Interlaboratory peer comparison programs are quality-assurance activities mandated by the Clinical Laboratory Improvement Amendments of 1988. No commercial program is available currently that was designed for cytology laboratories performing only human papillomavirus (HPV) DNA testing. In this report, the authors provide the results from a self-developed program between 2 cytology laboratories.
Between 4 and 11 SurePath liquid-based cervical cytology samples were selected at each of the 2 participating laboratories each quarter and exchanged without accompanying patient information. Samples were selected to test both positive and negative high-risk HPV DNA results in roughly equivalent numbers. Samples were run with the Hybrid Capture II method using each laboratory's standard procedure. The result obtained was compared with the originating laboratory's result. Correlation was compared on an ongoing basis as a method to assess analytic performance.
Over a 3-year period, 12 exchanges took place, constituting 113 total specimens. Overall, there were 9 exchanges of 76 specimens that had 100% correlation, and 3 exchanges in which 4 of 37 specimens had discordant results. Overall, this represented a 97% correlation (109 of 113 specimens) of results between laboratories. All 4 discordant cases were reported as negative by the original laboratory and positive by the exchange laboratory (2 in each direction).
The interlaboratory peer comparison result of 97% concordance demonstrated excellent analytic agreement between the HPV DNA-detection procedures of each laboratory. All discordant cases were "negative to positive" and were distributed equally by originating laboratory. The procedure was easily set up and provided assurance to each laboratory of ongoing performance for the detection of the HPV DNA analyte.