Systematic reviews and international development by Prof. Paul Garner

In this short video, Prof. Paul Garner discusses the relevance of systematic reviews to international development. Paul has a wealth of experience of systematic reviews, having led a programme of research coordinating a network of over 300 people synthesising research to inform global, regional and national policies in tropical infections and conditions relevant to middle and low income countries. He has worked at the Liverpool School of Tropical Medicine since 1994. More information is available on his staff profile.

Systematic reviewing describes an approach to methodologically mapping out the available evidence, critically appraising the evidence and synthesising the results. Systematic reviews assist decision and policy making in international development. The Department for International Development (DFID) has worked with the International Initiative for Impact Evaluation (3ie) to set up a searchable database of systematic reviews on development issues. The database is available online.

Cochrane Reviews

Another important source of systematic reviews is the Cochrane Collaboration, which is an international network of more than 28,000 people from over 100 countries.  They prepare, update, and promote the accessibility of the 5,000 Cochrane Reviews published to date. Cochrane Reviews are systematic reviews of primary research in human health care and health policy, and are internationally recognised as the highest standard in evidence-based health care. They investigate the effects of interventions for prevention, treatment and rehabilitation. They also assess the accuracy of a diagnostic test for a given condition in a specific patient group and setting. Cochrane Reviews are published online in The Cochrane Library.

In 2013 The Cochrane Collaboration celebrated 20 years since its official foundation in 1993. Posted on their youtube account, this short video has a  retrospective look at the Collaboration’s beginnings and achievements of the past two decades. It includes interviews with many Cochrane contributors, past and present.

Each systematic review addresses a clearly formulated question. All the existing primary research on a topic that meets certain criteria is searched for and collated, and then assessed using stringent guidelines, to establish whether or not there is conclusive evidence about a specific treatment. The reviews are updated regularly, ensuring that treatment decisions can be based on the most up-to-date and reliable evidence. More information can be found at the Cochrane website.

Examples

Two examples of Cochrane reviews relevant to international development are Taylor-Robinson et al. (2012) and Abba et al (2011).

Taylor-Robinson et al. (2012) focus on deworming. It found that screening children for intestinal helminths and then treating infected children appears promising, but the evidence base is small. Routine deworming drugs given to school children has been more extensively investigated, and has not shown benefit on weight in most studies, except for substantial weight changes in three trials conducted 15 years ago or more. Two of these trials were carried out in the same high prevalence setting. For haemoglobin and cognition, community deworming seems to have little or no effect, and the evidence in relation to school attendance, and school performance is generally poor, with no obvious or consistent effect. The interpretation of the authors of this data is that it is probably misleading to justify contemporary deworming programmes based on evidence of consistent benefit on nutrition, haemoglobin, school attendance or school performance as there is simply insufficient reliable information to know whether this is so.

Abba et al (2011) focus on Rapid Diagnostic Tests (RDTs) for Plasmodium falciparum malaria which use antibodies to detect either HRP-2 antigen or pLDH antigen, and can improve access to diagnostics in developing countries. The conclusion states that the sensitivity and specificity of all RDTs is such that they can replace or extend the access of diagnostic services for uncomplicated P. falciparum malaria. HRP-2 antibody types may be more sensitive but are less specific than pLDH antibody-based tests, but the differences are small. The HRP-2 antigen persists even after effective treatment and so is not useful for detecting treatment failures.

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