Lancet
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The enthusiasm for meta-analyses (or overviews) expressed by their proponents is not always shared by the broader medical community. To encourage constructive debate, we adopt a critical perspective on the conduct and interpretation of meta-analysis. ⋯ We conclude that meta-analysis is not an exact statistical science that provides definitive simple answers to complex clinical problems. It is more appropriately viewed as a valuable objective descriptive technique, which often furnishes clear qualitative conclusions about broad treatment policies, but whose quantitative results have to be interpreted cautiously.
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Comparative Study
Outcome in patients with subarachnoid haemorrhage and negative angiography according to pattern of haemorrhage on computed tomography.
15% of patients with spontaneous subarachnoid haemorrhage have normal cerebral angiograms; they fare better than patients with demonstrated aneurysms, though rebleeding and cerebral ischaemia can still occur. In patients with a normal angiogram and accumulation of blood in the cisterns around the midbrain--"perimesencephalic nonaneurysmal haemorrhage"--outcome is excellent. To test the hypothesis that rebleeding and disability in angiogram-negative subarachnoid haemorrhage might be limited to those with other patterns of haemorrhage on initial computed tomography (CT), complications and long-term outcome were studied in 113 patients with angiogram-negative subarachnoid haemorrhage, admitted between January, 1983, and July, 1990. ⋯ Patients with a perimesencephalic pattern of haemorrhage have an excellent prognosis. Rebleeding, cerebral ischaemia, and residual disability occur exclusively in patients with aneurysmal patterns of haemorrhage on initial CT. Repeated angiography in search of an occult aneurysm is justified only in the patients with aneurysmal patterns.
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The dietary factors believed to be linked with the incidence of coronary heart disease are reviewed in the light of evidence with regard to their functional role, either in protection or in promotion. Detailed analysis of the evidence shows that the relations are more complex than the current lipid hypothesis suggests. It is proposed that, in particular, the polyunsaturated/saturated ratio as a measure of the propensity of the diet to influence the incidence of coronary heart disease should be replaced by indices of atherogenicity and thrombogenicity.