Loss of chance: the uncertainty of the event or the uncertainty of the conduct? Case series and medicolegal considerations

Background: The concept of damages for loss of chance originated in France in 1877 and was adapted to healthcare in 1962. In Italy, it was first introduced in healthcare liability in 2004, with Civil Court of Cassation decision No. 4400. Italian jurisprudence recognizes the loss of chance as an independent, legally and economically assessable damage, distinct from the actual outcome lost. The landmark St. Martin Judgments of 2019 further established that such damages can be claimed if they involve appreciable, serious, and consistent values. This requires proving a causal link between the conduct and the lost chance, based on established civil law criteria. Case report: 1) a 71-year-old man whose lung carcinoma was not diagnosed in time, leading to a significant reduction in survival chances. 2) a woman whose breast cancer diagnosis was delayed, resulting in a more advanced stage and decreased survival prospects. Discussion: In medical professional liability, the Supreme Court requires a high probability or certainty of causation for recognizing the causal link between wrongful conduct and damage. The assessment involves proving both the causal link and the reasonable probability of a lost opportunity's realization. Hypothetical damage is insufficient for compensation. Conclusions: The compensability of loss of chance relies on proving the causal link between the negligent act and the uncertain event, where the impact on the patient's non-pecuniary sphere is significant. Medicolegal practice faces challenges in distinguishing between causality and damage, which can lead to confusion between biological damage and damage from loss of opportunity.