DIAGNOSTIC ACCURACIES OF IGG4/IGG AND IGG4 IN PATIENTS WITH IGG4-RELATED DISEASE: A META-ANALYSIS

초록

Background: Serum IgG4 levels have been widely used as a diagnostic tool for Immunoglobulin G4-related disease (IgG4-RD); however, their sensitivity and specificity are variable, and elevated IgG4 levels are not exclusive to IgG4-RD. To improve diagnostic precision, the IgG4/IgG ratio has been proposed as an additional marker. While studies suggest that both IgG4 and the IgG4/IgG ratio are effective diagnostic markers, their comparative diagnostic performance remains unclear. Objectives: This study aimed to evaluate and compare diagnostic performances of immunoglobulin G4/Immunoglobulin G (IgG4/IgG) and immunoglobulin G4 (IgG4) alone in identifying IgG4-RD. Methods: We conducted a comprehensive systematic review and meta-analysis using data from Medline, Embase, and the Cochrane Library. Two meta-analyses were performed to assess diagnostic accuracies of IgG4/IgG and IgG4 in IgG4-RD patients. Results: Eight studies encompassing 754 IgG4-RD patients and 9,496 non-IgG4-RD controls were included in the analysis. IgG4/IgG demonstrated a sensitivity of 89% and a specificity of 91.6%, accurately detecting IgG4-RD in 89% of cases and correctly identifying non-IgG4-RD in 91.6% of cases. IgG4 alone exhibited a higher sensitivity (94.9%) and a similar specificity (91%), indicating a slightly improved ability to identify IgG4-RD cases. Positive likelihood ratio (PLR) and negative likelihood ratio (NLR) for IgG4/IgG were 7.580 and 0.132, respectively, while IgG4 alone had a PLR of 6.403 and a lower NLR of 0.066, confirming high diagnostic reliability. Diagnostic odds ratio (DOR) was 62.97 for IgG4/IgG compared to 105.6 for IgG4 alone, reflecting enhanced accuracy. Area under the curve (AUC) was 0.949 for IgG4/IgG and 0.986 for IgG4. Q* index was 0.889 for IgG4/IgG and 0.949 for IgG4, further underscoring the diagnostic effectiveness of IgG4 alone. Conclusion: Both IgG4/IgG and IgG4 are highly accurate markers for diagnosing IgG4-RD, with IgG4 alone showing marginally higher sensitivity, DOR, and AUC. This suggests that IgG4 alone may offer a slight advantage as a diagnostic marker for IgG4-RD.