Pre-Diagnosis FEV1 Decline Predicts Mortality in Lung Transplant Recipients

Predicting the Unpredictable in Chronic Lung Allograft Dysfunction

Long-term survival following lung transplantation remains significantly lower than that of other solid organ transplants, primarily due to the development of chronic lung allograft dysfunction [1]. This clinical entity serves as an umbrella term for various immune-mediated pathways that result in progressive, often irreversible, graft injury [2, 3]. While current maintenance strategies frequently utilize tacrolimus (a calcineurin inhibitor used to suppress T-cell mediated rejection) to reduce the risk of chronic dysfunction, these interventions do not always translate into improved long-term survival [4]. Despite the use of anti-inflammatory agents like azithromycin to stabilize lung function in established cases, the clinical trajectory of the disease remains highly variable and difficult to forecast at the bedside [5, 6]. A new study now offers a method to risk-stratify these patients by analyzing the physiological history of the graft leading up to the clinical diagnosis, providing a clearer window into the expected course of decline.

Stratifying Risk via Pre-Diagnosis Lung Function Trajectory

To better understand the natural history of graft failure, researchers conducted a retrospective cohort study of patients who underwent their first lung transplantation between January 1, 2000, and January 1, 2020. The study identified 293 subjects who met the clinical criteria for a diagnosis of either probable or definite chronic lung allograft dysfunction. This cohort was further categorized by the type of procedure performed, consisting of 162 bilateral orthotopic lung transplant recipients and 131 single orthotopic lung transplant recipients. By focusing on this 20 year window, the authors were able to capture a broad range of clinical outcomes and long term physiological data necessary to model disease progression. The primary methodology involved a granular analysis of the trajectory of forced expiratory volume in one second (FEV1), which is the volume of air an individual can forcibly exhale in the first second of a forced expiration. Specifically, the researchers examined the FEV1 decline during the three months immediately preceding the formal onset of chronic lung allograft dysfunction. Based on this 90 day physiological history, the researchers divided the patients into three distinct cohorts: slow, intermediate, or rapid progressors. This stratification allowed the investigators to determine if the rate of lung function loss occurring before a clinical diagnosis was reached could serve as a reliable predictor for post-diagnosis survival and pulmonary decline in both bilateral and single lung transplant patients.

Post-Diagnosis Physiological Decline in Bilateral and Single Allografts

The stratification of patients based on their pre-diagnosis trajectory revealed distinct physiological outcomes following the formal onset of chronic lung allograft dysfunction. Among the 162 bilateral orthotopic lung transplant recipients, those categorized as intermediate and rapid progressors experienced a more aggressive decline in pulmonary function compared to slow progressors. Specifically, these higher-risk groups demonstrated significantly lower forced expiratory volume in one second (FEV1) at both 3 months and 6 months post-diagnosis. This downward trend was mirrored in their lung volumes, as intermediate and rapid progressors also exhibited significantly lower forced vital capacity (FVC), the total amount of air a patient can exhale after taking the deepest breath possible, at the 3-month and 6-month marks when compared to the slow progression cohort. Similar patterns of physiological deterioration were observed in the 131 single orthotopic lung transplant recipients, though the most pronounced differences were concentrated in the most aggressive phenotype. In this subset, rapid progressors had significantly lower FEV1 at 3 months post-diagnosis and continued to show significantly lower FEV1 at 6 months post-diagnosis relative to their slower-progressing counterparts. The loss of volume was equally significant, as these rapid progressors demonstrated significantly lower forced vital capacity at 3 months and maintained significantly lower forced vital capacity at 6 months post-diagnosis. These findings suggest that the rate of decline in the 90 days prior to a clinical diagnosis serves as a critical physiological signal, allowing clinicians to forecast short-term graft stability and identify patients who may require more intensive monitoring or early therapeutic intervention.

Mortality Risk and Clinical Implications for Patient Management

The physiological decline observed in the months following a diagnosis of chronic lung allograft dysfunction translates directly into a survival disadvantage for those with aggressive pre-diagnosis trajectories. The researchers found that mortality was increased in intermediate and rapid progressors compared with slow progressors, indicating that the velocity of lung function loss before the formal clinical diagnosis serves as a potent indicator of life expectancy. This correlation between early decline and death suggests that the biological processes driving graft failure are already well-established by the time a patient meets the formal diagnostic criteria for chronic lung allograft dysfunction. To further isolate the specific drivers of graft failure, the authors utilized an adjusted Cox proportional hazards regression model (a statistical method used to determine the effect of several variables on the time it takes for a specific event, such as death or graft loss, to occur). This analysis confirmed that rapid pre-diagnosis progression was associated with an increased hazard of chronic lung allograft dysfunction progression in the entire cohort. Furthermore, the model identified that a higher disease stage at the time of diagnosis was also associated with an increased hazard of progression across the study population. These findings establish that both the speed of initial decline and the severity of impairment at presentation are independent and additive risk factors for poor clinical outcomes. Ultimately, the study demonstrates that rates of forced expiratory volume in one second (FEV1) decline in the 3 months before the onset of chronic lung allograft dysfunction predict both disease progression and mortality following the diagnosis in both bilateral and single orthotopic lung transplant recipients. For the practicing clinician, this predictive capacity offers a window for risk stratification at the earliest possible moment. By identifying high-risk phenotypes early, physicians can better enrich future interventional trials with patients most likely to benefit from aggressive therapy, while simultaneously personalizing the intensity of post-transplant monitoring for those at the highest risk of rapid graft failure.

References

1. Fisher AJ, White M, Goudie N, et al. Extracorporeal photopheresis (ECP) in the treatment of chronic lung allograft dysfunction (CLAD): a prospective, multicentre, open-label, randomised controlled trial studying the addition of ECP to standard care in the treatment of bilateral lung transplant patients with CLAD (E-CLAD UK).. BMJ open respiratory research. 2024. doi:10.1136/bmjresp-2023-001995

2. Bos S, Filby AJ, Vos R, Fisher AJ. Effector immune cells in chronic lung allograft dysfunction: A systematic review.. Immunology. 2022. doi:10.1111/imm.13458

3. Royer P, Olivera-Botello G, Koutsokera A, et al. Chronic Lung Allograft Dysfunction: A Systematic Review of Mechanisms.. Transplantation. 2016. doi:10.1097/TP.0000000000001215

4. Pitre T, Gurupatham S, Desai K, et al. Tacrolimus versus cyclosporine immunosuppression in lung transplantation: a systematic review and meta-analysis.. BMJ open respiratory research. 2025. doi:10.1136/bmjresp-2024-002672

5. Huang H, Kato T, Imamura Y, et al. Prophylactic azithromycin for chronic lung allograft dysfunction following lung transplantation: a systematic review and meta-analysis.. Journal of thoracic disease. 2025. doi:10.21037/jtd-2025-365

6. Herck AV, Frick AE, Schaevers V, et al. Azithromycin and early allograft function after lung transplantation: A randomized, controlled trial.. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2019. doi:10.1016/j.healun.2018.12.006