How has the COVID-19 emergency tested evidence-Based Medicine (EBM)? In a recent article, Trisha Greenhalgh argued that the philosophical assumptions on which EBM is based – a singular truth, ascertainable through empirical enquiry; a linear logic of causality; rigour defined primarily in methodological terms; a deconstructive approach to problem-solving – did not withstand the outbreak of the COVID-19 pandemic.
A pandemic – continues Greenhalgh – can be addressed and investigated in different ways. Indeed, research issues such as drug therapies and vaccines are susceptible to randomised controlled trials. However, some issues cannot be reduced to such research logic:
Were care home deaths avoidable? Why did the global supply chain for personal protective equipment break down? What role does health system resilience play in controlling the pandemic? And so on.
It is challenging to address these questions with a controlled experiment, designed to produce a statistically significant and widely generalised answer: prevention, in particular, is difficult to reduce to this logic, having to sustain a widespread and lasting change of behaviour in an entire population:
When implementing population-wide public health interventions-whether conventional measures such as diet or exercise, or COVID-19 related ones such as handwashing, social distancing and face coverings-we must not only persuade individuals to change their behaviour but also adapt the environment to make such changes easier to make and sustain.
While EBM has always tended to classify public health prevention interventions as “low methodological quality”, it is also true that the EBM paradigm alone has proved inadequate to cope with a pandemic. For this reason, it is necessary to accept another paradigm, more suitable for the historical moment we are living: at population and system level, where we cannot pursue the objectives of certainty, predictability and linear causality, we must embrace another epistemology to study how to deal with situations that are not certain, predictable and linear. Looking at complex systems becomes a necessity to address the public health challenges that lie ahead.
In the current fast-moving pandemic, where the cost of inaction is counted in the grim mortality figures announced daily, implementing new policy interventions in the absence of randomised trial evidence has become both a scientific and moral imperative. Whilst it is hard to predict anything in real time, history will one day tell us whether adherence to “evidence-based practice” helped or hindered the public health response to Covid-19-or whether an apparent slackening of standards to accommodate “practice-based evidence” was ultimately a more effective strategy.