Impact of obstructive sleep apnea on early renal injury biomarkers: A systematic review and meta-analysis.

INTRODUCTION

Obstructive sleep apnea (OSA) is increasingly recognized as a potential contributor to early renal injury. However, whether OSA independently affects kidney function in individuals without known kidney disease remains uncertain. Early identification of subclinical renal damage is crucial for timely intervention.

METHODS

A systematic search was conducted across PubMed, Embase, MEDLINE, Web of Science, Scopus, and Cochrane Library databases from inception to July 7, 2025. Eligible studies included adults without diagnosed chronic kidney disease and reported at least one renal biomarker. Pooled standardized mean differences (SMDs) and 95 % confidence intervals (CIs) were calculated, and correlation coefficients were converted to Fisher z-scores for pooling.

RESULTS

Twenty-six studies with 4302 participants were included. Compared to non-OSA controls, OSA patients exhibited significantly higher levels of urinary microalbumin (UmAlb) (SMD = 0.79), cystatin C (CysC) (SMD = 0.47), urine albumin-to-creatinine ratio (uACR) (SMD = 0.49), neutrophil gelatinase-associated lipocalin (NGAL) (SMD = 0.34), and interleukin-18 (IL-18) (SMD = 2.27) (all P < 0.05). No significant association was observed for KIM-1, β2-MG and L-FABP were only described qualitatively due to insufficient data for pooling. Subgroup analyses showed stronger biomarker elevations in severe OSA and hypertensive individuals. Apnea-hypopnea index (AHI) and hypoxia indices correlated positively with biomarker levels.

CONCLUSIONS

OSA was associated with multiple biomarkers of early kidney damage, even in individuals without underlying kidney disease. The study findings revealed a dose-response relationship between OSA severity and elevated biomarker levels, highlighting hypertension as an important effect modifier. Easily accessible markers such as CysC and UmAlb may aid in the early detection of subclinical kidney damage in OSA populations, thereby supporting earlier risk stratification and intervention strategies.