015/2/4)

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