Evidence synthesis – Vive la révolution

I posted a tweet on the 18th March “For those doubting the value of rapid reviews then the COVID-19 pandemic should make you reconsider.” I pointed out that the Centre for Evidence-Based Medicine (CEBM) in Oxford had produced the COVID-19 Evidence Service and is producing multiple rapid reviews (RRs). The tweet finished with “We simply do not have time to wait 6-24 months for guidance“**.

Systematic review (SR) producers, typically resistant to RRs, have more recently started to embrace them. For instance Cochrane have started a RR Methods Group and have now just released a COVID RR site.

This has got to be applauded.

But what does it say about the ‘systematic’ versus ‘rapid’ debate?

SR producers would invariably want to be involved in producing supporting evidence for the COVID-19 ‘fight’. However, it is clear that waiting 1-2 years for a response is useless for front line staff and policy makers needing as much evidence as possible to inform difficult and immediate decisions. The logical step – for fear of being seen as irrelevant in the biggest global health crisis in years – is to embrace the RR approach. Previous concerns (real or imagined) around quality have been set aside, at least for now. Is the battle for relevance more important than methodological purity?

Is the genie out of the bottle?

These are extreme times and resources are constrained (eg time) but is that not always the case? There are never enough evidence reviews, principally due to a lack of resource. Different times, different constraints. Is it better to do 25 RRs or 1 SR? I’ve always been of the view that the RRs give much better value. I’ve also been of the opinion that you should only do a SR after a RR and where there is good reason to believe a SR (with the significant resource demands) would add value.

Will it be simple for SR producers to return to the old ways? Telling clinicians and/or policy makers that they’ll get their answers in 12+ months? The COVID-19 crisis has disrupted how we do evidence synthesis and time will tell how this pans out. If RRs (done by the Oxford COVID-19 Evidence Service, Cochrane or whoever) are shown to be demonstrably problematic then there is a case to return to the old ways. But if, as I suspect, the RRs are robust, timely and useful it’ll be a difficult ‘sell’ to users that – instead of reviews done quickly and cheaply – we’re returning to slow and expensive.

Vive la révolution.


** Conflict of Interest Statement: Trip works with CEBM and the Evidence Service


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