What question did this study set out to answer?

To determine if calibrating routine thromboplastins against international reference standards and expressing prothrombin time results as the International Normalized Ratio (INR) improves inter-laboratory comparability.

January 1, 1987Thrombosis and Haemostasis

Oral Anticoagulant Therapy Control: Evidence that INR Expression Improves the Inter-Laboratory Comparability of Results - The Bologna Oral Anticoagulant Control Exercise

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Why the study?

Does expressing prothrombin time results as INR reduce interlaboratory variability compared to percentage activity in patients on oral anticoagulants?

Population

64 subjects tested across 9 laboratories in the Bologna area.

Comparison

Expression of prothrombin time results as… vs Expression of prothrombin time results as…

Design

Other

Follow-up

8 days

Authors

GPGualtiero PalaretiVascular Medicine SCS CoccheriGeneral / Preventive / Lipids MPM PoggiUniversity of Bologna

Discussion

Member takes

Implication

Supports INR standardization for reliable oral anticoagulant monitoring; leaves open prospective outcome validation across settings.

Key Points

To determine if calibrating routine thromboplastins against international reference standards and expressing prothrombin time results as the International Normalized Ratio (INR) improves inter-laboratory comparability.
Conducted prothrombin time testing across 9 laboratories over 8 days using customary coagulometers and 5 different thromboplastin brands.
Assayed blood samples from 16 healthy control subjects and 48 patients receiving oral anticoagulant therapy.
Evaluated International Sensitivity Index (ISI) stability and compared direct calibration against international reference materials versus intermediate local standards.
Interlaboratory coefficient of variation (CV) for prothrombin ratios was 15% across all thromboplastins, but dropped to 5.8%–8.9% when brand and batch were standardized.
ISI values derived via direct international calibration closely matched intermediate local standard calibration and showed minimal variation across different coagulometer models.
Reporting results as INR values instead of percentage activity substantially lowered interlaboratory variation and increased measurement uniformity.

Structured PICO

Does expressing prothrombin time results as INR reduce interlaboratory variability compared to percentage activity in patients on oral anticoagulants?

Population

64 subjects (16 normal subjects and 48 patients on oral anticoagulants) tested across 9 laboratories in the Bologna area.

Intervention

Expression of prothrombin time (PT) results as International Normalized Ratio (INR)

Comparator

Expression of prothrombin time (PT) results as percentage activity

Outcome

Interlaboratory variability and uniformity of anticoagulation level measurementssurrogate

Expressing prothrombin time results as INR rather than percentage activity significantly reduces interlaboratory variability, improving the reliability of oral anticoagulant monitoring.

Cite This Study

Palareti et al. (1987) studied this question.

synapsesocial.com/papers/6a859ff4c670f88be7ae7291 https://doi.org/10.1055/s-0038-1646013

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Oral Anticoagulant Therapy Control: Evidence that INR Expression Improves the Inter-Laboratory Comparability of Results - The Bologna Oral Anticoagulant Control Exercise

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Oral Anticoagulant Therapy Control: Evidence that INR Expression Improves the Inter-Laboratory Comparability of Results - The Bologna Oral Anticoagulant Control Exercise

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider