A-282 Analysis of Recheck and Revision Rates Across the Life Cycle of High Volume Chemistry Analyzers: Informing Lab Stewardship and Asset Management

Abstract

Monitoring patient retesting and result corrections, or revision rates, following quality control (QC) failures in a high-volume clinical chemistry laboratory helps inform QC practices. Our laboratory uses rule-based statistical QC (via mean and standard deviation) to detect deviations from stable operation. Patient rechecks are performed systematically after QC failures to determine if results need to be corrected/revised based on each test’s unique revision criteria. Criteria for revising results are established for each test based on total allowable error and reflect clinically significant deviations in test results. The aim of this study was to calculate the recheck and revision rates over the life of two sets of chemistry analyzers. A retrospective review of patient recheck and revision events was performed for the Central Clinical Laboratory (Mayo Clinic Rochester) from 2015–2025. The laboratory performed approximately 110 tests on combination chemistry/immunoassay lines replacing cobas6000 (two combination c701, c502, c602, e602 lines) equipment with cobas8000 (three combination c701, e801 lines) platforms between October 28, 2019 to February 6, 2020 (Roche Diagnostics, Indianapolis, IN). Average annual test volume was determined from the lab information system. Recheck rates were calculated as the proportion of samples retested following QC failure relative to total testing volume. Revision rates were calculated as the proportion of repeated results exceeding revision limits relative to total patient rechecks. These metrics were tallied annually and subsequently averaged across five years to compare c6000 and c8000 analyzer performance during the first two years of service (new) and the final two years of service (old). 2-tailed student t-test was calculated with p<0.05 considered significant. The c6000 instruments were in service 2015-2019 with average annual test volume=3.1M and c8000 instruments from 2020-2025 with 3.4M average annual volume excluding 2020. During these time periods c6000 had average (standard deviation) annual recheck rate of 0.21(0.08) % and c8000 = 0.34(0.03)% (p=0.01). C6000 increased from 0.13% in 2015 to 0.33% in 2019 while c8000 varied with no clear pattern over time. Revision rates for c6000 were 8.5(2.0)% and c8000 were 5.1(1.1)% (p=0.01). The first two years of service (new) for c6000 compared to its last 2 years of service (old) had recheck rates of new=0.14(0.01)% and old=0.30(0.06)% (p=0.06) and revision rates of new=8.3(1.5)% and old=9.1(3.4)% (p=0.8). The c8000 had recheck rates of new=0.33(0.02)% and old=0.33(0.05)% (p=0.9) and revision rates of new=5.0(0.2)% and old=5.7(1.9)% (p=0.7). Recheck rates increased over the life of c6000 instruments and remained elevated and steady during the life of c8000 instruments. Revision rates decreased for c8000 instruments compared to c6000 and did not correlate with instrument age. This pattern may reflect increased testing volume, test menu complexity, and operational workflow changes associated with expansion from two to three chemistry lines. Monitoring recheck and revision rate trends longitudinally may provide an objective measure to support proactive maintenance strategies and inform capital replacement planning in high-volume laboratories.