No abstract

Indirect immunofluorescence (IIF) is considered by the American College of Rheumatology (ACR) and the international consensus on ANA patterns (ICAP) the gold standard for the screening of anti-nuclear antibodies (ANA). As conventional IIF is labor intensive, time-consuming, subjective, and poorly standardized, there have been ongoing efforts to improve the standardization of reagents and to develop automated platforms for assay incubation, microscopy, and evaluation. In this study, the workflow and performance characteristics of a fully automated ANA IIF system (Sprinter XL, EUROPattern Suite, IFA 40: HEp-20-10 cells) were compared to a manual approach using visual microscopy with a filter device for single-well titration and to technologist reading. The Sprinter/EUROPattern system enabled the processing of large daily workload cohorts in less than 8 h and the reduction of labor hands-on time by more than 4 h. Regarding the discrimination of positive from negative samples, the overall agreement of the EUROPattern software with technologist reading was higher (95.6%) than when compared to the current method (89.4%). Moreover, the software was consistent with technologist reading in 80.6–97.5% of patterns and 71.0–93.8% of titers. In conclusion, the Sprinter/EUROPattern system provides substantial labor savings and good concordance with technologist ANA IIF microscopy, thus increasing standardization, laboratory efficiency, and removing subjectivity.

No abstract

The presented statistical algorithm is shown to be an accurate and practical tool for reference interval calculations.

A reference interval (RI) 10 is a standard component of reporting a laboratory result and is important to transform a numerical value into clinically meaningful information. An RI is intended to inform the clinical care provider that laboratory values within the interval indicate a nondiseased condition. The most common approach is to base an RI on the central 95% of laboratory test values observed for a reference population that is free of diseases that influence that laboratory test result. Because many diseases are asymptomatic, it becomes difficult to qualify people for a nondiseased condition, thus biasing the selection of reference individuals. Furthermore, information on the full complement of disease conditions that influence a laboratory test may be unknown. Thus, RIs may be influenced by inappropriately selected reference populations.Another limitation in determining an RI is obtaining an adequate sample of a reference population to make an estimate of the central 95% of results with suitable uncertainty to be meaningful for interpreting a test result. The sample size requirement becomes even larger when partitioning by sex, age, ethnicity, menstrual cycle, and other parameters is necessary for meaningful RIs. CLSI Guideline EP28-A3c describes consensus approaches and some limitations for establishing and verifying RIs. However, some of the approaches in this guideline are statistically underpowered such that uncertainties in the RIs may not be appreciated.A particularly challenging situation is the requirement for laboratories to establish an RI for a laboratory developed measurement procedure (MP) or to verify the RIs proposed by the manufacturer of an in vitro diagnostic (IVD) MP. Identifying a suitable reference population for either requirement can be very challenging.Evolution in laboratory practice is needed to enable appropriate RIs to be adopted by laboratories. We asked experts with different perspectives to address issues we all face in establishing or verifying RIs. How can an IVD device manufacturer get a suitable sample of a reference population to establish an RI?Ferruccio Ceriotti: "The RIs for the quantities being determined" are required from an IVD manufacturer to comply with the European Directive on in vitro diagnostic medical devices. Moreover, the RIs provided by the manufacturer are probably those most commonly used on clinical laboratory reports. There is not a single answer to this critical question, it depends on the measurand. If a reference system exists for calibration traceability and there are published well-characterized RIs obtained with a well-standardized MP ("traceable RIs"), the manufacturer can provide those RIs without the need of a new RI study provided that its MP has the same level of standardization. For nonstandardized measurands, I do not see alternatives to an RI study performed according to CLSI