American Pathologists Proficiency Testing Program Research Articles

Reporting and Establishment of Reference Intervals for Antiphospholipid Antibody Immunoassays: A Survey of Participants in the College of American Pathologists Proficiency Testing Program.

Misdiagnosis of antiphospholipid syndrome can occur owing to the wide diversity of antiphospholipid (aPL) assays and a lack of international calibrators and harmonized reference intervals. To assess laboratory practices regarding reporting and establishing reference intervals for immunoglobulin (Ig) G/IgM anti-cardiolipin (aCL) and anti-beta-2 glycoprotein I (anti-β2GPI) assays. Supplemental questions related to reporting and establishing reference ranges for aPL assays were sent as part of the Antiphospholipid Antibody (ACL)-B 2019 College of American Pathologists (CAP) proficiency testing survey. The response rate and methods assessment details were determined, as well as qualitative and quantitative results for 3 test samples. The number of participants reporting results for IgG aCL (n = 489), IgM aCL (n = 476), IgG anti-β2GPI (n = 354), and IgM anti-β2GPI (n = 331) varied by antibody type. The enzyme-linked immunosorbent assay (ELISA) (up to 58.6%, 260 of 444) was the most used method; others included multiplex (from 18.9% to 23.9%), fluorescence enzyme immunoassay (14.4%-17.6%), and chemiluminescence immunoassay (6.5%-9.0%). More respondents reported quantitative than qualitative results and manufacturer cutoff ranges were used by 92.9% and 94.2% of respondents for aCL and anti-β2GPI, respectively. Despite variation in the use of semiquantitative ranges, qualitative negative/positive reporting of the test samples achieved almost 100% consensus. Qualitative consensus was met in contrast to the wide range of quantitative results obtained for each analyte across different kits. ELISA remains the most used method for detecting aPL antibodies with most laboratories reporting quantitative results based on manufacturers' suggested reference ranges. The categorization of quantitative results as equivocal, weak positive, or positive for responders using kits from the same manufacturer was variable.

Significant Variability in the Identification and Reporting of Band Neutrophils by Participants Enrolled in the College of American Pathologists Proficiency Testing Program: Time for a Change.

Increased band neutrophils in blood smear differential counts ("bandemia") are entrenched in medicine as a flag for sepsis. However, laboratory hematology experts have long advocated for discontinuation of reporting bands separately from segmented neutrophils because of poor sensitivity and specificity, poor interobserver agreement, and availability of alternative biomarkers for sepsis. To describe band neutrophil reporting practices and reproducibility of band classification among laboratories participating in the College of American Pathologists (CAP) proficiency testing (PT) program. A survey questionnaire was distributed to hematology PT participants. A subsequent morphologic challenge included 12 preselected cell identifications of segmented neutrophils, bands, and metamyelocytes, and a 100-cell manual differential count of a digitally scanned blood smear. Among laboratories that reported manual differentials, most respondents reported bands (4554 of 5268; 86.4%). Only 3222 of 4412 respondents (73.0%) provided band reference ranges. Though participants classified "easy" band neutrophils well (78.0%-98.3%), categorization of cell identifications for "moderate" and "difficult" bands was poor (3.1%-39.0% of laboratories), with classification instead as segmented neutrophils. This pattern was seen regardless of laboratory demographic characteristics. Marked variability in band counts was observed on the 100-cell differential count for both CAP PT participants and CAP Hematology and Clinical Microscopy Committee (HCMC) members (coefficients of variation, 55.8% and 32.9%, respectively). Variability was significantly improved when segmented and band neutrophils were grouped together (coefficients of variation, 6.2% and 5.0%, respectively). Most CAP PT-participating laboratories report band counts, many without reference ranges. The survey confirms significant interlaboratory variability of band enumeration when bands are separately identified from segmented neutrophils. This study reaffirms the CAP Hematology and Clinical Microscopy Committee's strong recommendation to group segmented and band neutrophils together in manual differential counts.

