Key Points
- To develop a simplified nomogram for deriving International Normalised Ratios (INR) from prothrombin times without requiring logarithmic calculations or scientific calculators.
- Calculated relationships between prothrombin time ratios and reagent responsiveness using the established World Health Organization calibration formula.
- Constructed a graphical nomogram accommodating the full spectrum of thromboplastin International Sensitivity Index (ISI) values between 1.0 and 3.0.
- Provided a direct graphical interpretation of INR values across the known ISI range of 1.0 to 3.0.
- Eliminated the requirement for exponential mathematical operations or logarithmic scientific calculators in routine coagulation reporting.
Structured PICO
IInterventionA nomogram for the derivation of International Normalised Ratios (INR) for thromboplastins between 1.0 and 3.0 ISI
CComparatorScientific calculator or alternative formula and logarithms
OOutcomeDerivation of INR without the need for calculations
The presented nomogram simplifies the derivation of INR from prothrombin times, facilitating the general application of the INR system without complex calculations.