Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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![[Read Rapid Response]](/icons/misc/sectionDOWN.gif)
Does it help to use the best search strategy?
- Jos H Verbeek, Jos Verbeek, Jukka Salmi (14 April 2004)
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Network of expertise
- Sara J Stock (30 April 2004)
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New search filter for diagnostic studies: Ovid and PubMed versions not the same
- Yngve T Falck-Ytter, Edith Motschall, Library services manager, Institute for Medical Biometry and Medical Informatics, University Hospital Freiburg, Germany (28 May 2004)
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Response to letter: New search filter for diagnostic studies: Ovid and PubMed versions not the same
- Nancy L Wilczynski, R. Brian Haynes (25 January 2006)
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Response to letter: Does it help to use the best search strategy?
- Nancy L. Wilczynski, R. Brian Haynes (3 February 2006)
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Response to letter: Network of expertise
- Nancy L. Wilczynski, R. Brian Haynes (3 February 2006)
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Jos H Verbeek, coordinator occupational health field Finnish Institute of Occupational Health, Kuopio, Finland, Jos Verbeek, Jukka Salmi
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Dear Dr Haynes and Dr Wilczynski, We are very happy with your work on search strategies, because it helps us to spend our time on searching more efficiently. At the moment, we are studying on an optimal search strategy for occupational health intervention studies. Therefore, we read your article with more than ususal interest. Although the message from the article was clear, we were still confused about how we could best use the search strategies that you found to be the most optimal. We used the example from your article on arthritis to find the meaning of the search strategies in practice. You found 3451 articles with 'diagnosis' AND 'arthritis', which motivated you to find better strategies. Using your best search strategy with highest specificity and accuracy '(specificity.tw)' in PubMed, we found 3210 articles. Not a very spectacular improvement. When we use the PubMed filter 'specificity[tiab]' from the Clinical Queries box, the number of articles decreases to 1475. That seems to be more helpful for a busy clinician, but still far too many articles to handle in a couple of minutes. In addition, it is confusing that this is a different search term than the one that you propose in your latest article. Combining more of the advocated best search strategies reduces the number of articles to a number that is better to manage in a short time, apparently also with increasing the specificity. For the busy clinician, it would be helpful to know the implications of using such a strategy. We feel that it would increase the possibilities for implementation of your work in practice if you could shed some light on this problem. Competing interests: None declared |
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Sara J Stock, Library Services Manager Colchester General Hosptial, Essex, CO4 5JL
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I agree with Prof Haynes and his colleague that clinicians lack the time to search the literature and often fail to search effectively. However, they have not mentioned one of the obvious solutions to these problems. Hospitals in the UK and elsewhere have libraries and librarians. Librarians have the expertise and experience to enable them to search effectively on clinicians' behalf. The practice of medicine and healthcare requires team work. Every clinician relies on a network of colleagues from other professions and specialities to complete the picture of patient care. The wise clinician looks upon colleagues in the library as another essential part of that network of expertise. Competing interests: None declared |
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Yngve T Falck-Ytter, Associate Director German Cochrane Centre, 79104 Freiburg, Germany, Edith Motschall, Library services manager, Institute for Medical Biometry and Medical Informatics, University Hospital Freiburg, Germany
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Dear Dr. Haynes, We read with great interest your article about your new search strategy to identify diagnostic accuracy studies. Since its implementation at PubMed as a search filter within clinical queries, it has been a great service to everybody with an interest in evidence-based medicine. However, when running the sensitive version of the strategy within PubMed, we noticed differences from the version published in BMJ (Ovid version). We are wondering whether a slightly modified version would be even better in both systems. Here is what we think: your new sensitive search filter (sensitiv:.mp. OR diagnos:.mp. OR di.fs.) is straight forward in Ovid, but because of the tag ".mp.", it is not easily portable to PubMed. For example, "diagnos:.mp." has been translated into an array of terms including the search term "diagnostic * [MeSH:noexp]". However, running this term does not perform as one would expect: only 4 instead of the possible 18 MeSH headings are found and it appears that this PubMed syntax is unable to identify MeSH headings that include a comma or an "and", i.e. "diagnostic techniques, cardiovascular" or "diagnostic techniques and procedures". But your original Ovid notation actually finds all these MeSHs resulting in a different cover range than the PubMed version. Conversely, the search "sensitivity and specificity[MeSH Terms]" as part of the translated version in PubMed includes the important terms "predictive value of tests" and "ROC curve". However, it does not look like these terms are actually included in your published strategy (sensitiv:.mp. OR diagnos:.mp. OR di.fs.), since "sensitiv:.mp." will not be able to pick them up. Maybe adding these terms would actually increase the accuracy of the search? We, therefore, performed the following tests (details not shown) to analyze whether a more congruent version between Ovid and PubMed is possible. First, we did a "back translation" of the PubMed strategy into Ovid syntax and compared the resulting two versions within Ovid. Then we constructed a PubMed compatible version with Ovid syntax within Ovid. Finally, we took the best of both worlds (Ovid and PubMed, that is) to construct a version that may potentially improve overall accuracy. So, based on your work (and without going into lengthy details), the following is a slightly modified version that we would suggest as a potential alternative: For PubMed: sensitiv*[Title/Abstract] OR sensitivity and specificity[MeSH Terms] OR diagnos*[tw] For Ovid: sensitiv:.tw. or exp "sensitivity and specificity"/ or diagnos:.tw,ot,hw,rw. or (di or du).fs. We would be very curious (and extremely thankful) to hear whether these alternate strategies may in fact perform more accurately when tested on your reference set. With kind regards, Yngve Falck-Ytter, M.D. and Edith Motschall Competing interests: None declared |
