Verification of Access OV Monitor (Cancer Antigen 125) Assay on Beckman Coulter Unicel DXI 800

Abstract

Abstract CA 125 levels are increased in ovarian carcinoma and other benign and malignant conditions. Levels are used to monitor response to therapy and disease progression. The objective of this study was to assess the analytical performance of the Access OV Monitor assay on the Beckman Coulter DXI. CA 125 was quantitatively determined on Beckman Coulter DXI following CLSI guidelines. Performance was evaluated for linearity, sensitivity, reference range, and precision. Within-run and between-run precisions were assessed by analyzing QC material at low and high concentrations. Accuracy was assessed by comparing 147 consecutive values with the previously established Siemens ADVIA Centaur XP. Antigen levels were classified as positive or negative based on the upper limit of the reference range to assess concordance between the two analyzers. The analytic measurement range was linear between 0.5 and 5,000 U/mL with a slope of 0.983 and intercept of 0.46. The reference range was 0 to 35 U/mL. Within-run CVs were 3.4% and 3.5% at low (53.81 U/mL) and high (392.78 U/mL) levels, respectively. Between-run CVs were 3.46% and 3.0% at low and high levels, respectively. The comparison results showed slope was 1.319 with an intercept of 12.61 and correlation coefficient of 0.9868 (Deming regression). The mean bias was 57.36 (33.98%). The correlation coefficient was 0.9633 and 0.9833 when CA 125 was negative and positive, respectively. The bias was 3.51 (25.73%) and 142.12 (34.41%) when CA 125 was negative and positive, respectively. The agreement was 94% (n = 138) and disagreement was 6% (n = 9). In conclusion, CA 125 on Beckman Coulter DXI has good linearity and precision and shows positive bias. There is good correlation and agreement between the two methods. Clinicians can reliably use the assay but should consider the potential bias when interpreting values near the upper end of the reference range.