Serum IgG4 and IgG for the diagnosis of autoimmune pancreatitis: A systematic review with meta-analysis

Abstract

The correct diagnosis of autoimmune pancreatitis (AIP) is a clinical challenge. Emerging published data on the accuracy of serum IgG4 and IgG for diagnosing AIP are inconsistent. This study was performed to better elucidate the accuracy of serum IgG4 and IgG in diagnosing AIP. A comprehensive literature search of PubMed, Web of Science, EMBASE, the Cochrane Library and some other databases was conducted before October 2014. The methodological quality of each study was assessed according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) checklist. Random-effects model was used to summarize the sensitivity, specificity and other measures of accuracy. Fifteen studies on IgG4 and 8 studies on IgG were included. The summary estimates for serum IgG4 in distinguishing AIP from the overall controls, pancreatic cancer and ordinary chronic pancreatitis were as follows: sensitivity 0.74 (0.70-0.77), 0.73 (0.69-0.77) and 0.76 (0.72-0.80), respectively, specificity, 0.94 (0.93-0.95), 0.93 (0.91-0.95) and 0.96 (0.95-0.97), respectively. The summary estimates for serum IgG in distinguishing AIP from the overall controls and pancreatic cancer were as follows: sensitivity, 0.53 (0.47-0.59) and 0.51 (0.44-0.57), respectively, specificity, 0.87 (0.85-0.89) and 0.94 (0.91-0.96), respectively. The area under the curve (AUC) of serum IgG in distinguishing AIP from ordinary chronic pancreatitis was 0.657. Both serum IgG4 and IgG have high specificity and relatively low sensitivity for diagnosing AIP. Besides, they are useful for distinguishing AIP from pancreatic cancer and ordinary chronic pancreatitis. To better elucidate the usefulness of serum IgG4 and IgG, further studies are needed.