Elaboration and sharing of generic search strategy modules in the development of oncology evidence-based clinical practice guidelines.

S. Guillo, A-G. Guy, L. Bosquet, G. Gory, and the SOR Steering Committee
French National Federation of Comprehensive Cancer Centers (FNCLCC)

Context

The “Standards, Options & Recommandations” (SOR)

SOR are evidence-based clinical practice guidelines in oncology developed by experts and methodologists since 1993.

Since 2001, a scientific literature monitoring process has been defined to identify the need for updating the guidelines.

The effective search for data is primordial in this setting to ensure that the guidelines are based on systemic reviews of the existing pertinent literature.

The Evidence-based-medicine (EBM) approach

Clinical problems can be formulated using the PICO model: 
Patient and Pathology
Intervention
Compared intervention
Outcome

The efficacity of interventions are evaluated using specific study designs, eg. randomised controlled trials (RCT).

The EBM approach consists in synthesizing the best available evidence.

SOR search strategies

Since the beginning of the SOR program, an important number of search strategies have been developed and saved. Some of these strategies contain identical or similar parts. In addition, for a unique clinical question, different strategies sometimes coexist.

SOR search strategies have a modular structure, based on the PICO model, which enables the different modules to be adapted and combined to define new search strategies.

Objective 

To optimise literature searching in the guidelines development process by providing easily accessible search strategy modules for Medline®, Embase®, and the Cochrane Controlled Trials Database® (CCTR®). 

The main aims are :
-	to ensure systematic and homogeneous literature searching step for the guidelines development process
-	to avoid unnecessary duplication of effort between working groups
-	to optimise the existing modules

Methods

The items in the PICO model were sub-divided in the following way, taking into account how search strategies are constructed and the structure of the bibliographic databases: 

1.	“Patients and Pathology” were considered in terms of “pathology”, “tumour stage” and “population” separately
2.	Both “interventions” (tested and control) were considered in the “intervention” module and management step was separated from this module.
3.	Since “outcomes” are rarely indexed as keywords in biomedical databases, this module was not included
4.	A module to specify the type of studies was elaborated because it represents an effective way of limiting a literature search in this setting

The existing search strategy were assessed to identify the different modules included in each strategy and the strategies were indexed with the names of these modules. When several modules concerning the same topic were found, we tested them to identify the best and it was designated as the ‘reference’ module.

An Access® database was created, providing a unique searchable access to the modules, thus enabling:
-	the identification of search strategies containing generic reference modules that can be used to create new strategies
-	modules to be updated

A consultation procedure was developed to enable users to search the database and to explain how to update it as new strategies are elaborated. 

Results

Typology of the SOR searching modules

The typology of the SOR searching modules are based on the PICO model:

1.	“PATHOLOGY” is composed of:
a.	“tumour site”, eg skin, or “other pathology”, eg pain, anemia.
b.	“histologic type”, eg adenocarcinoma, melanoma 
2.	“TUMOUR STAGE”, eg in situ, metastatic
3.	“POPULATION”, eg elderly, child, women
4.	“MANAGEMENT STEP”, eg diagnosis, staging, treatment, follow-up
5.	“INTERVENTION”, eg endocrine therapy, letrozole, chemotherapy
6.	“METHODOLOGICAL FILTER” combines 
a.	“type of study”, eg controlled clinical trial 
b.	“other methodologic aspects of the study”, eg double blind trial, sensibility or specificity of a diagnostic test
c.	“exclusion filter” allows to exclude the irrelevant informations, eg case reports, letters

Indexation of the SOR searching modules
The strategies have been indexed using this typology and are stored in the Access® database. The ‘reference’ module i.e. the last version of a module is also indexed. Since we are continuing to improve the modules, the reference module need to be indexed as such.

As each database has its specific thesaurus, the modules are specific for a given database (Medline®, Embase®, CCTR®)

Elaboration of a new search strategy 

To elaborate a new search strategy, we:

1.	formulate the question using our adaptation of PICO. The minimum information required is the pathology (tumour site for a cancer) and either the management step or the tested intervention.

Example: Efficacy of radiation therapy in non metastatic breast cancer

Pathology = breast carcinoma
Tumour stage = non metastatic
Intervention tested = radiotherapy
Best type of study = randomised controlled trial

2.	search the database to identify the strategies that contain the pertinent reference modules (see figure 1)

Each strategy is indexed using fields for each type of module. The searchable fields are, therefore: 
-	pathology
-	tumour stage
-	population
-	management step
-	intervention
-	methodological filter

It is also possible to search for:
-	the bibliographic database, eg. Medline®
-	the ‘reference’ modules

Example: search of the non metastatic reference module for Medline®
Strategies corresponding to the required database and containing modules specific for the clinical question can thus be identified (see figure 2).

3.	associate these modules with the boolean operators (AND, OR, NOT) (see figure 3). The search strategy needs to be finalised with further work, for example: ‘breast neoplasms’ (pathology) + ‘rt.fs.’ (intervention) will become ‘breast neoplasms/rt’ in the final search strategy (see figure 4).

Update of the database

New strategies are progressively created, when new literature searches are needed. If an existing module is improved (example: adding of ‘carcinoma.ti.’in the pathology module, see figure 4) or if a new module is elaborated, the ‘reference’ modules are updated. These strategies are indexed using the names of the different modules they contain and stored in the database (see figure 5) .

The medical librarian is responsable for this updating process. 

Conclusion 
The development of evidence-based guidelines is an ideal setting for this modular approach to literature searching. The storage of the modules in a central database facilitates their access by the guidelines working groups for elaborating specific search strategies, building on previous work. This approach avoids unnecessary duplication of effort and leads to more systematic, homogeneous search strategies for the guidelines produced within our guideline programme and is, therefore, a useful tool.

The database was created in October 2003 and has already been found useful in our setting. We are working towards a situation where the individual modules will be stored in the database, thus facilitating a more direct access to them. The database will then become  a ‘box of modules’.

In the EBM setting, it would be very useful to have the possibility to search keywords for ‘Pathology’, ‘Tested intervention’, ‘Control intervention’, and ‘Outcome’ in specific fields, as it already exists for ‘Publication type’ and ‘Population’ in Medline® 

It is not possible to automatise all aspects of the elaboration of a search strategy and human intervention is always necessary.

References
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2.Fervers B, Hardy J, Blanc-Vincent MP, Theobald S, Bataillard A, Farsi F et al. SOR: project methodology. Br J Cancer 2001;8
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6. Université de Liège département de médecine. Introduction à l' "Evidence-Based Medicine" (EBM) http://www.ebm.lib.ulg.ac.be/prostate/ebm.htm#étude
7. University of Alberta. Evidence-based medicine tool kit. Available: http://www.med.ualberta.ca/ebm

Thanks to…
Margaret Haugh for proof reading
Sophie Rousmans for testing the consultation procedures
Daphné Gouvrit for her technical assistance