Introduction: Carcinogen antigen 125 (CA-125) is a glycoprotein antigen, which has shown potentials in predicting peritoneal inflammation. The aim of this study is to determine the value of CA-125 in predicting acute appendicitis (AA).
Methods: This prospective diagnostic accuracy study was conducted on 15 - 70 year-old patients with acute abdominal pain, suspected to AA, referred to emergency department. The serum level of CA-125 was measured for all patients before appendectomy and its screening characteristics in detection of AA case (confirmed by histology findings) were calculated and reported with 95% confidence interval (CI).
Results: 95 patients with the mean age of 31.65 ± 12.9 (15-75) years were studied (54.3% male). Based on the histologic findings, 72 (75.8%) cases were categorized as AA (23 cases as severe). AA and non-AA (NAA) groups were similar regarding the mean age (p = 0.59), mean duration of symptoms (p = 0.08), mean white blood cell (WBC) count (p = 0.37), and mean PMN percentage (p = 0.55). Mean CA-125 level was 16.5 ± 20.0 U/mL in the AA group and 30.5 ± 6.1 U/mL in the NAA group (p = 0.001). Adjustment of analysis based on gender revealed a significant correlation between CA-125 level and diagnosis of AA only in females (34.23 ± 39 U/mL in NAA versus 20.7 ± 26.7 U/mL in AA, p = 0.012). The area under the ROC curve of CA-125 was 0.62 (95%CI: 0.51 to 0.72). Sensitivity, specificity, NPV, PPV, NLR, and PLR of CA-125 in 16.4 U/mL cut off (best point) were 77.8% (95%CI: 66.4 - 86.7), 50.0% (95%CI: 28.2 - 71.8), 83.6% (95%CI: 76.7 - 88.7), and 40.7% (95%CI: 27.4 - 55.6), 0.44 (95%CI 0.2 - 0.8), and 1.56 (95%CI: 1.0 - 2.4), respectively.
Conclusion: Considering the lower levels of CA-125 in patients with AA compared with NAA cases and also weak screening performance characteristics, it seems that it could not be considered as an accurate screening tool in this regard.
Keywords: Appendix; CA-125 antigen; abdominal pain; appendicitis; biomarkers.