Latest revision as of 13:49, 24 January 2017

About LILACS

Health sciences in Latin America and the Caribbean, even if does not experience the same degree of development as in the U.S. or Europe, maintain an activity that has generated a considerable literature nucleus. However, it is common for journals of the region published by scientific and professional societies as well as research institutes to have economic problems affecting the regularity and continuity of the appearance of their journals. A direct consequence of this problem is reflected in the low representation in international databases and repertoires. Despite the significant expansion MedLine has been maintaining for some years, the inclusion of Latin American biomedical literature has always been scarce and, in some countries’ cases, inexistent.

LILACS, Latin American and Caribbean Health Sciences Literature is a PAHO venture made to address the lack of coverage in large databases of the region’s relevant journals and also to generate visibility to the scientific activity that was going unnoticed. While working with a much smaller universe of literature, it has the ability to be quite comprehensive in its mission and provide the point of view of authors whose scenario is much more like ours than the U.S.’ or Europe’s.

LILACS is part of the VHL’s collection!

A LILACS’ characteristic is that it is not limited to journal articles indexing; it also includes theses, books, official documents, book chapters and factual information and statistics from international organizations regarding the region, such as PAHO.

Taking Medline as a model, LILACS also offers a variety of access points to information, allows the use of complex search strategies, and also has a controlled vocabulary based on MeSH (Medical Subjects Heading), which is called DeCS.

LILACS – Literatura Latinoamericana y del Caribe en Ciencias de la Salud (Latin-American and Caribbean Health Sciences Literature)

The platform for the Virtual Library of Health or VHL (which contains several information sources besides LILACS) was developed by BIREME - an information center maintained jointly by PAHO and the Government of Brazil - in the three predominant languages in the region: Spanish, Portuguese and English.

Like PubMed, VHL also unifies the contents of more specific databases (BBO for dentistry; BDENF for nursing; DESASTRES for emergency situations, and many more) and international databases (Medline and Cochrane Library)

Search in LILACS

The main difference between VHL and PubMed (and between LILACS and MedLINE in PubMed) is the search engine.

Through the LILACS Homepage - [1] – we can access two search interfaces:

• IAHx Search Interface – The default, it groups the search results into “clusters”
• IAH Search Interface – ISIS based, via form and index browsing

Both interfaces allow us to combine main LILACS search fields, but in different ways. The IAHx interface is the newest and is available in the LILACS homepage by default. The IAH will be discontinued once the IAHx advanced interface is available.

Fig.2 LILACS Homepage – the search interface by default is called IAHx Interface. The link to IAH Interface is available yet

Fig. 3 – IAH Search Interface – search via form, combining up to 3 search criteria

As in any database, LILACS provides access to information by author, article title, descriptors (DeCS), abstract, language, country of origin, year of publication, etc..

This information is organized into data fields that can be selected via a menu or indicated by the field tag, and can also be combined with other terms using Boolean operators with other terms.

LILACS Search Fields

The two LILACS search interfaces offer access to the data fields via a drop down menu or by entering a field tag prefix, which can be combined using Boolean operators with other terms of the same field or another one. If no field tag prefix is introduced the search will be done as if you introduce Text Words (TW).

Main Search Fields – LILACS

The search field can be selected via a menu or indicated by the field tag prefix, and can also be combined using Boolean operators with other terms. Let demonstrate how to use the search fields in LILACS stating by the LILACS default search interface – IAHx.

Fig.5 - Search using the field tag (colon : before the word or phrase) - Interface IAHx

Fig.6 - Search for phrase between double quotes " " in the selected field Title - Interface IAHx Note: It results the same if using the field tag TI: before the phrase – e,j, TI:"stent thrombosis"

In the IAH search interface we can do same searches but in different way.

Fig. 7 – Drop Down menu of search fields - Interface IAH Note: The menu includes all data fields available for search in LILACS

Fig.8- Search for two words using Boolean operator - IAH interface Note: In some fields, this interface does not search by phrase (See Table - LILACS Main Search Fields)

Viewing LILACS Records - citations

The display of LILACS’ records reflects nearly the same information as displayed by PubMed "Summary" format, including, if available, the link to the electronic journal and full text of articles or documents.

