Method comparison studies for prostate specific antigen and unconjugated estriol immunoassays.
OBJECTIVE: Method comparison studies were performed in order to move a semi-automated prostate specific antigen (PSA) immunoassay and a manual unconjugated estriol (uE3) immunoassay to an automated chemistry immunoassay analyzer. The results of the two method comparison studies are compared. DESIGN: Serum samples collected on patients with physician orders for PSA or uE3 were assayed by both methods. PSA samples were assayed on a Hybritech Tandem Photon ERA and on two Beckman Coulter Access instruments. UE3 samples were assayed by RIA and on two Beckman Coulter Access instruments. Linear regression analysis was performed on both sets of data and within-run precision and dilution studies were performed on the PSA Access method. SETTING: Clinical chemistry laboratory, West Virginia University Hospitals Inc, Morgantown WV. RESULTS: PSA linear regression analysis for the two methods (ERA and Access 1) were y = 1.0008x + 0.0393, r = 0.9976, SE = 0.1319, n = 37 and (ERA and Access 2), y = 1.0019x + 0.0486, r = 0.9964, SE = 0.1632, n = 37. Within-run precision studies for both Access instruments produced acceptable coefficient variations and dilution study results were in PSA reportable range. uE3 linear regression analysis for the two methods (RIA and Access 1) were y = 1.4105x - 0.3741, r = 0.8696, SE = 0.8330, n = 33 and (RIA and Access 2) were y = 1.315x - 0.2292, r = 0.8643, SE = 0.7964, n = 33. CONCLUSION: The results of the method comparison studies for PSA were acceptable and the automated PSA immunoassay method was adopted. The results of the uE3 comparison studies did not show good correlation; the automated method was not adopted.