The volume-outcome relationship in hospitals - Lessons from the literature

Concentrating the supply of hospital activity in larger hospital units is often presented as a means to improve the quality of care, but the extent of the relationship and the direction of causality between hospital volume and health outcomes is still a matter for debate. The literature review carried out by the IRDES shows that for certain procedures and interventions, particularly complex surgery, there is a real possibility of improving outcomes by increasing activity volumes. The presence of a learning curve at both the individual and hospital level (transfer of knowledge, organisation of work) appear to explain a large part of this correlation. In certain cases, however, the alternative hypothesis of selective referral, according to which patients are directed towards the hospitals with the best outcomes, cannot be disproved.