In clinical medicine, the term prognosis refers to the risk of future health outcomes for people with a particular disease or health condition. Therefore, a prognostic study is an observation of a population with a given baseline health status, thus mining the relationship between baseline characteristics and future outcomes. Prognostic study findings provide relevant evidence for clinical decision-making, policy development, discovery and evaluation of novel methods for patient management. However, there are great differences in the objectives, design and implementation, interpretation and application of results when developing prognostic studies. In order to better understand the needs of prognostic studies, rationally design prognostic studies and apply their results, prognostic studies should be divided into four different types: (1) Basic prognostic studies, with the purpose of exploring the differences in certain health outcomes between different diseases or health conditions. (2) The study of prognostic factors, with the purpose of exploring the differences in certain health outcomes between different disease characteristics under the same disease state. (3) Predictive model research, with the purpose of establishing and validating a certain model or scoring system to predict patient outcomes. (4) Stratified medical studies (predictor studies) with the aim of finding a group of patients who respond better or worse to a specific intervention.
