Journal of Human Nutrition and Dietetics (1999), 12, 237–244 Why appraise the evidence? a case study of vitamin C and the healing of pressure sores G. North* and A. Booth† *Community Dietitian, Chesterfield Royal Hospital (NHS) Trust; and †Director of Information Resources, School of Health and Related Research (ScHARR), University of Sheffield Background: The adoption of ‘evidence-based healthcare’ requires that practitioners can identify and interpret findings from rigorous research with a view to introducing them into clinical practice. This, in turn, necessitates the prior acquisition of skills in information retrieval and critical appraisal. Aim: To examine how the systematic retrieval and subsequent appraisal of research might usefully inform clinical practice. Method: A community dietitian investigated the effect of vitamin C on the healing of pressure sores using skills acquired from a course on systematic reviews and critical appraisal. Results: A systematic search across a range of databases identified two randomized controlled trials which were critically appraised and a critical commentary produced. Conclusion: There is insubstantial evidence to support use of a daily vitamin C supplement for healing pressure sores. Over 20 years’ treatment of pressure sores has been found to be based on a single flawed study. Key words: ascorbic acid, critical appraisal, decubitus ulcers, evidence-based healthcare, information retrieval, wound healing. Introduction a review thus: ‘A systematic review is the process of systematically locating, appraising and synthesising evidence from scientific The current emphasis within the National studies in order to obtain a reliable overview’ Health Service on clinical effectiveness places (Droogan & Song, 1996). Implementation of the a requirement for practice which is based on NHS Research and Development Strategy has the findings of rigorously conducted research. therefore involved the commissioning of a One way of providing access to such research number of such systematic reviews targeted in an easily assimilable form is through the at specific healthcare issues. Typically, such production of a systematic review. The NHS reviews take between 6 months and 1 year to Centre for Reviews and Dissemination, based complete and cost between £20 000 and at the University of York, characterizes such £50 000 to conduct. Obviously, practitioners who are delivering direct patient care rarely have the time, Correspondence: Andrew Booth, School of resources and skills to gather together research Health and Related Research (ScHARR), evidence and subject it to critical appraisal to University of Sheffield, Regent Court, 30 Regent the degree outlined above. Nevertheless, the Street, Sheffield S1 4DA, UK. Tel: +44 same principles and methods are applicable (0)114 2225420; fax: +44 (0)114 2724095; e-mail: A.Booth@sheffield.ac.uk to less rigorous, but no less important,  1999 Blackwell Science Ltd 237