Comparative evaluation of newborn bloodspot specimen cards by experienced laboratory personnel and by an optical scanning instrument

Abstract

A major factor in determining the suitability of a dried blood spot (DBS) specimen is the subjective nature of evaluation by laboratory personnel. Using newborn screening DBS specimen cards as they were submitted to a public health NBS program, we conducted a systematic pilot study of DBS evaluation by multiple experienced laboratory personnel (ELP) and by an automated optical scanning instrument (OSI) (CardScan (tm), BSD Robotics). OSI confirmed the satisfactory status of all newborn DBS specimen cards that passed initial review by the first ELP. Among the questionable cards selected for further review, 58% passed multiple ELP consensus assessment, and 62% passed OSI evaluation. The overall agreement between ELP and OSI was 86%. Among questionable specimen cards, ELP and OSI were more strongly correlated when multiple ELP assessment was unanimous. We conclude that subjective assessment by ELP is essential and that OSI evaluation is a useful adjunct when ELP assessment does not reach consensus. OSI further allows the selection of optimal locations for punching DBS from unsatisfactory or questionable specimens, optimizing the quality of interim analyses that may be conducted while repeat specimens are being collected. Instrument evaluation of specimen cards would also be valuable as an independent reference method for training laboratory and specimen collection personnel. OSI technology merits further studies to confirm and extend our findings.

Keywords: Automation; Dried blood spots; Evaluation; Newborn bloodspot screening; Specimen quality; Training.

Figure 1.. Optical Scanning Instrument Dried Blood Spot Evaluation Algorithm

Flow chart for the Cardscan Dried Blood Spot Scan Instrument showing the parameters and pathways for evaluation.

Figure 2.. Newborn DBS Specimen collection cards and Optical Scanning Instrument (OSI) Scanned Images

A. OSI instrument found 20 acceptable punch areas in 3 DBS, the minimum required for an acceptable evaluation by laboratory-designated criteria. B. The OSI instrument found only 17 acceptable punch areas in 2 DBS, resulted in an unacceptable evaluation. The remaining 3 DBS did not have any acceptable punch locations.

Figure 3.. Overall Agreement between Evaluation by an Optical Scanning Instrument (OSI) and Assessment by Experienced Laboratory Personnel (ELP)

The first bar shows 100% agreement between OSI and ELP for 100 DBS cards rated as “satisfactory” in the initial ELP assessment. The second bar represents 76% agreement for 45 cards initially rated as questionable and subsequently assessed as satisfactory by at least two of the three ELP. The third bar represents 57% agreement among the 32 cards initially assessed as questionable and subsequently assessedas unsatisfactory by at least two of the three ELP. OSI questionable results were considered the equivalent of unsatisfactory.

Figure 4.. Categorical Agreement between Evaluation by an Optical Scanning Instrument (OSI) and by Experienced Laboratory Personnel (ELP)

Date from Figure 2 are depicted in their individual categories, including the questionable OSI evaluation category.