Interlaboratory Agreement of Anti-Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Serologic Assays in the Expedited College of American Pathologists Proficiency Testing Program.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a recently emerged, currently pandemic virus, and the etiologic agent of coronavirus disease 2019 (COVID-19). Clinical testing for antibodies to SARS-CoV-2 has rapidly become widespread, but data regarding the interlaboratory performance of these serologic assays are limited. To describe the development and initial results of the College of American Pathologists (CAP) SARS-CoV-2 Serology Survey. Members from the CAP Microbiology and Diagnostic Immunology and Flow Cytometry Committees formed a working group to support development of a new proficiency testing survey for anti-SARS-CoV-2 antibody assays. Supplemental questions in the survey assessed the state of SARS-CoV-2 serologic testing among participating laboratories as of July 2020. Results were analyzed for agreement by immunoglobulin (Ig) isotype tested, assay manufacturer, and methodology. A total of 4125 qualitative results were received from 1110 laboratories participating in the first survey. Qualitative agreement for assays measuring anti-SARS-CoV-2 total antibodies or IgG was greater than 90% for all 3 samples in the survey. Qualitative agreement for IgM and IgA for the negative sample was greater than 95%, but lacked consensus for the other 2 samples. These initial data suggest overall excellent agreement and comparable performance for most qualitative anti-SARS-CoV-2 IgG and total antibody assays across all participating clinical laboratories, regardless of specific target antigen or assay methodology.

External Quality Assurance of Platelet Function Assays: Results of the College of American Pathologists Proficiency Testing Program.

The College of American Pathologists (CAP) developed proficiency testing for platelet function assays by using blood collected by the participant added to challenge tubes containing either saline (normal) or tirofiban (abnormal). To analyze platelet function proficiency testing for Platelet Function Analyzer PFA-100, platelet aggregation, PlateletWorks, and PlateletMapping. Proficiency testing data from 2012-2016 were analyzed. For PFA-100, a total of 1200 laboratories participated; the coefficient variation (CV) of cartridge closure times was 22% (saline); 44,952 of 45,616 survey responses (99%) provided an interpretation, and 42,934 of 44,952 (96%) were correct. For optical platelet aggregation, 190 laboratories participated; the CV was 17% (saline), 7444 of 7813 survey responses (95%) provided an interpretation, and 7015 of 7444 (94%) were correct. For PlateletWorks, 60 laboratories participated; the CV was 3% to 11% (saline); 2412 of 2454 survey responses (98%) provided an interpretation, and 1207 of 1276 (95%) were correct for adenosine diphosphate (ADP) and 936 of 1136 (82%) for collagen. For PlateletMapping, 200 laboratories participated. For ADP, 1128 of 2697 survey responses (42%) provided an interpretation, but only 927 of 1128 (82%) were correct. For arachidonic acid, 1139 of 2604 survey responses (44%) provided an interpretation and 964 of 1139 (85%) were correct. CAP is the first to provide proficiency testing for platelet aggregation, PlateletWorks, and PlateletMapping. Platelet aggregation, PFA-100, and PlateletWorks using ADP as an agonist performed well with more than 90% of laboratories providing an interpretation and a similar number providing correct results. PlateletWorks using collagen and PlateletMapping showed worse interpretive accuracy than the other methods.

The Power of Proficiency Testing: Unraveling Single-Nucleotide Polymorphism Interference, With Potential Impact on Clinical Testing of Spinocerebellar Ataxia Type 3

