Canine epilepsy: the importance of high quality studies

Back in 2014, we published a blog detailing the difficulties encountered when conducting a systematic review of canine epilepsy treatment. Two years on and the group from the Royal Veterinary College are still working hard to gain insight into the safety and efficacy of anti-epileptic drugs. In BMC Veterinary Research this month, the group have published the first ever systematic review and meta-analysis of the adverse effects of anti-epileptic drugs in dogs, but have experienced similar issues.

What is canine epilepsy?

A chronic condition characterized by recurrent seizures, canine epilepsy is one of the most common diseases reported in dogs, affecting approximately 50,000 in the UK alone. The condition can be very distressing for both the dog and their owners, but an array of anti-epileptic drugs (AEDs) are available to help manage the condition. Whilst the efficacy of each drug has not been well defined, the original systematic review provided valuable information to address this.

What were the aims of this new study?

Following on from the original systematic review of canine epilepsy studies, this new study looks specifically at the adverse effects of AEDs. The inclusion of a meta-analysis is also a significant advance, allowing for a more detailed analysis of the results. Co-author of the study, Marios Charalambous, describes the methodological process:

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‘We recruited systematic and statistical methods to combine, compare and summarize the results of independent studies and, therefore, create more objective and reliable conclusions based on the current evidence. It was a time-consuming, demanding and challenging process, but we are sure that we provide the clinicians now with essential information which they can use for daily practice.’

Reporting standards: a major limitation

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As with the previous review by the group, and as is common with many systematic reviews, this study encountered a number of difficulties with the data available for analysis. There are two main problems – the quality of the study design and the quality of the reporting. As the authors state in their paper:

‘Comparisons between other AEDs were not possible as a considerable amount of studies lacked power calculations or adequate data to allow further statistical analysis.’

In many cases, while the quality of the studies are good, the level of evidence is low because of the nature of the study and the risk of bias. While these studies provide valuable data, they are not as useful as the gold-standard randomized controlled trial. In this study only 12.5% of studies were deemed to be at the lowest risk of bias and more studies are needed, as confirmed by the Director of the RVC Small Animal Referral Hospital, Prof. Holger Volk:

‘This study highlights the importance of the need for trials which provide high quality evidence in order to have more reliable and objective results about the safety and tolerability of the AEDs in veterinary medicine.’

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The second problem is the inadequate reporting of studies – where the research conducted may be of a high standard, but the necessary details are not included in the paper to allow further analysis. This is frustrating because good quality research is being hindered by the poor reporting. In recent years, there have been significant efforts to ensure that this issue is prevented, through the development and adoption of reporting guidelines such as ARRIVE for animal research and CONSORT for randomized controlled trials. BMC continues to endorse these reporting guidelines in the hope that future studies are reported in sufficient detail to allow for complete interpretation and further analysis. Indeed, this paper is an example of research that has benefited from adherence to the PRISMA reporting guidelines for systematic reviews and meta-analysis. Through adherence to these guidelines, future researchers will have the necessary details available to them to fully assess and critique the study. More information regarding BMC’s commitment to reporting guidelines can also be found in another recently published blog on the BMC Series.

The outcomes

Despite the difficulties encountered, the authors have been able to produce a high quality resource for veterinary scientists. They were not able to draw many firm conclusions due to the quality of the available data, but they were able to make suggestions as to the AEDs with the best safety profiles. Dr. Dave Brodbelt, Senior Lecturer in Companion Animal Epidemiology concludes:

‘This is a valuable addition to the body of literature on canine epilepsy, highlighting safety issues and adverse events related to its management and adding further depth to the evidence base relevant to practicing vets.’

 

Further information about the authors and the study can also be found at the RCV Press Office site

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