Diagnostic accuracy and prognostic value of urinary soluble CD163 in lupus nephritis: a systematic review and diagnostic meta-analysis

Lupus nephritis (LN) is a major cause of morbidity and progression to end-stage renal disease (ESRD) in patients with systemic lupus erythematosus (SLE). Current biomarkers, including proteinuria and serological markers, have limited accuracy for detecting active renal inflammation and often fail to reflect intrarenal immune activity. Noninvasive biomarkers are therefore urgently needed. To evaluate the diagnostic accuracy and prognostic value of urinary soluble CD163 (uCD163) in patients with LN. We conducted a systematic review and diagnostic meta-analysis in multiple databases, including PubMed, Embase, and Cochrane to evaluate the performance of uCD163 in detecting active LN. Pooled sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence intervals (CIs) were estimated using random-effects models, and overall diagnostic performance was assessed using summary receiver operating characteristic (SROC) analysis to obtain a pooled area under the curve (AUC). All statistical analyses were performed using R. We included eight studies with 1,110 participants. uCD163 demonstrated favorable pooled diagnostic performance, with a pooled sensitivity of 0.89 (95% CI: 0.79–0.94) and specificity of 0.91 (95% CI: 0.81–0.96). The SROC analysis yielded an AUC of 0.93. The pooled DOR was 63.37 (95% CI: 14.25–281.75; p < 0.0001). In addition, substantial heterogeneity was observed (I² = 85%), and Deeks’ funnel plot asymmetry test was borderline at the prespecified threshold (t = -1.95, p = 0.0995), indicating that publication bias or small-study effects cannot be excluded. uCD163 demonstrated favorable diagnostic performance for detecting active lupus nephritis, with high pooled sensitivity and specificity. Despite substantial between-study heterogeneity and the overall low certainty of evidence, these findings suggest that uCD163 may serve as a useful complementary noninvasive biomarker for assessing disease activity.