Addressing unwarranted clinical variation: A rapid review of current evidence.

Wennberg's classification framework is commonly cited in relation to classifying variation, but no single approach is agreed upon to systematically explore and address UCV. The instances of UCV that warrant investigation and action are largely determined at a systems level currently, and stakeholder engagement in this process is limited. Lack of consensus on an evidence-based definition for UCV remains a substantial barrier to progress in this field.