Fig.9 – Presentation of search results - Interface IAHx

The short format is default in iAHx Interface. To view the records in full format, switch to the detailed format.

Fig.10 – Example of LILACS citation for Journal article in detailed format - Interface IAHx

Fig. 11 - Example of LILACS citation for Journal article in detailed format - IAH interface.Note that there is a link on each descriptor to DeCS Database

DeCS – Health Terminology

DeCS (acronym to Descriptores en Ciencias de la Salud) is the trilingual controlled vocabulary developed by BIREME based on MeSH - Medical Subject Headings applied in PubMed, with the purpose of permitting the use of common terminology for searching in three languages (Portuguese, English and Spanish), providing a consistent and unique environment for the retrieval of information regardless of the language.

In addiction to the original MeSH terms, DeCS also includes terminology in specific areas such as Public Health, Homeopathy, Science and Health, and Health Surveillance.

In every other aspect, both are roughly equivalent, including their dynamic character,incorporating new terms or changing their names,according to the evolution concepts within the subject areas.

The use of DeCS can be done directly from the homepage, accessing a menu with several options such as "About" (presentation of the service), "Search", "News" (that highlight the changes and developments ), "Early Editions" (a look at previous versions) and "User service" (for inquiries or suggestions of new terms).

To access DeCS:

• Through VHL - www.bvsalud.org - select DeCS at the VHL information sources menu
• Directly to DeCS homepage - http://decs.bvsalud.org/I/homepagei.htm

Fig. 12 - DeCS Homepage -http://decs.bvsalud.org

DeCS search requires previous setting of the language. One can use the interface in English and search for descriptors in Spanish, English, or Portuguese. It is not possible to search at the same time for descriptors in any language.

Fig. 13 DeCS Search Options

DeCS records have the same structure as MeSH records. They have hierarchical relations with more specific terms and provide "subheadings" which allows a sharper search through specific aspect of the subject matter (eg, death, sudden/etiology).

Fig. 14 - Full record of a DeCS Term

Fig. 15 - This example displays the tree hierarchy that includes the term - Death, Sudden

Search strategy for clinical trials

The criteria governing a search for health technology in LILACS is fundamentally the same as explained for PubMed. In other words, it will prioritize the recovery of randomized controlled trials (RCT), clinical practice guidelines and meta-analysis. However, such studies are not the most frequent in the region and unfortunately the search form does not provide an easy way to identify the records for these categories. There are two possible solutions; one is to review the results of a search manually deleting those records that are not relevant to our purpose. The other is the addition of a methodological filter to the search strategy. The former is the best choice, because the universe of references provided by LILACS is small and a well-formulated search will yield few results, making manual selection practical and accurate. In the IAHx interface there is already a filter to discriminate RCT. The RCT methodological filter can be used before or after the search strategy that represents the “question”.

Fig. 16 – RCT Methodological Filters for pre-selection - from LILACS Homepage

Fig. 17 – Set of retrieved RCT accordingly the methodological filter Note: Any search thereafter will be within the set of RCT

Fig. 18 – The Cluster Type of study includes RCT (Controlled Clinical Trials) Note: There are link to the citations indicated for each item of the clusters

The methodological filter for RCTs which is applied - as “Topic specific queries” in LILACS Homepage and in the cluster from the search result - is generated from the following search strategy:

Search strategy for RCT methodological filter in LILACS

There are no predefined clusters or filters in the iAH interface. However, the RCT search strategy can be pasted into one of the lines of the form and combined with the search strategy. Note that the query syntax is different among the two interfaces.

Search strategy for RCT to use in the IAH form and to combine with other strategy - IAH Interface

LILACS Search Tools

Main Tools to develop a search strategy

Developing a Search Strategy

Let's say we need to evaluate the effects of renal replacement therapy for patients with acute renal failure. The first step is always to identify controlled vocabulary terms to be used in the strategy. Start by the searching the INTERVENTION in DeCS (in our case, renal replacement therapy), for which we do not know the term used by the system. For this reason, we only use the sentence’s most relevant word, which is "replacement".

