CRYOcheck Chromogenic Factor VIII

CRYOcheck Chromogenic Factor VIII is an in vitro diagnostic test for clinical laboratory use that quantitatively measures factor VIII activity in citrated human plasma. It is used to identify factor VIII deficiency and aid in managing hemophilia A in patients aged 2 years and older.

The device uses a two-stage chromogenic assay principle. In stage one, test plasma is mixed with calcium, phospholipids, human thrombin, FIXa, and bovine FX to activate factor VIII. In stage two, factor Xa production is measured by cleavage of a chromogenic substrate, with results expressed as percent activity relative to a calibration curve. The key modification from the predicate is substitution of bovine FIXa for human FIXa in Reagent 2.

Interference studies were conducted according to CLSI EP07-A3 (Clinical and Laboratory Standards Institute guideline for evaluating interference).

The applicant demonstrated substantial equivalence by showing that all performance characteristics—including precision, reproducibility, accuracy, reference intervals, shelf-life stability, in-use stability, linearity, and detection capability—are substantially equivalent to the predicate device K193204. The primary change (bovine FIXa replacing human FIXa) and expanded interference/recovery claims were supported by comprehensive performance testing on the same instrument platforms, with results showing the modified device performs identically to the predicate for its intended use.