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Nancy L Wilczynski, Doctoral candidate McMaster University, R. Brian Haynes
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Dear Dr Falck-Ytter and Edith Motschall, Thank you for your letter regarding our search strategies for detecting diagnostic studies in MEDLINE. As indicated by Dr. Falck-Ytter and Edith Motschall (F-Y M) there is no direct translation of Ovid terms tagged with “.mp.” to PubMed. In translating our Ovid strategies to PubMed syntax we worked with the National Library of Medicine and display on the Clinical Queries screen the best possible translations currently available. Prior to developing our search strategies, we compiled a list of 4,862 unique terms which were derived by consulting numerous sources as outlined in the paper. The list of terms is not exhaustive and thus there are many additional ways to search MEDLINE using a number of tags available through Ovid (e.g., .ot., .hw.). All methods of term searching were not tested in our database. However, we did test over 17,000 search strategies for detecting diagnostic studies. Although we are currently unable to test the F-Y M strategy proposed for Ovid in our database we are able to conduct a test to compare retrieval. We tested the F-Y M Ovid search strategy “AND”ing it to the MeSH Term "Altitude Sickness" for a disease concept and limited the search to the publishing year 2002. (This tactic makes the search yield tractable for comparisons.) This search yielded 37 citations. We did the same for our most sensitive diagnosis search strategy, yielding 34 citations, all of which were picked up by the F-Y M proposed Ovid strategy. Thus, the F-Y M strategy picked up three additional citations. Our most sensitive strategy correctly eliminated these three citations as one would be classified as etiology, one would be classified as “something else”, and one does not pass the methods filter for diagnosis. Additionally, we ran the F-Y M PubMed translation and our PubMed translation in PubMed using the MeSH Term "Altitude Sickness" for a disease concept and limited the search to the publishing year 2002. Both searches yielded the same 40 citations, including all 37 from the F-Y M Ovid strategy with three additional citations; all 34 from our Ovid retrieval with six additional citations. From this test it appears that the PubMed strategy purposed by Falck- Ytter and Motschall performs much the same as the one posted on the Clinical Queries page of PubMed and that the proposed Ovid strategy picks up more false positives than our strategy posted on the Ovid “Limits” page resulting in lower precision. Best regards, Nancy Wilczynski, MSc and Brian Haynes, MD, PhD Competing interests: None declared |
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Nancy L. Wilczynski, Doctoral candidate McMaster University, R. Brian Haynes
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Dear Dr. Verbeek and Dr. Salmi, We thank Drs. Verbeek and Salmi for their letter. Drs. Verbeek and Salmi tested in PubMed our highly specific strategy (‘specificity.tw.’) reported in our paper, and then tested our highly specific strategy (‘specificty[tiab]’) as displayed on the Clinical Queries screen of PubMed. Please note, that the search strategies reported in our article are in OVID syntax. Our strategies have been translated for use in PubMed and can be utilized through the Clinical Queries screen of PubMed. When searching in Ovid you should use the search strategies as reported in the paper (i.e., ‘specificity.tw’) and when searching in PubMed you should use the search strategies reported on the Clinical Queries page. In the example Drs. Verbeek and Salmi describe, the PubMed equivalent of Ovid’s ‘.tw.’ is ‘[tiab]’ not ‘[text word]’ (which would yield a much larger retrieval). The narrower yield that results from using our search strategy is achieved because the search strategy filters out diagnosis articles that are not methodologically sound, and looks for “specificity” in the title and abstract only rather than searching anywhere in the article. As Drs. Verbeek and Salim note, the most specific strategy still retrieved too many articles to handle in a couple of minutes. It is important to note, however, that the retrieval has been significantly reduced compared with the retrieval when searching without this filter. When developing the most specific search strategy to identify scientifically sound, clinically relevant diagnosis articles in MEDLINE, we tested up to three ‘ORed’ search terms (both MeSH and textwords) and found that the single term ‘specificity.tw.’ (Ovid syntax) yielded the highest specificity at 98%. Thus, we are not sure how Drs. Verbeek and Salim combined strategies to increase the specificity. It would be desirable to have strategies that perform better than those that have been developed. In our soon to be published work, we add age- specific search strategies to our current search filters for MEDLINE, to further narrow the search. Clinicians searching for a diagnosis article will likely be best served by the most specific search strategy. The overall yield will be reduced by the content term(s) used. The retrieval may still be substantive but it is significantly reduced from when searching without the filter while carrying the guarantee that scientifically sound studies will be included. Best regards, Nancy L. Wilczynski, MSc and R. Brian Haynes, MD, PhD Competing interests: None declared |
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Nancy L. Wilczynski, Doctoral candidate McMaster University, R. Brian Haynes
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Dear Sara Stock, We agree that a network of health care professionals are important in distributing information to a busy physician, and we certainly support the vital role that librarians play in assisting clinicians with their searching needs. Unfortunately, there are not enough librarians to deal with all clinical queries, especially during off-hours. Our search strategies are presented as an option for clinicians who wish to or have no other option but to perform a search on their own. Additionally, they are presented as an option for clinicians who lack critical appraisal skills as these strategies will help filter out studies that are not scientifically sound. We hope that they are also useful for librarians. Best regards, Nancy L. Wilczynski, MSc and R. Brian Haynes, MD, PhD Competing interests: None declared |
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