Analytical performance specifications based on the state-of-the-art for the newborn screening

Introduction: For the measurands of the newborn screening (NBS), there are no analytical performance specifications (APS) available based on the Milan consensus Models. The objective is to provide total error (TE) APS based on the state-of-the-art (SOTA) for the NBS. Material and Methods: 23,662 results were collected from the Spanish NBS EQA scheme between May 2015 and September 2018. Measurands included: thyroid-stimulating hormone (TSH), immunoreactive trypsinogen (IRT), phenylalanine (Phe), tyrosine (Tyr), free carnitine (C0), acetylcarnitine (C2), propionylcarnitine (C3), butyrylcarnitine (C4), isovalerylcarnitine (C5), glutarylcarnitine (C5DC), hexanoylcarnitine (C6), octanoylcarnitine (C8), decanoylcarnitine (C10), myristoylcarnitine (C14), palmitoylcarnitine (C16), stearoylcarnitine (C18). TE APS were calculated as the 90th percentile of the measurement errors, considering 75% of the best results from each laboratory only. It was also studied whether the analytical performance was concentration-dependent. Results: When TE APS were calculated including all methods, TSH, IRT, C16 and C18 showed the best analytical performance and Phe, C5DC and C10 showed the worst. Generally, TE APS decreased when considering only majority methods and higher TE APS were obtained for lower concentrations. Discussion Due to the lack of APS based on superior models, the proposed TE APS based on the SOTA can help NBS laboratories to set quality specifications.