Trajectory analysis in clinical research.

Trajectory analysis investigates patterns of change over time of variables across various fields, including clinical and public health research. This method is useful for understanding the evolution of behaviors, conditions, and biomarkers (such as serum creatinine, blood pressure, etc.) over time. In medicine, by examining trajectories, researchers can identify distinct clinical patterns and assess the impact of risk factors and interventions on these patterns. This paper explores some theoretical and practical aspects of trajectories analysis by focusing on group-based trajectory models (GBTM) and emphasizing the importance of this approach in clinical research by providing guidance on its implementation using STATA software.