Comparison of the EMTREE and MeSH indexing systems on their effectiveness to retrieve drug related information Informatio Medicata 2008, Budapest 25 September 2008 by Arthur Eger MSc, Account Development Manager

Aim of this study What are the differences between EMTREE and MeSH? How important are these differences when searching for drug related information? Why would you choose EMTREE or MeSH?

Methods As introduction a short synopsis of the EMBASE and Medline databases is given, followed by a comparison of the EMTREE and MeSH indexing systems to identify the advantages of each indexing system Experimental data is collected from several drug searches, both in EMBASE and MEDLINE/PubMed in which a term to term comparison for the 10 leading pharmaceutical products was performed The outcome of the searches was analysed to come to a conclusion

Introduction: EMBASE Biomedical database produced by Elsevier Comprehensive coverage of biomedicine with focus on drugs & pharmacology Indexed with EMTREE (with 55,666 Preferred Terms incl. 27,058 drugs and chemicals) Over 11 million records from 1974-present; currently covers 4,901 journals. Overlap with MEDLINE ca. 60% (at journal level) Unique records especially in drugs titles + European literature

Introduction: EMBASE.com 11 million EMBASE records AND 7 million Medline records (only unique Medline records added) Daily updates (more then 3,000 records added every working day) Linking retrieved articles to full text Combined drug and disease searches with easy to select biomedical limits and subheadings EMTREE facilitated searching

Introduction: Medline Biomedical database produced by NLM (U.S. National Library of Medicine) Focus on all of biomedicine incl. nursing, dentistry and veterinary science Indexed with MeSH (= Medical Subject Headings with 24,219 total Mesh Terms) 15 million records from 1966-present; currently covers 5,000 journals Overlap with EMBASE ca. 60% (at journal level) Unique records especially in US titles + nursing literature etc.

Comparing EMTREE and MeSH: what do they have in common? Biomedical / life science terminologies Similar facet structure (EMTREE was modelled on MeSH 18 years ago) Broader/narrower terms and synonyms Major annual updates with hundreds of new terms Links to CAS registry numbers and enzyme commission (EC) numbers

EMTREEMeSHImportance (for the user) “Natural language terminology” (e.g. myeloid leukemia) Has many “inverted terms” (e.g. leukemia, myeloid) Intuitive and recognisable terms for ease of use Has more than 225,829 synonyms (incl. almost 142,323 drug synonyms) Has far fewer synonyms (exact number unknown) High probability that term used by user is in EMTREE Includes all MeSH terms (many as synonyms) -EMTREE can easily be used by MeSH users Relies upon “meaning” invested in terms by authors using them Has many scope notes to describe how terms are usedNo dependence on or need to look up scope notes Larger (55,666 preferred terms)Smaller (24,219 preferred terms) Best chance of finding both drug and non-drug terminology Drugs facet has 27,058 preferred termsDrugs facet has only 2,711 termsDrugs terminology is better and more up-to-date New drug terms are updated earlier in EMTREE [1] [1] Drug terms are only updated when they become established Better results for new drugs Polyhierarchical structure with duplicated treesPolyhierarchical structure with differences between treesUnambiguous and context-free explosion searches Check tags and document types included within EMTREE Check tags and document types are in separate lists All the terminology you need is in one place (i.e. EMTREE) All drug and chemical information is included in EMTREE Detailed drug information is in a separate (“supplementary”) file All the drug information you need is in EMTREE Comparing EMTREE and Mesh: what are the differences?

MeSH advantages: Extensive history notes, which can be used to track earlier literature predating the introduction of particular terms. Extensive scope notes. Ad-hoc updates during the year (e.g. SARS in 2003). Extensive terminology in nursing, veterinary medicine and dentistry. EMTREE has a record of updating terminology in response to the needs of user groups in relevant areas such as pharmacoeconomics (1996), pharmaceutical vehicles and additives (1997), biotechnology (2001), alternatives to animal experimentation (2002) and nursing (2006).

EMTREE advantages: EMTREE drugs terminology is: – extensive, and supported by synonyms (including many trade names). – updated regularly and comprehensively, 746 drug preferred terms were added in – organized in a comprehensive tree structure, with drug terms structured from many points of view, including structure, activity, therapeutic use. – Useful in identifying, finding out about and searching new drugs.

Why consider EMTREE in drug searches? EMTREE terminology in general: – already includes all of MeSH (i.e. all MeSH terms are linked into EMTREE). – can be extended further in response to user needs, subject to agreement with overall policy. – Elsevier provides support to ensure that EMTREE is optimally embedded in user applications.

