Electronic "Quality Control" (EQC): is it just for unit use devices?

The US Clinical Laboratory Improvement Amendments of 1988 (CLIA'88) mandated daily quality control (QC) for all laboratory tests. CLIA'88 clearly envisioned traditional, matrix-based controls. However, recent interpretations allow routine use of "electronic" controls (EQC). These surrogate controls, reference cassettes, glass filters, electronic signals, etc., evaluate the photometric, electronic and computational components of the test system. EQC does not evaluate chemical reactions, sample and reagent manipulations, etc. When compared to traditional concepts, it represents a discontinuity in logic and subverts the fundamental purpose of QC. The advent of "unit-use" test systems (reagent packs, cassettes, cartridges, etc.) used primarily in decentralized testing locations opened the door to EQC. The rationale behind EQC is that if the test system is operating within specifications and the manufacturer reliably delivers consistent and uniform quality products, a simple electronic check will assure that the entire testing process is in control. Unrecognized test system failure is the most insidious problem facing today's instruments using EQC-based systems. We cite positive and negative examples. We also ask, "If EQC is accepted, from a regulatory perspective for some instruments, why not for all?" Is the next step universal EQC, for all systems, inevitable?