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DynaMed can be assessed at
  1. Oxford, UK

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    DynaMed, a medical information website, aims to provide information for health professionals at the point of care. Though it’s a subscription (US $200/y) only site (with a 30 day free trial), users have the option to earn free access by authoring or reviewing a topic. DynaMed receives no commercial funding.

    The 1800 clinical topic summaries include most diseases we looked for, but little information was provided on clinical presentations. For example, we found nothing on ankle swelling or itch. Summaries are written by experienced clinicians, usually family practitioners, but currently only 10% of the summaries have been peer reviewed. Authors are encouraged to use best evidence sources (eg. Cochrane, systematic reviews, and meta-analyses) as first line, followed by textbooks and guidelines, and finally, primary evidence. In March 2004, DynaMed adopted grading of evidence with recommendations graded on the basis of the evidence supporting them. Most topics we looked at included at least some high quality evidence, but few specified the grade of the evidence.

    The summaries are organised alphabetically and by category. The alphabetical list is long but easy to use; the category headings are less easy. The categorisations by specialty are useful, but others are less so. For example, the category “Common healthcare topics” comprises 9 random articles. Some categories that might be expected are absent (eg, ear, nose, and throat).

    All topic summaries are accessible under a series of collapsible menus: description, causes and risk factors, complications and associated conditions, history, physical, diagnosis, prognosis, treatment, prevention and screening, references, and patient information. Most summaries are comprehensive and fairly easy to navigate, with information in bullet point format, and they include both textbook information and current thinking. I thought some summaries contained too much information for point of care use, with a tendency to quote lots of different studies rather than summarise the information and produce a bottom line. Helpfully the majority of the references are hyperlinked to either the full text article or the PubMed abstract. There are also links to other DynaMed articles.

    Many of the topics contain links to patient information leaflets, but these are of variable quality. We did not find DynaMed criteria for leaflet selection. Summaries are continually updated following systematic surveillance of current literature, but many summaries do not state the date of writing, who the author was, or when future review is scheduled for.

    The site has an extensive selection of links, many of which are well respected evidence-based sites. For the rest, there is no comment on the standards of their information, but on the whole they seemed good.

    DynaMed is an American website, which limits some of its usefulness. For example, drug names are American, as is information such as immunisation schedules and guidance on investigation and referral. I found the most significant limitation to be the absence of any reference to British guidelines (eg, NICE and SIGN).

    Basic and advanced searches are available. Neither is fantastic; we searched for proteinuria, which got 82 hits with no way of reducing it. Results were not in order of relevance as proteinuria was eighth with cadmium poisoning first. Only US spellings are recognised, so diarrhoea returns nothing.

    In summary, it may take time to find the article that you want, particularly if you need to use the search engine. Once found, the material is usually comprehensive and attempts with some success to be both evidence-based and practical. The site is likely to be most useful to general practitioners who know what the diagnosis is and want more information; it is less useful if you don’t have a diagnosis. I think I will be keeping my $200 (but I’d use it if it was free!).


    Methods and quality ★★★½☆

    Usefulness ★★½☆☆

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