The College of American Pathologists proficiency testing program has been instrumental in identifying problems in clinical testing. To describe how this program was used to identify a single-nucleotide polymorphism that affects clinical testing for spinocerebellar ataxia type 3. A proficiency testing sample with discordant results for spinocerebellar ataxia type 3 analysis was further evaluated by targeted Sanger sequencing and genotype polymerase chain reaction using multiple DNA polymerases. Of 28 laboratories responding in the spinocerebellar ataxia type 3 Proficiency Survey, 18 reported an incorrect homozygous result and 10 reported the expected heterozygous result. A heterozygous single-nucleotide polymorphism complementary to the 3' end of a published forward primer was identified in the proficiency testing sample, which may have led to allele dropout. However, this primer was used by only 3 of 18 laboratories (16%) reporting a homozygous result. A new forward primer of identical sequence, except for the 3' end being complementary to the single-nucleotide polymorphism, showed the expected heterozygous pattern. The possibility of DNA polymerase 3'-5' exonuclease activity contributing to allele dropout was investigated by testing 9 additional polymerases with and without exonuclease activity. No clear pattern emerged, but enzymes with and without 3'-5' exonuclease activity yielded both homozygous and expected heterozygous results with the published forward primer. Proactive systematic primer sequence checking is recommended because single-nucleotide polymorphism interference may result in allele dropout and impact clinical testing. Allele dropout is also influenced by other factors, including DNA polymerase exonuclease activity.

Abstract 2206: A new sensitive, accurate liquid chromatography-tandem mass spectrometry (LC-MS-MS) method to measure circulating estrogens, androgens, and progesterone in postmenopausal and premenopausal women

Abstract Endogenous steroid hormones play a critical role in the etiology of breast cancer. However, the interrelationships among estrogens, androgens, and progesterone in determining risk are not well understood. Relative strengths of associations, independent and joint effects, differential effects for tumor subtypes, and effect modification by lifestyle and genetic profile remain unclear. A major reason is the limited accuracy, specificity, and sensitivity of many steroid hormone assays, especially at the low circulating hormone concentrations characteristic of postmenopausal women. CDC developed a new sensitive, accurate isotope dilution LC-MS/MS method capable of measuring eight important steroid hormones in 200 µL of female serum. The method uses sequential liquid-liquid extractions for isolation of estradiol (E2), estrone (E1), estrone sulfate (E1S), testosterone (TT), androstenedione (A), dehydroepiandrosterone sulfate (DHEAS), progesterone (P), and 17-hydroxyprogesterone (17-OHP) without derivatization or hydrolysis. Chromatographic separation of the steroids is carried out using a phenyl-hexyl HPLC column and a gradient of methanol and methanol:water. Scheduled selected reaction monitoring by electrospray ionization in the positive and negative ion modes is applied to quantify the analytes. Two mass transitions, each specific to the fragmentation of the analyte, are monitored for each analyte: quantitation ion (QI) and confirmation ion (CI). The QI to CI ratios are used as criteria to identify possible interferences. The method is able to measure each steroid in nearly all postmenopausal women as well as premenopausal women. Limits of detection in serum-based materials are: E2 1.72 pg/mL, E1 0.13 ng/dL, E1S 2.04 pg/mL, TT 0.57 ng/dL, A 0.82 ng/dL, DHEAS 0.22 µg/dL, P 0.86 ng/dL, and 17-OHP 0.41 ng/dL. Precision, expressed as coefficients of variation and evaluated at three levels for each analyte, ranged from 1.2 to 9.9%. Average bias, a measure of accuracy, ranged from -0.3 to 8.8%. The method is certified through the CDC Hormone Standardization Program for estradiol and testosterone and meets the requirements of the College of American Pathologists Proficiency Testing Program for androgens and progesterone. This new, highly specific and sensitive method demonstrates high accuracy and precision while requiring small amounts of specimens. It can assay up to 140 samples at once. Thus, the method is suitable for large epidemiologic studies investigating the hormonal etiology of breast, endometrial, and ovarian cancer. Citation Format: Lumi Duke, Paul H. Kim, Julianne Cook Botelho, Regina G. Ziegler, Hubert Vesper. A new sensitive, accurate liquid chromatography-tandem mass spectrometry (LC-MS-MS) method to measure circulating estrogens, androgens, and progesterone in postmenopausal and premenopausal women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2206.

Worldwide Frequency of Commonly Detected EGFR Mutations.

