Hi, Would someone like to answer this question. Thanks, Olive Olive Goddard Centre and Editorial Manager Centre for Evidence-Based Medicine Room 4 Oxford University Department of Psychiatry Warneford Hospital, Headington Oxford, OX3 7JX ..................................................................... Tel: +44 (0)1865 226485 email: [log in to unmask] Fax: +44 (0)1865 793101 web: www.cebm.net Mobile: 0773 484 2403 web: www.cebmh.com