NCT07418099

External Multicenter Validation of the APTTO Model for Prolonged APTT Using Clot Waveform Analysis

Multicenter External Validation of the APTTO Predictive Model Based on Clot Waveform Analysis for the Assessment of Prolonged Activated Partial Thromboplastin Time

• Status: Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 1,500 (estimated)
• Sponsor: Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz · Academic / Other
• Sex: All
• Age: —
• Healthy volunteers: Not accepted

Summary

Prolonged activated partial thromboplastin time (APTT) is a frequent laboratory finding that may reflect a broad spectrum of underlying conditions, ranging from benign laboratory abnormalities to clinically relevant hemostatic disorders. Clot waveform analysis (CWA), automatically generated during routine APTT testing by optical coagulation analyzers, provides additional quantitative and qualitative information on clot formation dynamics. The APTTO model is a previously developed two-step predictive algorithm based on CWA features designed to estimate the probability of a pathological cause of prolonged APTT and to differentiate lupus anticoagulant from intrinsic pathway factor deficiency or von Willebrand disease. Internal validation has demonstrated good discrimination and calibration. This multicenter observational study aims to perform an external validation of the APTTO model in independent patient cohorts, assessing its discrimination, calibration, and decision-analytic performance without model updating.

Detailed description

This multicenter observational cohort study is designed to externally validate the APTTO predictive model in patients with prolonged APTT and normal prothrombin time evaluated in routine clinical practice across multiple hospitals. All laboratory data, including CWA parameters and waveform morphology, are generated as part of standard diagnostic workflows. No additional blood sampling, laboratory testing, or modifications to clinical management are introduced for research purposes. The study focuses on evaluating model performance in independent cohorts by applying the original APTTO model coefficients and predefined cut-offs without recalibration or re-estimation. Model discrimination, calibration, and decision-analytic measures will be assessed. Secondary analyses will explore model performance across predefined subgroups and analytical robustness. This study adheres to the TRIPOD statement for validation of prediction models.

Conditions

• Coagulation Disorder, Blood
• Prolonged APTT

Interventions

Type	Name	Description
OTHER	Clot waveform analysis-based risk stratification (APTTO models)	Application of the APTTO predictive models (APTTO1 and APTTO2) to clot waveform analysis parameters generated during routine activated partial thromboplastin time testing, for research purposes only. The model output does not influence clinical management or surgical decision-making during the study.

Timeline

• Start date: 2026-01-13
• Primary completion: 2027-03-01
• Completion: 2027-03-01
• First posted: 2026-02-18
• Last updated: 2026-04-06

Locations

16 sites across 1 country: Spain