Laboratory performance in HTLV-I/II analysis.

BACKGROUND: Since 1989, the CDC's Model Performance Evaluation Program has shipped samples to voluntary participant laboratories that test for HTLV antibodies. Each laboratory tests the well-characterized samples, reports the results, and provides information about its testing practices. The data from 15 performance survey periods are reported here. STUDY DESIGN AND METHODS: Multiple logistic regression was used to analyze all data from 15 survey periods from 1989 through 1996. RESULTS: The mean analytic sensitivity for EIA was 99.2 percent per survey period (range, 96-100%), the mean analytic specificity was 97.8 percent (75.6-100%), and the overall accuracy was 88.8 percent (63.8-100%). The mean analytic sensitivity for Western blot was 88.8 percent (75.6-100%); the mean analytic specificity was 95.7 percent (86.7-100%), and the overall accuracy was 91.1 percent (78.1-100%). CONCLUSIONS: Statistical analyses suggested associations between performance and both the retroviral serologic status of the sample and the analytical testing method. Western blot accuracy was associated with weekly testing volume. In early survey periods, performance problems were noted in the analysis of samples from donors with concomitant HTLV and HIV infections and those from donors who were positive for HTLV-II. Technological developments in test methods, such as the addition of recombinant antigens, appeared to have improved the laboratory performance of specific testing methods.

Do proficiency test results correlate with the work performance of screeners who screen Papanicolaou smears?

We rescreened Papanicolaou smear slides from 40,245 women, which had been examined by 81 cytology screeners, scored the screeners' work performance, and compared these scores with the results of the screeners' performance on glass slide and computer-based proficiency tests. All diagnoses (i.e., from the proficiency tests, the original slides, and the rescreened slides) were classified in the 4 diagnostic categories specified in the Clinical Laboratory Improvement Amendments. The rescreening scores were standardized to account for different distributions of abnormalities in the proficiency tests and rescreened slides. We compared a standardized score with the proficiency test scores. Of the cases, 91% were categorized as normal, benign, or reactive changes when rescreened, and 98% of these agreed with the original diagnosis. Sixteen percent of low-grade and 15% of high-grade intraepithelial lesions were classified as normal. The rank correlation between the rescreening scores and both proficiency tests was 0.24 using a scoring scheme for cytotechnologists. The correlation between the rescreening and proficiency testing scores indicates that performance on a 10-slide test gives some indication of the true performance of screeners. The computer-based test shows promise as an alternative to the glass slide test but needs further development and validation.

Variation in proficiency testing performance by testing site.

CONTEXT: Congress enacted the Clinical Laboratory Improvement Amendments of 1988 (CLIA) to promote uniform quality and standards among all testing sites in the United States. The performance indicators specified in the legislation are proficiency testing (PT) performance and periodic inspections. OBJECTIVE: To evaluate variation in PT performance by type of testing facility during the first year of compulsory participation under CLIA. DESIGN: All 1994 PT score data electronically reported to the Health Care Financing Administration as a component of compliance with the CLIA regulations were obtained. Over 1.2 million PT event scores from 17058 unique testing sites were sorted into 2 groups based on the type of testing facility: hospitals and independent laboratories (HI) and all other testing sites (AOT). MAIN OUTCOME MEASURES: Satisfactory and unsatisfactory performance rates for HI and AOT for each analyte and/or test, according to the criteria specified by the CLIA regulations. RESULTS: The aggregate rates of satisfactory event performance for all regulated analytes, tests, and specialties were 97% and 91% for the HI and AOTgroups, respectively. The aggregate odds ratio for unsatisfactory PT event performance for the AOT group compared with the HI group was 2.89, with a range of 2.19 to 7.51 for the individual analytes. CONCLUSION: There was a consistent difference in PT performance during the first full year of compulsory PT under the CLIA regulations based on the type of testing facility performing the analysis. Traditional testing sites achieved higher rates of satisfactory performance than newly regulated, alternative testing sites.

Quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. Identification of variables associated with laboratory performance.

To identify factors that may affect the quality of laboratory performance of human immunodeficiency virus type 1 (HIV-1) antibody testing, the Centers for Disease Control and Prevention Model Performance Evaluation Program surveyed laboratories in 1989 that performed enzyme immunoassay (EIA) and Western blot tests for HIV-1 antibody. Panels of 10 HIV-1-antibody-positive and antibody-negative plasma samples, some of which were duplicates, were mailed to program-participating laboratories. Laboratories were also mailed survey questionnaires to ascertain their laboratory characteristics and testing practices. Using 1988 data, researchers previously found that the overall analytic performance of laboratories performing HIV-1 antibody testing was independently associated with the following: (1) requiring a minimum degree of testing personnel; (2) having written criteria for identifying unsatisfactory specimens; (3) requiring in-house training for testing personnel; (4) having tested more than 10,000 specimens; (5) being identified as an "other" laboratory type; (6) having more than 24 months of testing experience; (7) laboratory uses specific (Abbott) materials for EIA; and (8) testing specimens collected by family-planning clinics. To verify these findings, we performed multivariate analysis on 1989 performance data. For the 1989 EIA analytic sensitivity, significant positive (P < or = .05) associations were detected with having written criteria for identifying unsatisfactory specimens and with having tested more than 10,000 specimens. For the 1989 overall EIA analytic performance, a significant negative (P < or = .05) association was found with using specific (Abbott) EIA materials, and a significant positive (P < or = .05) association was found with having tested more than 10,000 specimens. For Western blot results, the only significant (P < or = .05) associations were for both analytic sensitivity and overall analytic performance and having tested more than 10,000 specimens.

Analytic sensitivity and specificity of enzyme immunoassay results in testing for human immunodeficiency virus type 1 antibody.

In 1986, a performance evaluation program at the Centers for Disease Control was implemented to assess the quality of performance of laboratories testing for human immunodeficiency virus type 1 antibody and to identify problems that occur during the testing process. Laboratories participating in the Centers for Disease Control Model Performance Evaluation Program for human immunodeficiency virus type 1 antibody testing furnished enzyme immunoassay results after they tested performance evaluation panels that were sent to them in August and November 1989. The panels consisted of 10 individual samples containing antibody-negative and antibody-positive samples, some of which were duplicates. Not all laboratories received the same panel of samples. Low false-negative and false-positive rates, as well as high intrashipment and intershipment reproducibility, indicate that most laboratories did not experience difficulty in testing performance evaluation samples sent to them in August and November 1989.

Quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. Variables associated in multivariate analyses.

In May 1988, the Centers for Disease Control's Model Performance Evaluation Program (Atlanta, Ga) surveyed 1092 laboratories that performed enzyme immunoassays and Western blot tests for human immunodeficiency virus type 1 antibody on mailed plasma samples of known human immunodeficiency virus type 1 antibody reactivity and that described their laboratory characteristics and testing practices. The study objective was to evaluate the quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. After identifying relevant variables in univariate analyses, multivariate analyses were performed using stepwise logistic models. Human immunodeficiency virus type 1 antibody test performance was independently associated with analytic variables such as commercial test kit used and with nonanalytic variables such as experience, training, and degree requirements of laboratory personnel. These results validate the importance of nonanalytic variables to the quality of outcomes in laboratory testing.

HLA-B8 in sarcoidosis.

One hundred and seventy-four unrelated white patients with biopsied and clinically diagnosed sarcoidosis and a reference population of 97 were tested for HLA antigens. Selected comparisons showed a statistically significant association of HLA-B8 with the sarcoidosis group (28.9%) when compared to the reference group (15.5%).