- Recurrent epidermal growth factor receptor ( EGFR) mutations are seen in a subset of pulmonary adenocarcinomas. These mutations are targeted by EGFR inhibitors and are a biomarker for response to EGFR inhibitor therapies. Initial data have indicated an increased frequency of activating EGFR mutations in nonsmoking Asian females. However, there are very few studies of global scope that address the question of mutation distribution across the population of lung cancer. - To determine the frequency of EGFR mutations in exons 18 through 21 detected in clinical laboratories participating in the College of American Pathologists proficiency testing program for EGFR in calendar year 2013. - We reviewed the surveys from 170 clinical laboratories from 20 countries that participated in the College of American Pathologists EGFR proficiency testing program. The proficiency testing includes questions regarding the total numbers of tests performed at each common mutation site, including both activating and resistance mutations, and their frequency. Countries were grouped into regional groups in order to assess frequency of mutation by type, and to indirectly assess ethnic differences in mutation frequencies. - Among the treatment-sensitive activating mutations, the most common are exon 19 mutations (n = 10 802 of 136 533 cases; 7.9% of total cases tested) and the exon 21 L858R mutation (n = 10 351 of 136 533 cases; 7.6% of total cases tested) and the least common are exon 20 mutations (n = 466 of 136 533 cases; 0.3% of total cases tested). The T790M mutation in exon 20 is the more common resistance mutation (n = 1010 of 136 533 cases; 0.7% of all cases tested). The highest activating mutation frequency is seen in southern Asia (n = 4260 of 9337 cases; 46%) and the lowest activating mutation frequencies are in South and North America (n = 113 of 1439 cases and 7926 of 86 654 cases; 8% and 9%, respectively). - Our data confirm that activating EGFR mutations are more common in southern Asia and that the distribution of activating EGFR mutations varies significantly across the regions. Similarly, the frequency and distribution of resistance mutations also show significant variation when comparing southern Asia with other regions.

Reporting Results of Molecular Tests: A Retrospective Examination of BRAF Mutation Reporting.

- With enormous growth in the field of molecular pathology, the reporting of results gleaned from this testing is essential to guide patient care. - To examine molecular reports from laboratories participating in proficiency testing for required elements to convey molecular laboratory test results to clinicians and patients. - Molecular laboratories participating in the College of American Pathologists (CAP) proficiency testing program for BRAF mutation analysis were solicited to submit examples of final reports from 2 separate proficiency testing reporting cycles. Reports were reviewed for the presence or absence of relevant components. - A total of 107 evaluable reports were received (57 demonstrating a positive result for the BRAF V600E mutation and 50 negative). Methods for BRAF testing varied, with 95% (102 of 107) of reports adequately describing their assay methods and 87% (93 of 107) of reports adequately describing the target(s) of their assays. Information on the analytic sensitivity of the assay was present in 74% (79 of 107) of reports and 83% (89 of 107) reported at least 1 assay limitation, though only 34% (36 of 107) reported on variants not detected by their assays. Analytic and clinical interpretive comments were included in 99% (106 of 107) and 90% (96 of 107) of reports, respectively. Of participants that perform a laboratory-developed test, 88% (88 of 100) included language addressing the development of the assay. - Laboratories participating in BRAF proficiency testing through the CAP are including most of the required reporting elements to unambiguously convey molecular results. Laboratories should continue to strive to report these results in a concise and comprehensive manner.

Variability in Testing for Antineutrophil Cytoplasmic Antibodies: A Survey of Participants in the College of American Pathologists Proficiency Testing Program.

-Variability in testing for antineutrophil cytoplasmic antibodies (ANCAs) contributes to confusion and controversy related to testing for vasculitis and other ANCA-associated diseases. -To survey laboratory testing practices regarding ANCA testing and to investigate differences in testing algorithms. -Supplemental questions were sent to the 333 laboratories participating in the College of American Pathologists proficiency testing program for ANCA as part of the Special Immunology S2 Survey. -A total of 315 laboratories submitted responses to the supplemental questions. Only 88 of 315 participants (28%) reported using a combination of indirect immunofluorescence (IFA) and enzyme immunoassay (EIA) techniques as recommended by current guidelines, with a few additional labs using IFA and multiplex bead assay as an acceptable alternative to EIA. Other labs reported using only IFA, EIA, or multiplex bead assays. -A wide variety of testing algorithms are in use for ANCA testing despite evidence to suggest that a combination of IFA and EIA testing provides the most comprehensive information. Laboratories should inform clinicians clearly about testing practices and utility of testing in specific disease states.

