A cross‐lagged analysis of the relationship between quality of life and kidney function in CKD patients

Background: Chronic kidney disease (CKD) significantly impacts patient well-being, with declining glomerular filtration rate (eGFR) often leading to worsening quality of life (QoL). However, the directionality of the eGFR–QoL relationship remains unclear due to limitations of prior cross-sectional and longitudinal studies. Methods: This study applied cross-lagged analysis to investigate the reciprocal relationship between eGFR and QoL (measured using SF-36 Physical and Mental Component Scores [PCS and MCS]) over 36 months in 422 CKD patients recruited from nephrology units in Southern Italy. Generalized Method of Moments (GMM) models tested two hypotheses: (1) PCS as a determinant of MCS, or vice versa; and (2) eGFR as a determinant of MCS/PCS, or vice versa. Results: Cross-lagged analysis confirmed that lower eGFR significantly predicted declines in both PCS and MCS in subsequent visits (p <.05). At the same time, the reverse relationship (QoL affecting eGFR) was not statistically significant. Multivariable models, adjusting for potential confounders including demographic factors, comorbidities, and socioeconomic status, confirmed these findings. Conclusion: Kidney function decline leads to worsening QoL, whereas deterioration in QoL does not impact eGFR decline. These findings support prioritising interventions that slow the progression of CKD as a means to preserve quality of life. This study highlights the utility of cross-lagged analysis in nephrology research and underscores the importance of early chronic kidney disease (CKD) management to maintain patient well-being.