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A good summary of the literature on this frequently asked question. Some
excellent tables and a useful citation listing. The important take home message is sadly all too familiar: inadequate studies to allow an evidence
based reccommendation, bigger studies needed, etc.! In otherwords, no ‘evidence based’ reason need to change your current practice, whatever it
may be, but plenty of good reasons to think about modifying it.

– Monty Mythen