Lot verification practices in Ontario clinical chemistry laboratories - Results of a patterns-of-practice survey

Abstract

Objectives: Verifying new reagent or calibrator lots is crucial for maintaining consistent test performance. The Institute for Quality Management in Healthcare (IQMH) conducted a patterns-of-practice survey and follow-up case study to collect information on lot verification practices in Ontario.

Methods: The survey had 17 multiple-choice questions and was distributed to 183 licensed laboratories. Participants provided information on materials used and approval/rejection criteria for their lot verification procedures for eight classes of testing systems. The case study provided a set of lot comparison data and was distributed to 132 laboratories. Responses were reviewed by IQMH scientific committees.

Results: Of the 175 laboratories that responded regarding reagent lot verifications, 74% verified all tests, 11% some, and 15% none. Of the 171 laboratories that responded regarding calibrator lot verifications, 39% verified all calibrators, 4% some, and 57% none. Reasons for not performing verifications ranged from difficulty performing parallel testing to high reagent cost. For automated chemistry assays and immunoassays, 23% of laboratories did not include patient-derived materials in reagent lot verifications and 42% included five to six patient materials; 58% of laboratories did not include patient-derived materials in calibrator lot verifications and 23% included five to six patient materials. Different combinations of test-specific rules were used for acceptance criteria. For a failed lot, 98% of laboratories would investigate further and take corrective actions. Forty-three percent of laboratories would accept the new reagent lot in the case study.

Conclusion: Responses to the survey and case study demonstrated variability in lot verification practices among laboratories.

Keywords: CLSI, Clinical and Laboratory Standards Institute; Calibrator; ELISA, enzyme-linked immunosorbent assay; GC, gas chromatography; HPLC, high-performance liquid chromatography; IQMH, Institute for Quality Management in Healthcare; ISO, International Organization for Standardization; LC-MS/MS, liquid chromatography tandem mass spectrometry; Lot number; PT, proficiency testing; QC, quality control; RIA, radioimmunoassay; Reagent; TSH, thyroid-stimulating hormone; Verification.

Fig. 1

The case study.

Fig. 2

Acceptance criteria provided to laboratories as options.

Fig. 3

Summary of responses from participating laboratories about reagent or calibrator lot verification practices according to test system. Results are expressed as a percentage of total responses (n-value shown in the figure) for each test system type from laboratories that performed such testing on-site.

Fig. 4

Summary of the reasons provided for not conducting reagent or calibrator lot verifications. Responses were from 74 laboratories about reagents and 101 laboratories about calibrators and are expressed as a percentage of all responses within the reagent or calibrator category.

Fig. 5

Reasons for not performing reagent or calibrator lot verification for all tests within a methodology category. Results are expressed as a percentage of total responses (n-value shown in the figure) for each test system.

Fig. 6

Participant responses regarding types of material used in reagent or calibrator lot verifications for various analytical systems. Results are expressed as a percentage of total responses (n-value shown in the figure) for each test system.

Fig. 7

Participant responses regarding number of patient or commercial material samples used in reagent or calibrator lot verifications for automated chemistry or immunoassay tests. A) average number of patient material samples used in verification of new reagent or calibrator lots. Results are expressed as a percentage of total responses (169 for reagent, 123 for calibrator). B) average number of commercial material samples used in verification of new reagent or calibrator lots. Results are expressed as a percentage of total responses (172 for reagent, 129 for calibrator).

Fig. 8

Criteria used to determine acceptance or rejection of a new lot number. A total of 592 criteria were provided by 174 laboratories.

Fig. 9

Actions that would be taken when accepting a new lot number that had failed previously-established acceptance criteria. A total of 246 actions were selected by 150 laboratories.