Is it safe to conduct interventional research? In clinical settings working under pressure we must first consider system tolerated avoidable risks in care

All health systems, even those offering 'best practice' care, routinely expose patients and staff to some possibility of avoidable harm. Building on earlier theory we call these "System Tolerated Avoidable Risks in Care" (STARC), explain how they become normalised and normalised and consider the implications for safety and quality interventions. Clinical settings under pressure become progressively degraded through the accumulation of system-induced workarounds that increase the potential for harm but become accepted as everyday practice. These tolerated, largely unremarked operating conditions and associated risks help explain why quality-improvement efforts, implementation and technology or therapeutic intervention programmes often fail or may even cause further harm. We recommend first assessing how degraded a care system is and directly tackling underlying system deficits to stabilise highly dysfunctional systems before intervention in the worst cases. In other cases, we recommend deploying foundational co-interventions in addition to any specific new intervention when operating conditions manifest clear threats to patient safety. Such planning when considering an intervention we believe will increase the likelihood of success, promote patient safety as an important element of interventions and subsequently provide a more complete understanding of what is needed to support adoption at scale and sustained patient benefit.