Formulation of a structured question

A well-structured question is essential in order to get the right clinical answer. It also facilitates the process of searching for evidence. A suggested approach uses five components (PICOD: Population, Intervention, Comparison, Outcome(s) and Design), as shown in Table 68.1.

Table 68.1 Components of structured clinical questions

IUS, intrauterine system. Produced by Bob Phillips, Chris Ball, Dave Sackett, Doug Badenoch, Sharon Straus, Brian Haynes, Martin Dawes since November 1998. Updated by Jeremy Howick March 2009.

The purpose of this step is to get clarity regarding the clinical question. Writing down the question in free form often makes it possible to break it down into a PICOD format. In practice, this may not always be feasible for all clinical questions, and missing out some elements of PICOD is not necessarily a cause for concern.

Searching the literature

Approximately 17,000 journals collectively publish over 1 million biomedical articles each year. Identifying relevant articles will require the use of apposite keywords (and their combinations) to search appropriate databases. A hierarchical approach to literature searching is recommended (Figure 68.3).

Figure 68.3 Hierarchical approach to literature searching. DARE, Database of Abstracts of Reviews of Effectiveness; RHL, Reproductive Health Library; NeLH, National electronic Library of Health.

Source: Khan and Coomarasamy (2003). NeLH, National electronic Library for Health; RHL, Reproductive Health Library.

The first step is to look for an up-to-date professional guideline that has been developed on the basis of systematic appraisal of available evidence. Table 68.2 lists some sources of guidelines and evidence summaries. The Royal College of Obstetricians and Gynaecologists (RCOG) has long acknowledged the need to update clinical practice on the basis of research findings. Since 1973, the RCOG has regularly convened study groups to address important growth areas within the specialty. These groups have met, evaluated the results of research and conducted in-depth discussions on a variety of topics. These discussions have shaped the development of clinical recommendations which were initially based on consensus. Over the years, this approach has been modified in order to produce genuine evidence-based guidelines. To be effective and relevant, guidelines must fulfil fthe following three essential criteria.

Table 68.2 Sources of guidelines and evidence summaries (relevant for gynaecology)

It is generally anticipated that national guidelines will, in turn, be used as a basis for the development of local protocols and guidelines in conjunction with local commissioners and providers of health care as well as service users. These should take into account the specific needs of local service provision and the preferences of the local population.

In the absence of credible evidence-based guidelines, the next step would be to search for an up-to-date, good-quality, systematic review. Some sources of systematic reviews are given in Table 68.3.

Table 68.3 Sources of evidence

WHO, World Health Organization; CRD, Centre for Reviews and Dissemination; DARE, Database of Abstracts of Reviews of Effectiveness.

Apart from the traditional sources of systematic reviews, such as the Cochrane Library and DARE, MEDLINE and Pubmed have now become a rich source of systematic reviews. Pubmed contains a systematic review filter within Pubmed Clinical Queries (http://www.ncbi.nlm.nih.gov/entrez/query/static/clinical.shtml), and MEDLINE has the indexing term ‘reviews, systematic’ as a ‘publication type’.

If no systematic reviews are identified, or if reviews are out-of-date, non-systematic or of marginal relevance to the clinical question, it is necessary to continue the literature search for primary studies. Table 68.3 provides a list of important sources of primary literature.