External Quality Assurance of Fibrinogen Assays Using Normal Plasma: Results of the 2008 College of American Pathologists Proficiency Testing Program in Coagulation

Proper diagnosis and therapy of fibrinogen deficiency requires high-quality fibrinogen assays. To assess the interlaboratory bias, precision, and grading of fibrinogen assays used by laboratories participating in the United States College of American Pathologists proficiency testing program in coagulation. Two identical vials of normal plasma were sent to more than 3500 laboratories. Participants measured fibrinogen levels using local methods. Fifty different fibrinogen methods were evaluated. All-method bias was 8.3% (range of method-specific biases, 0.0%-27.0%) and all-method coefficient of variation was 7.7% (range of method-specific coefficients of variation, 0.7%-25.8%). After controlling for reagent/instrument type, mean fibrinogen levels were 11.6% higher for prothrombin time-based reagents compared to Clauss (P < .001), and coefficient of variation was 46% lower for mechanical endpoint instruments compared to photo-optical. Most testing events (97.4%) could be reliably graded as pass or fail using a target range of ±20% from the method mean (total pass rate, 98.8%). Total fail rate was 3.0-fold lower for mechanical instruments compared to photo-optical (0.5% versus 1.5%, P = .001). Nonetheless many photo-optical methods had very high precision and very low fail rates. Fibrinogen assays showed highly variable methodology and performance characteristics. Bias, precision, and grading were affected by the type of reagent or instrument used.

External Quality Assurance of Antithrombin, Protein C, and Protein S Assays: Results of the College of American Pathologists Proficiency Testing Program in Thrombophilia

External Quality Assurance of Antithrombin, Protein C, and Protein S Assays: Results of the College of American Pathologists Proficiency Testing Program in Thrombophilia

External Quality Assurance of Antithrombin, Protein C, and Protein S Assays: Results of the College of American Pathologists Proficiency Testing Program in Thrombophilia

Hereditary and acquired deficiencies of antithrombin (AT), protein C (PC), and protein S (PS) are risk factors for venous thromboembolism. Proper diagnosis requires high-quality assays for these proteins. To determine the accuracy and interlaboratory precision of AT, PC, and PS assays used by laboratories participating in the United States College of American Pathologists proficiency testing program in thrombophilia and to grade the performance of laboratories. Standardized normal plasma with assigned analyte values was sent in 2 separate challenges to participating laboratories. Participants measured AT, PC, and PS levels using local methods. When compared with the assigned values for the international standard, the order of assay accuracy from highest to lowest was AT activity, PC antigen, AT antigen, total PS antigen, PC activity, PS activity, and free PS antigen (range of assay bias, 2.6%-8.8%). The order of assay precision from highest to lowest was PC activity, AT activity, AT antigen, total PS antigen, PS activity, free PS antigen, and PC antigen (range of assay coefficient of variation, 6.1%-20.0%). Most testing events (87.8%) could be graded as pass or fail using a target range of ±3 standard deviations from the method-specific mean. The pass rate was 98.2% for all AT, PC, and PS testing events combined. Accuracy and precision were higher for AT assays and lower for PC and PS assays. It was feasible to grade individual laboratory performance.

External quality assurance of antithrombin, protein C, and protein s assays: results of the College of American Pathologists proficiency testing program in thrombophilia.

Abstract Context.—Hereditary and acquired deficiencies of antithrombin (AT), protein C (PC), and protein S (PS) are risk factors for venous thromboembolism. Proper diagnosis requires high-quality a...

Automatic Failure in Gynecologic Cytology Proficiency Testing: Results From the College of American Pathologists Proficiency Testing Program

Automatic Failure in Gynecologic Cytology Proficiency Testing: Results From the College of American Pathologists Proficiency Testing Program

Automatic failure in gynecologic cytology proficiency testing: results from the College of American Pathologists proficiency testing program.

