Lower frequency of certain nonconformities against ISO/IEC 17025 after many year accreditation

Abstract

Background: It is predictable that the laboratories with many years of accreditation should get lower amount of nonconformities than those of the new ones. The objectives of the study are to find the differences in characteristics and nonconformities among ISO/IEC 17025 accredited laboratories undergoing on-site assessment in 2015 and verify the above prediction.

Materials and methods: A cross-sectional study of the characteristics and the nonconformities from 2015 assessment of 134 laboratories were compared between the laboratories with 6 or more years or at least 3 cycles of accreditation and the ones with shorter accreditation year. Statistical analyses were done by using Stata-intercooled version 6.

Results: There were 1,459 total nonconformities, 572 (39%) were those against management requirements and 887 (61%) were those from technical ones. Longer and new accredited laboratories shared similar basic characteristics. Longer accredited laboratories got lower total nonconformities (mean±SD; 9.1±4.8 vs 12.7±9.0: t-test=2.89, p=0.003), and lower technical nonconformities (mean±SD; 5.0±3.1 vs 8.3±6.9: t-test=3.57, p<0.001). The proportion of longer accredited laboratories was lower on nonconformities against clause 5.6 Measurement traceability (14/87 vs 28/67, Chi square=5.060, p=0.024) and the ones against clause 5.9 Assuring quality of test results (27/67 vs 44/67, Chi-square=6.450, p=0.011) than those of the new accredited laboratories.

Conclusion: This study demonstrated that many year accreditations may enable the accredited laboratories to comply with the requirements more effectively. Lower proportions of the longer accredited laboratories had lower certain nonconformities on clause 5.6 Measurement traceability and 5.9 Assuring quality of test results.