The challenges facing surgical and vascular RCTs are well known internationally: high cost, regulatory burden, slow recruitment, scepticism among clinicians, and lack of infrastructure. ^, The consequence of these challenges is stark: vascular and endovascular treatments and technologies are increasingly adopted into routine care based on registries, short term safety data, or uncontrolled studies. Patients are routinely exposed to interventions without any robust evidence of medium or long term effectiveness.

In a New England Journal of Medicine Sounding Board article by Collins et al. , the authors are unambiguous: observational data, however large, cannot substitute for randomisation when treatment effects are moderate, as they almost always are in vascular diseases, especially peripheral arterial disease. Randomisation uniquely balances known and unknown confounders, allowing causal inference that no other study format, however sophisticated, can deliver. The “magic of randomisation” is not a cliché; it is the only reliable way to determine whether a treatment is effective (not just efficacious) and safe in the real world.

Registries are valuable, but primarily for monitoring safety, identifying rare adverse events, and generating hypotheses; they cannot appropriately answer efficacy or effectiveness related clinical questions or hypotheses. Both the efficacy and effectiveness of a treatment can only be truly assessed via a randomised trial. Efficacy trials (explanatory trials) determine whether an intervention produces the expected result under ideal circumstances. Effectiveness trials (pragmatic trials) measure the degree of beneficial effect under “real world” clinical settings. Yet, vascular clinicians tend to lean on non-randomised evidence and or small efficacy driven highly selective RCTs when deciding on the adoption of new devices or techniques. This is not enough. Without large, effectiveness driven RCTs, we risk misinforming patients, wasting public resources, and entrenching ineffective or sometimes harmful practices.

A persistent barrier in surgical and vascular RCTs is the assertion from surgeons or other interventionists that they are “not in equipoise” about the question being tested. ^, Too often, clinicians feel they already “know” which treatment is superior and therefore resist randomisation. This stance is misguided. As Freedman argued in his seminal 1987 paper, equipoise exists at the societal level, not solely within the mind of the individual clinician. The relevant question is not whether I believe that treatment A is better than treatment B, but whether the community of informed clinicians and scientists has genuine uncertainty. In vascular disease, that uncertainty is almost always present because robust evidence is almost always lacking.

We therefore owe it to our patients, our health systems, and society to offer participation in trials whenever a relevant question is being tested. The General Medical Council in the UK is explicit: doctors must offer patients the opportunity to participate in relevant, publicly funded trials. This is not optional. It is part of our professional duty.

One reason why clinicians sometimes distrust RCTs is that smaller efficacy driven studies often fail to answer the questions we face in day to day practice. Our recent RANDOMisation Screening for Drug coated or Drug Eluting Device Randomised Trials Among Patients Undergoing Endovascular FemorOPopliteal Procedures (RANDOM STOP) study demonstrated this clearly: efficacy driven RCTs typically exclude most patients we treat, use narrow entry criteria, and adopt surrogate or highly specific outcomes that do not reflect what matters in practice (

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). They may demonstrate biological efficacy in carefully selected cohorts, but they cannot inform real world decision making.

By contrast, large pragmatic effectiveness driven RCTs are designed to reflect everyday clinical care. Bypass versus Angioplasty in Severe Ischaemia of the Leg Trial (BASIL)-2, BASIL-3, Best Endovascular versus Best Surgical Therapy in Patients with Critical Limb Ischaemia (BEST-CLI), Paclitaxel coated versus uncoated devices for infrainguinal endovascular revascularisation in patients with intermittent claudication (SWEDEPAD), Endovascular vs. Open revascularisation in severe oCClusive aorto-iliac disease (EVOCC), Does carbon dioxide reduce the chance of kidney problems in minimally invasive (endovascular) artery treatments? (KID), Women’s Aneurysm Research: Repair Immediately Or Routine Surveillance (WARRIORS), Metformin Aneurysm Trial (MAT), and other current trials in the UK and beyond are excellent examples. They include broad patient populations, test interventions in the settings where they are actually delivered, and use outcomes that matter to patients, such as limb salvage, survival, and quality of life. Importantly, they are randomised, ensuring balanced comparisons that registries can never replicate.

Common sense would dictate that healthcare systems and regulators should more tightly restrict vascular devices before demonstration of effectiveness to only be used within appropriately designed RCTs, but this is currently not happening.