• Context.—Automatic failure in gynecologic cytology proficiency testing occurs when a high-grade lesion or carcinoma (HSIL+, Category D) is misinterpreted as negative for intraepithelial lesion or malignancy (Category B). Objectives.—To document the automatic failure rate in 2006 and 2007 from the College of American Pathologists proficiency testing program (PAP PT) and compare them to projected values from 2004. Design.—Identify automatic failures from PAP PT in 2006 and 2007 and compare the rates of failure regarding participant and preparation type to validated slides in the College of American Pathologists Interlaboratory Comparison Program in 2004. Results.—There were 65 264 participant responses for HSIL+ slides included in this analysis from 2006 and 2007. Overall, 1 % (666 of 65 264) of the HSIL+ responses were classified as negative, resulting in automatic failure for the participant. There were significantly fewer automatic failures in 2007 as compared with either 2006 or projected from 2004 data (P < .001). Conventional preparations had a lower automatic failure rate than liquid-based preparations but only for 2006. Both pathologists and cytotechnologists interpreting liquid-based preparations faired better than projected from 2004 data. Conclusions.—The automatic failure rate in PAP PT is lower than expected based on 2004 data from the College of American Pathologists Interlaboratory Comparison Program. Automatic failures are a relatively small component (1 % or less) of proficiency testing failures. The rate of automatic failure decreased from 2006 to 2007 and may be due to loss of poor performers in the testing pool, the test-taking environment, or removal of less robust slides from the program.

Automatic Failure in Gynecologic Cytology Proficiency Testing

AbstractContext.—Automatic failure in gynecologic cytology proficiency testing occurs when a high-grade lesion or carcinoma (HSIL+, Category D) is misinterpreted as negative for intraepithelial lesion or malignancy (Category B).Objectives.—To document the automatic failure rate in 2006 and 2007 from the College of American Pathologists proficiency testing program (PAP PT) and compare them to projected values from 2004.Design.—Identify automatic failures from PAP PT in 2006 and 2007 and compare the rates of failure regarding participant and preparation type to validated slides in the College of American Pathologists Interlaboratory Comparison Program in 2004.Results.—There were 65 264 participant responses for HSIL+ slides included in this analysis from 2006 and 2007. Overall, 1% (666 of 65 264) of the HSIL+ responses were classified as negative, resulting in automatic failure for the participant. There were significantly fewer automatic failures in 2007 as compared with either 2006 or projected from 2004 data (P &amp;lt; .001). Conventional preparations had a lower automatic failure rate than liquid-based preparations but only for 2006. Both pathologists and cytotechnologists interpreting liquid-based preparations faired better than projected from 2004 data.Conclusions.—The automatic failure rate in PAP PT is lower than expected based on 2004 data from the College of American Pathologists Interlaboratory Comparison Program. Automatic failures are a relatively small component (1% or less) of proficiency testing failures. The rate of automatic failure decreased from 2006 to 2007 and may be due to loss of poor performers in the testing pool, the test-taking environment, or removal of less robust slides from the program.

Performance of herpes simplex challenges in proficiency testing: observations from the College of American Pathologists proficiency testing program.

Abstract Context.—Herpes simplex virus (HSV) is a common sexually transmitted disease that is decreasing in prevalence. Herpes simplex virus challenge cases have performed well in the educational College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology. However, since gynecologic cytology proficiency testing (PT) was instituted, performance of HSV challenge cases has worsened. Objective.—To determine if the decrease in performance for HSV challenges is due to inexperience in identifying herpes virus or “gaming” of PT. Design.—We compare graded (field-validated) and ungraded (educational) slides with HSV prior to PT (1991– 2005) and after PT (2006 and 2007) in an attempt to characterize changes in performance of slides demonstrating purely HSV cellular features. All HSV slides were negative for intraepithelial lesion with the specific reference interpretation of HSV. Slides were excluded from analysis if they demonstrated more than one diagnostic category or had squamo...

Performance of Candida--fungal-induced atypia and proficiency testing: observations from the College of American Pathologists proficiency testing program.