Experimental data collection Online study conducted 18th August 2008, on EMBASE.com and on Medline via PubMed. Drugs were top 10 leading products based on global pharmaceutical sales (source: Wood Mackenzie Top 100 Ethical Drugs by Sales ( r.com/ranking/ranking.html)). Search period: literature publication years

Experimental data collection Search method: A term to term comparison in which each database was searched for EMTREE as well as for MeSH preferred terms. Searched were: descriptors. For preferred terms that were not yet incorporated in the MeSH thesaurus, the Substance name, available from the MeSH Supplementary Concept Data was used instead. Where the Mesh term differs from the EMTREE term, the generic name was checked at official online sites for the drug and EMTREE was found to be correct according to these sites. The results are very different in EMBASE if you search for Omeprazole rather then Esomeprazole for example, there are 5,425 results for Omeprazole in EMBASE.

Experimental data collection Product name Preferred termCitations EMTREE MeSH or Substance name ² EMBASEMEDLINE LipitorAtorvastatin 7,6681,654 Advair Fluticasone propionate plus Salmeterol PlavixClopidogrel 9,5521,613 NexiumEsomeprazoleOmeprazole1,4931,558 NorvascAmlodipine besylateAmlodipine439621

Experimental data collection Product name Preferred termCitations EMTREE MeSH or Substance name ² EMBASEMEDLINE EnbrelEtanerceptTNFR-Fc fusion5,1971,375 ZyprexalOlanzapine 7,7751,498 RemicadeInfliximab 8,2232,461 DiovanValsartan 2, RisperdalRisperidone 7,9911,488

Discussion of the findings: Lipitor EMBASE found 7,668, MEDLINE found 1,654 between the years 2004 to 2008 Both appear to search the same term, and whereas EMBASE has unique pharmacological titles, this does not completely explain the larger number of records found in EMBASE compared to MEDLINE.

Discussion of the findings: Looking at Lipitor in EMTREE

The EMTREE preferred term is atorvastatin so this is term we use to search in EMBASE. The indexers will have used this term when indexing regardless of how the author referred to it.

Discussion of the findings: Looking at Lipitor in EMTREE We can see the many tree structures for lipitor based on therapeutic use for example.

Discussion of the findings: Looking at Lipitor in EMTREE Note the large number of synonyms. A search for atorvastatin will also search for all of the synonyms mentioned here.

Discussion of the findings: Looking at Lipitor in MeSH Compare this to a search in PubMed and you see that atorvastatin is NOT a MeSH heading, it is a substance name, you must use heptanoic acid or pyroles if you want to search a MeSH heading. The entry terms are the equivalent of synonyms but you see there are less then in EMTREE.

Discussion of the findings: Conclusion Atorvastatin is not a preferred term in MeSH and so it is not mapped in the same way as a preferred term A larger number of synonyms are included in the EMBASE search and so more records may be found This conclusion applies to many of the studied drugs in the table

Discussion of the findings: Looking at Nexium 1,493 records found in EMBASE and 1,558 records found in MEDLINE This time we find more results in MEDLINE, why?

Discussion of the findings: Looking at Nexium In EMTREE The EMTREE preferred term is esomeprazole so this is term we use to search in EMBASE. The indexers will have used this term when indexing regardless of how the author referred to it.

Discussion of the findings: Looking at Nexium In EMTREE We can see the many tree structures for esomeprazole based on therapeutic use for example.

Discussion of the findings: Looking at Nexium in MeSH Checking the generic term for Nexium on official sites finds it to be Esomeprazole. Here you can see that Omeprazole, as used in MEDLINE is an exploded term for protein pump inhibitor or pyridine derivative

Discussion of the findings: Omeprazole or esomeprazole? MeSH has chosen a term which is not used in official sites for nexium Omeprazole is an exploded term in the same tree structure as esomeprazole A search for omeprazole in EMBASE, gives very different results to a search for esomeprazole (5,425 results in EMBASE v.s 1,558 in Medline)

Summary of the findings Drug nameResults in EMBASEResults in Medline More found in EMBASE Found in EMBASE in % of total Lipitor7,6681,6546,01482% Advair % Plavix9,5521,6137,93986% Nexium1,4931, % Norvasc % Enbrel5,1971,3753,82279% Zyprexal7,7751,4986,27784% Remicade8,2232,4615,76277% Diovan2, ,21784% Risperdal7,9911,4886,50384% Total51,90212,81539,08780%

Conclusion Of the searched 10 product names, 80% of all retrieved records were retrieved in EMBASE In 2 occurrences more records were found in Medline (Nexium and Norvasc). The preferred term made the difference and here, it would appear that a search for the EMTREE preferred term gives you more accurate results. This example also applies to Norvasc

Acknowledgements The presenter would like to acknowledge the work of Mrs. Ann-Marie Roche Elsevier’s Pharma Development Group Senior Product Specialist, on preparing the searches and the basis of the slides shown in this presentation.