Why Systematic Reviews are the Building Blocks for Changes in Policy and Practice


Earlier this year, we discussed the importance of the Systematic Review to vision research. This month we asked Pirindha Govender, to give us her perspective from the standpoint of a researcher who has been deeply involved in the process.

VII: How does the Systematic Review (SR) fit into the research landscape?

PG: Traditionally, one would investigate an area of interest by conducting a literature review on a question. A SR should not be confused to be the same thing, but should be regarded as the highest form of research, a study of studies. It is a transparent, rigorous process of interrogation of existing research to answer a specific question. It is this research that can change policy and practice and therefore is a vital step to obtain answers to questions. I find that the SR is a way to make gaps in evidence blatant or obvious. Clinical practice guidelines are built on the backs of SRs. Without good quality evidence, we cannot advocate for specific intervention and management strategies.

VII: What value does the SR process add to existing research?

PG: Even though a study already exists, it does not mean that this research was conducted using the most rigorous scientific process to achieve the results. In fact, in the process of conducting certain SRs, I have discovered various gaps in the quality of studies that we would have otherwise regarded as being of high quality.

Very often in research we would like to draw conclusions from studies on perhaps a management strategy or we would like to suggest a global distribution of a particular condition.  The SR is the only way that allows us to do this by comparing “apples to apples”.  It allows us to examine issues across studies that are of similar quality and design. It is only then that we can make conclusions. SRs also go beyond just peer-reviewed evidence – they can consider unpublished research which could contain evidence that adds value to the area of investigation.

VII: What are the challenges of conducting SRs?

PG: Many people think that it is as simple as conducting a traditional literature review. The SR goes far beyond this. Through a SR, we systematically search the evidence, identify potential studies that answer the research question, screen and select the most appropriate studies, and appraise these studies according to defined criteria to determine scientific rigour. Only then can we synthesize the evidence to answer the research question.

It’s a very collaborative process. You would need at least two researchers to be responsible for the screening and review of existing evidence.

There are challenges:

  • A large number of databases need to be consulted to explore the research question. Access can sometimes be a limitation. In some cases, limiting the search to only those databases that you have free access to within an institution can lead to a bias in the review.
  • It can be resource-intensive, especially when the topic of investigation yields hundreds of studies. Since you need to adhere to a strict protocol of screening and appraisal, there are absolutely no shortcuts and it can take a significant amount of time at each stage of the review process.

VII: You recently completed a SR of several papers on the impact of poor vision on a number of population segments. What do you hope the outcome of this work will be and what next steps would you like to see related to this work going forward?

PG: One of the most significant advocacy tools is to provide the evidence of impact of Uncorrected Refractive Error (URE) on individuals. Whether it is in terms of finance, quality of life, or academic performance, providing policy makers the figures and conclusive evidence that indicate the detrimental effects of URE on individuals is what is needed to mobilize efforts to create or upscale efforts to alleviate avoidable blindness.  One of the common threads through all of the SRs, was the scarcity of high-quality, well-designed studies on the impact of URE on children, adults, drivers, presbyopes, and the elderly.

Studies do exist, however, there are not enough high-quality studies to formalize a consensus.  You need this consensus to convince people of validated impact.

I think in many cases, these types of studies are lacking because of the ethical issues around conducting randomized control trials (RCT) in which you compare providing a correction versus depriving an individual of correction. I am noticing that novel approaches are being adopted to ensure that ethical rights are being respected and rather than depriving individuals of correction, they are delaying the provision. This way, no one is deprived of correction and all rights are respected.

We should be encouraging researchers to take up this challenge of conducting RCTs to determine the impact of correction on quality of life, academic performance, activities of daily living, etc.

Another gap that has become evident in the SRs is the limited number of longitudinal studies (a study over time).  They can be very resource-intensive, however, they yield invaluable data that is not widely available. I would definitely encourage researchers to conduct longitudinal studies to observe changes over time.

VII: How can vision advocates make the best use of the research that is currently available on the issue?

Current research needs to be translated into messages that can be used to educate people on various significant public health issues like myopia and diabetes.  We also need to create access to the information and use it for primary prevention.

Vision advocates need to repackage the research so that they can reach people from all walks of life, young and old, lay people, who can adopt various lifestyle changes that can bring about better quality of life and greater productivity.

VII: What additional research would you like to see that could help bring good vision to more people around the world?

PG: I think researchers need to use the gaps identified as catalysts for change in the research approach. They can go beyond the conventional cross-sectional observational studies and delve into higher quality methodological approaches and conduct RCTs and longitudinal studies.

We should be looking at conducting research on, and in, the populations most in need and should be looking at both qualitative and quantitative approaches to understand best the cause and effect of vision impairment and blindness.

Especially now, when we are aware of the potential devastating impact of myopia and high myopia on populations, we should be trying to elucidate the best evidence to bring about change in people’s understanding of myopia and most importantly, behaviour change that can change the path of the imminent public health crisis.