Trajectories of FEV1 After Lung Transplantation: Determinants and Clinical Outcomes

Chronic lung diseases affect about 500 million individuals and are the third leading cause of death worldwide, accounting for 7% of all mortality. They drive the growing number of individuals with end stage lung disease (ESLD), a public health issue with socioeconomic consequences.

For individuals with ESLD, lung transplantation is the best, or only treatment option with increased pulmonary function and quality of life. Lung recipients remain however particularly at risk, with a median patient survival of around five years, which is much lower than other organ recipients, such as kidney, heart or liver recipients. Adequate monitoring of the lung recipient is therefore crucial to optimize the allograft longevity.

The forced expiratory volume in one second (FEV1) is the standard to monitor the lung function after transplantation, and is used to evaluate the stage and severity of lung allograft diseases. However, according to a literature review we performed, the very few studies that have investigated the FEV1 evolution, and its relationship with outcomes such as death or chronic lung allograft dysfunction, were commonly based on cohort with insufficient data variety and completeness. Importantly, these studies lacked external validation, multidimensional approach, and none has attempted to identify the main profiles of FEV1 trajectories and their associated parameters. As such, the determinants and long-term outcomes of FEV1 trajectories are still poorly understood.

A multidimensional, trajectory-based approach may help unveil clinically relevant organ function profiles among lung recipients. Indeed, several studies have shown the potential existence of underlying trajectories of transplanted organs' function and diseases, and their associations with outcomes and relevance for patient management, such as in kidney or heart transplantation. These studies used a unsupervised approach, which permitted to erase any preconceived clinical ideas. Overall, this approach has shown its value in several medical specialties, in particular in image analysis, oncology, or cardiology.

Therefore, the goal of this study was to identify and validate the FEV1 trajectories after lung transplantation, as well as their determinants and outcomes, using an international cohort of lung recipients, with a protocol-based collection of FEV1 repeated assessments and clinical, biological, histological and immunological data.