Pulmonary Symptoms and Psychological Distress as Correlates and Mediators of Quality of Life in Lung Transplant Recipients: A Cross-Sectional Study.

Background: Lung transplant recipients often live for years with residual respiratory symptoms and psychological distress, but the pathways through which these factors affect quality of life (QoL) are not fully understood. We examined how transplant-specific pulmonary symptom burden and psychological distress relate to generic and transplant-specific QoL in long-term lung transplant recipients. Methods: In this cross-sectional study, 76 adult lung transplant recipients from a single center completed the Lung Transplant Quality of Life (LT-QoL) questionnaire, EQ-5D-5L, SF-36, St George's Respiratory Questionnaire (SGRQ), and Hospital Anxiety and Depression Scale (HADS). A composite psychological distress index was derived from HADS-Anxiety, HADS-Depression, and the LT-QoL Anxiety/Depression and Health Distress subscales. Associations were examined using Pearson correlations, hierarchical linear regression (adjusting for age, sex, and time since transplant), and statistical mediation models examining psychological distress as a potential mediator between pulmonary symptoms and QoL outcomes. Results: Pulmonary symptom burden (LT-QoL Pulmonary Symptoms) was in the low-moderate range yet showed robust correlations with poorer generic, transplant-specific, and respiratory-specific QoL (|r| up to 0.82). The psychological distress index demonstrated good internal consistency (α = 0.84) and was strongly associated with worse EQ-5D, SF-36, and LT-QoL General QoL scores. In regression models, pulmonary symptoms and psychological distress independently predicted SF-36 overall QoL (R2 = 0.55), whereas psychological distress was the stronger predictor of the EQ-5D Index Value. Statistical mediation analyses were consistent with partial mediation of the association between pulmonary symptoms and SF-36 and the EQ-5D Index Value, while effects on the EQ-VAS and LT-QoL General QoL were largely direct. Conclusions: Even modest pulmonary symptom burden and psychological distress are tightly linked to QoL years after lung transplantation. Routine follow-up should include brief assessment of both domains, and integrated care models that combine optimization of pulmonary status with targeted psychological support may be needed to preserve long-term QoL in lung transplant recipients.