Role of C5aR2 in prognosis of patients with acute respiratory distress syndrome through negative modulation of C5a: A prospective observational study.

Summary

In a prospective cohort of 64 ARDS patients, the C5a/C5aR2 ratio outperformed individual markers in predicting poor outcomes (AUC 0.707; specificity 78.1%). Higher C5aR2 levels were associated with recovery (OR 0.225), while a higher C5a/C5aR2 ratio predicted non-recovery (OR 3.281). Steroid therapy correlated with better recovery among patients with a high C5a/C5aR2 ratio.

Key Findings

• C5a/C5aR2 ratio showed the best discrimination for poor prognosis (AUC 0.707; specificity 78.1%) compared with C5aR2 (AUC 0.699) and C5a (AUC 0.511).
• Higher C5aR2 levels were associated with better recovery (OR 0.225; p=0.009), while a higher C5a/C5aR2 ratio predicted non-recovery (OR 3.281; p=0.036).
• Corticosteroid use was associated with better recovery among patients with a high C5a/C5aR2 ratio (OR 0.104; p=0.007).

Clinical Implications

Consider complement profiling in moderate-to-severe ARDS to refine prognosis; patients with high C5a/C5aR2 ratios may particularly benefit from corticosteroids, pending validation.

Limitations

• Single-year, relatively small sample size (n=64) limits generalizability
• Potential residual confounding; external validation cohorts are lacking

Future Directions

Validate C5aR2 and the C5a/C5aR2 ratio in larger, multicenter cohorts; test biomarker-guided corticosteroid strategies in randomized trials.