Abstract Context.—Candida may elicit cellular changes on otherwise negative screening Papanicolaou tests that may be misinterpreted as atypical squamous cells of undetermined significance. Although these changes have been correctly interpreted in the educational program of the College of American Pathologists, the Interlaboratory Comparison Program in Gynecologic Cytology, the performance of negative slides with Candida faltered when the same field validated slides were included in proficiency testing (PT). Objective.—To identify the performance differences of negative for intraepithelial lesion (NILM) Candida challenges before and after PT. Design.—We compare the performance of NILM College of American Pathologists slides with Candida as a single reference diagnosis, prior to PT (1991–2006) and after PT (2006–2007). Results.—There were 147 186 responses for slides with NILM Candida from the College of American Pathologists programs from 1991 through 2007. After PT, 79.7% of incorrect participant response...

Performance of Herpes Simplex Challenges in Proficiency Testing: Observations From the College of American Pathologists Proficiency Testing Program

Herpes simplex virus (HSV) is a common sexually transmitted disease that is decreasing in prevalence. Herpes simplex virus challenge cases have performed well in the educational College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology. However, since gynecologic cytology proficiency testing (PT) was instituted, performance of HSV challenge cases has worsened. To determine if the decrease in performance for HSV challenges is due to inexperience in identifying herpes virus or "gaming" of PT. We compare graded (field-validated) and ungraded (educational) slides with HSV prior to PT (1991- 2005) and after PT (2006 and 2007) in an attempt to characterize changes in performance of slides demonstrating purely HSV cellular features. All HSV slides were negative for intraepithelial lesion with the specific reference interpretation of HSV. Slides were excluded from analysis if they demonstrated more than one diagnostic category or had squamous intraepithelial lesion in addition to HSV changes. A total of 40 634 HSV responses were evaluated. A significant difference existed in the diagnosis of HSV in PT compared with graded challenges prior to PT (96.6 versus 98.6; P < .001). No difference was seen in educational challenges pre-PT and post-PT (P = .14). No difference was present between slide preparation type; however, a difference was seen between cytotechnologist and pathologist response. There is a change in the performance of slide challenges demonstrating the cellular features of HSV in PT, most likely due to testing strategies of participants, rather than lack of recognition of HSV secondary to decreased prevalence.

Performance of Candida—Fungal-Induced Atypia and Proficiency Testing: Observations From the College of American Pathologists Proficiency Testing Program

Candida may elicit cellular changes on otherwise negative screening Papanicolaou tests that may be misinterpreted as atypical squamous cells of undetermined significance. Although these changes have been correctly interpreted in the educational program of the College of American Pathologists, the Interlaboratory Comparison Program in Gynecologic Cytology, the performance of negative slides with Candida faltered when the same field validated slides were included in proficiency testing (PT). To identify the performance differences of negative for intraepithelial lesion (NILM) Candida challenges before and after PT. We compare the performance of NILM College of American Pathologists slides with Candida as a single reference diagnosis, prior to PT (1991-2006) and after PT (2006-2007). There were 147,186 responses for slides with NILM Candida from the College of American Pathologists programs from 1991 through 2007. After PT, 79.7% of incorrect participant responses identified Candida as Category C (low-grade squamous intraepithelial lesion), whereas prior to PT only 59.5% of the incorrect diagnoses were low-grade squamous intraepithelial lesion (P < .001) in the field-validated component of the program. Validated Candida slides performed significantly more poorly in PT (97.2%) than prior to PT (98.3%) (P < .001). Candida challenges performed better in the educational component post-PT (98.3% versus 97.2%; P < .001). Cytotechnologists (97.9%) identified Candida more frequently than pathologists (97.3%) (P < .001) and ThinPrep preparations performed the best of all preparation types. Proficiency testing adversely affects the performance of participants in the identification of NILM Candida. Slides with Candida are more likely to be identified as low-grade squamous intraepithelial lesion in a PT exercise. Misidentification is not due to lack of recognition but most likely an attempt of test takers to optimize their likelihood of passing the examination.