The aim of this review is to describe the different statistical methods used in estimating the minimal clinically important difference (MCID) for the assessment of quality of life (QOL)-related and clinical improvement interventions, along with their implementation in cardiothoracic surgery. A thorough literature search was performed in three databases (PubMed/Medline, Scopus, Google Scholar) for relevant articles from 1980 to 2022. We included articles that implemented and assessed statistical methods used to estimate the concept of MCID in cardiothoracic surgery. MCID has been successfully implemented in several medical specialties. Anchor-based and distribution-based methods are the most common approaches when evaluating the MCID. Nonetheless, we found only five studies investigating the MCID in the context of cardiothoracic surgery. Four of them used anchor-based approaches, and one used both anchor-based and distribution-based methods. MCID values were very variable depending on the methods applied, as was the clinical context of the study. The variables of interest were certain QOL measuring questionnaires, used as anchors. Multiple anchors and methods were applied, leading to different estimations of MCID. Since cardiothoracic surgery is related to important perioperative morbidity, MCID might represent an important and efficient adjunct tool to interpret clinical outcomes. The need for MCID methodology implementation is even higher in patients with heart failure undergoing cardiac surgery. More studies are needed to validate different MCID methods in this context.
Keywords: MCID; QoL; cardiac surgery; heart failure; minimal clinically important difference; quality of life; thoracic surgery.