How Good Is EUS to Detect Pancreatic Insulinomas? A Meta-Analysis and Systematic Review

Abstract

Background: The published data on accuracy of Endoscopic Ultrasound to detect pancreatic insulinomas (PI) has been varied. Detection of PI is critical from a therapeutic stand point. Aim: To evaluate the accuracy of EUS in detecting PI. Method: Study Selection Criteria: Only EUS studies confirmed by surgery or appropriate follow-up were selected. Only studies from which a 2 X 2 table could be constructed for true positive, false negative, false positive and true negative values were included. Data collection & extraction: Articles were searched in Medline, Pubmed, Ovid journals, Cumulative index for nursing & allied health literature, International pharmaceutical abstracts, old Medline, Medline nonindexed citations, and Cochrane Central Register of Controlled Trials & Database of Systematic Reviews. Two reviewers independently searched and extracted data. The differences were resolved by mutual agreement. 2 X 2 tables were constructed with the data extracted from each study. Statistical Method: Meta-analysis for the accuracy of EUS was analyzed by calculating pooled estimates of sensitivity, specificity, likelihood ratios, and diagnostic odds ratio. Pooling was conducted by both Mantel-Haenszel method (fixed effects model) and by the DerSimonian Laird method (random effects model). The heterogeneity among studies was tested using Cochran's Q test based upon inverse variance weights. Results: Initial search identified 2610 reference articles, of these 130 relevant articles were selected and reviewed. Data was extracted from 9 studies (N= 242) which met the inclusion criteria. Pooled sensitivity of EUS to detect PI was 87.5% (95% CI: 81.2 - 92.3). EUS had a pooled specificity of 97.4% (95% CI: 90.8 - 99.7). The positive likelihood ratio of EUS was 8.2 (95% CI: 3.7 - 18.3) and negative likelihood ratio was 0.17 (95% CI: 0.12 - 0.26). The diagnostic odds ratio, the odds of having anatomic PI in positive as compared to negative EUS studies was 67.6 (95% CI: 22.7 - 200.9). All the pooled estimates calculated by fixed and random effect models were similar. SROC curves showed an area under the curve of 0.94. Egger bias indicator for publication bias gave a value of -0.05 (95% CI = -4.13 to 4.04, p = 0.98), indicating no publication bias. The p for chi-squared heterogeneity for all the pooled accuracy estimates was > 0.10. Conclusions: EUS has excellent sensitivity and specificity to detect PI. EUS should be strongly considered for evaluation of PNT.