Fig. 19 – Searching in MeSH database – example with the word replacement

Fig. 20 – DeCS term to renal replacement therapy Note that this is the third record displayed in the search for “replacement”

With proper DeCS identification, we can start building a part of the strategy. Note that it is necessary to indicate the field search tag (MH for DeCS term), the colon : and then the term in double quotes '" "' when made up of two or more words.

Because search strategies can be quite long, it is not practical to edit them within the search box in the Web interface. The recommended practice is to use a simple text editor, such as Notepad, to edit and refine the search strategy, and then paste it into the search box. Microsoft Word is not a good choice for this task, because by default it replaces the straight double quotes understood by search engines with the curly, asymmetric double quotes.

As we have seen in PubMed search strategies, it is necessary to supply DeCS term with concept synonyms, the way they might appear in the title or abstract of an article linked by the Boolean operator OR. Note that when not indicated the search field, the TW index (Title + Abstract + DeCS Term) is considered by default. Accents are not necessary; they make no difference in the search.

It will also be necessary to add the synonymous terms in the other official languages of LILACS, Portuguese and Spanish. To find synonymous click on “Related English”.

"ñ" is interchangeable with "n"

We should also add synonyms and more specific terms that appear under the DeCS term. To this end, we have to go to the hierarchical tree structure of the term that we have already identified, from the link available in the Tree Number from the full record of the term.

Fig. 21 - Access to the tree structure of the DeCS Term – Renal Replacement Therapy See the record of the terms Renal Dialysis, Hemofiltration and Kidney Transplant

All the DeCS terms on the tree have links to their record description. Let’s see the full record of renal dialysis.

Fig 22 - Full record and tree structure for the DeCS term - renal dialysis

Each of the tree DeCS hierarchically subordinate terms found in DeCS is added to the strategy, in addition their own lists of synonyms and their equivalents in Portuguese and Spanish. Use the truncation signal ($) to avoid repetition. For example Biofiltration, Biofiltrations, Biofiltração, Biofiltración, etc.

The procedure should now be repeated for the second part of the strategy, corresponding to the POPULATION.

Both parts of the strategy should be in (parenthesis), and united among themselves by the Boolean operator AND before being introduced into the search box. In the IAHx interface (LILACS homepage) the operator AND is there by default and does not need to be entered in the strategy.

On the results screen it is possible to identify the used search strategy and the clusters accordingly to the total set of retrieved records, and the citations in short format – but we can switch to detailed format.

Fig. 24 – Search results in LILACS for the strategy and the RCT filter. Note the limited result for RCT

All items of the clusters have links to the indicated records. Let’s see the 27 citations in the short format. Remember, we can switch to detailed format to have the abstract and more information.

Fig 25 – Search results in LILACS filtered by RCT (clinical trials)Note the limited number of retrieved citations for RCT

In this strategy we have many words and terms on natural language without a tag field. When not indicated the search field, the TW index (Title + Abstract + DeCS Term) is considered by default as search field.

Exporting References

To export the last selection, go to Send Result, select Exportar, (i.e all references and RIS) to export to any reference manager software.

Fig 26 – Exporting References

Exercises

1) Do a simple search for Chagas disease.

2) Carry out a search for diabetes excluding what is related to gestational diabetes.

3) Do a search for all available information concerning the vaccination against the flu in Latin America and the Caribbean.

4) How many types of retroviridae are there?

5) It is necessary to know how many clinical trials have been carried out in Latin America and the Caribbean concerning the common flu in humans. Avian flu and pig flu (Influenza A H1N1) are outside our interest.

6) Do a search in PubMed for Chagas disease and check if LILACS retrieved some additional citation not retrieved in PubMed

7) Try exporting any of your results

Responses to exercises

1) Do a simple search for Chagas disease in LILACS

2) Carry out a search for diabetes excluding what is related to gestational diabetes.

3) Do a search for all available information concerning the vaccination against the flu in Latin America and the Caribbean.

4) How many types of retroviridae are there?

5) It is necessary to know how many clinical trials have been carried out in Latin America and the Caribbean concerning the common flu in humans. Avian flu and pig flu (Influenza A H1N1) are outside our interest.

6) Do a search in PubMed for Chagas disease and check if LILACS retrieved some additional citation not retrieved in PubMed