Clinical phenotypes and prognosis of IgG4-related diseases accompanied by deteriorated kidney function: a retrospective study

Introduction IgG4-related disease (IgG4-RD) is a multiorgan autoimmune disorder that causes irreversible injury. Deteriorated kidney functions are common but easily ignored complications associated with IgG4-RD. Yet the clinical manifestations and prognosis of this specific entity have not been fully illustrated. Method Three hundred fifty patients with IgG4-RD were retrospectively enrolled and divided into 119 IgG4-RD with chronic kidney disease (IgG4-RD CKD+) and 231 IgG4-RD without CKD (IgG4-RD CKD-). Demographic clinical and laboratory characteristics and survival of two cohorts were compared using restricted cubic splines, logistic and Cox regression, and Kaplan-Meier analysis. A nomogram was generated for calculating the probability of CKD in IgG4-RD. Results The spectrum of organ involvement was different between IgG4-RD CKD+ and CKD- cohorts ( p <0.001). Lung (26.89%) and retroperitoneum (18.49%) involvement were more common in the IgG4-RD CKD+ cohort. Increased serum potassium and phosphorus, reduced calcium levels, and hypocomplementemia (all p <0.05) were observed in IgG4-RD CKD+. Restricted cubic splines revealed a U-shaped plot regarding associations between serum potassium and CKD. Kaplan-Meier analysis demonstrated significantly lower long-term survival rates in IgG4-RD patients with kidney function at CKD stages 4–5. Cox regression revealed declined kidney functions (G4 HR 6.537 (95% CI: 1.134–37.675)) associated with increased all-cause mortality in IgG4-RD patients. A nomogram was constructed to predict CKD in IgG4-RD promptly with a discrimination (C-index) of 0.846. Conclusions CKD in IgG4-RD was associated with poor outcomes and electrolyte disturbances. Patients with IgG4-RD should be aware of possible deterioration in kidney function. The nomogram proposed would help to identify the subtle possibility of CKD in IgG4-RD. Key points • IgG4-related diseases with deteriorated kidney function have specific clinical and laboratory characteristics. • It is crucial to recognize and address the negative impact of deteriorating kidney function in IgG4-related diseases to prevent further harm. • The nomogram proposed would help to identify subtle kidney involvement by evaluating the possibility of CKD in IgG4-related diseases.