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Moving targets and a insufficient database search in a systematic review?
- Gunther Eysenbach (22 April 1999)
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Doctors' innumeracy needs tackling
- C Bell (6 May 1999)
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Gunther Eysenbach, Researcher University of Heidelberg, Dept. of Clinical Social Medicine
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The "systematic" review of Walton R et al. [1] appears to disregard a considerable body of knowledge, including controlled trials concerning insulin dosage recommendation systems [2-8], and illustrates the problems a systematic review may run into if the research question is not well enough defined in advance. First, the review states the aim to "identify all comparative studies in which computers were used to help determine the most appropriate drug dose" and in the original research protocol authors state to include all studies where participants are "patients receiving drug therapy based on advice from a computer" [9]. Thus, according to their own protocol, authors would clearly have to include studies where advice is given directly to patients or to nurses, such as in some software applications for diabetes management [2-8]. In the abstract of their review however, authors speak of "computers giving advice to clinicians" [1] (apparently excluding advice to patients and direct computer-assisted drug administration), but in the article body they broaden this concept again to include studies in which computers administer drugs directly to the patient (but inconsequentially not to those where drug advice is given to the patient). One would at least have expected some discussion for the reason to exclude studies where advice is given to the patient, especially in the light of the fact that insulin treatment in diabetes (having clear physiological parameters) should be a very nice model to demonstrate the power of computerised drug advice and also because contamination effects (the administering clinician treating both patients from control and intervention groups learns from the computer advice of the intervention group) cannot occur in these studies. Secondly, the authors used an insufficient search strategy, which may have led to non-retrieval of studies (e.g [10]) and potential bias. The use of "prescr*" as a search term for the broad concept of drugs (including medication administered by computer-controlled infusion pumps) is a major flaw, leading to non-retrieval of at least 261200 MEDLINE articles which deal with pharmaceutical preparations but do not use the word stem "prescr*". Equally insensitive is the usage of the search term comput*, (for example, at least 9967 MEDLINE articles use the word "software" or "expert system" without using " comput*"). To rely on the MeSH term "Computer-Assisted Decision Making" alone (which was introduced as late as 1987) is a rather insensitive approach for this broad research question, again especially in the context of computer-controlled pumps. Thirdly, the authors claimed to include other research designs such as interrupted time series, but confusingly this is not reflected in the search strategy "randomised controlled trial OR random allocation OR double blind method", which appears to target primarily randomised controlled trials. In summary, the authors seem to have pursued a moving target, originally having in mind computerised advice to improve "prescribing practice" (as reflected in the title of the original research protocol [9]) and subsequently broadening this concept to computer support for determining drug dose including computer-controlled pumps (which is a much broader and different concept). Their aim of this review was to determine "whether there is clear evidence that computerised advice on drug dosage is beneficial"[9], therefore evidence regarding computer-advice given directly to patients should have been included in this review (even if this group of studies would perhaps have required subgroup analysis). These problems should illustrate the importance of defining a clear search strategy in advance (which has not been done in the protocol of this particular systematic review [9]) and the importance of consulting an experienced information broker before conducting a literature search.
Dr Gunther Eysenbach Researcher, Cochrane Skin Group University of Heidelberg Email: ey@yi.com
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C Bell
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Editor Walton and colleagues (BMJ 10 April, 1999, pp 984-90) conclude that wider use of computers in hospital practice would help determine optimal drug doses more effectively. There is no doubt that this is true and, in situations where complicated pharmacokinetics are involved, there is also no realistic alternative. However, there is the additional issue, alluded to in the introduction of Walton et al's paper, of the appalling lack of basic numeracy in our current graduates. Walton et al cite Rolfe and Harper's frightening finding in 1995 that over 50% of hospital doctors were not able to convert a percentage solution into a concentration. One of my teaching colleagues last week drew my attention to the fact that some of our students cannot identify which are centimetre and which are inch graduations on a ruler. This is so basic a problem that it cannot be ignored, especially at a time when so much attention is being paid to restructuring of medical education to meet contemporary needs. Since the schools system is apparently no longer able to ensure numerate competency, we need to devise some other strategy to guarantee it. Perhaps it should represent one of the mandatory clinical skills; perhaps our colleagues with problem-based courses could look to giving this aspect of problem-solving as strong an emphasis as the abilities to communicate and to use a library. Professor C Bell Head, Dept of Physiology Director of Preclinical Studies, School of Medicine Trinity College Dublin Dublin 2, Ireland |
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