Guideline References

Measurement Procedure Comparison and Bias Estimation Using Patient Samples

The primary standard governing method comparison study design and analysis. EP09C specifies minimum sample requirements (≥40 patient samples, preferably 100+), regression techniques (Deming, Passing-Bablok, OLS), difference plots, and bias estimation at clinical decision points. The PT/INR Method Comparison module applies these techniques to both PT and INR data derived from the same paired samples.

One-Stage Prothrombin Time (PT) Test and Activated Partial Thromboplastin Time (APTT) Test

Governs PT/INR system performance verification, including reagent sensitivity and method equivalence. H47-A2 provides context for the clinical significance of PT and INR agreement criteria, particularly for patients on oral anticoagulation therapy where INR accuracy is safety-critical.

Standard: Establishment and Verification of Method Performance Specifications

CLIA requires verification of accuracy relative to a comparison method for all non-waived tests. For PT/INR, this includes demonstrating agreement between the new and reference method across the clinically relevant measurement range before reporting patient results.