Evaluation of children with a suspected bleeding disorder applying the Impact-R [Cone and Plate(let) Analyzer]

J Thromb Haemost. 2009 Dec;7(12):1990-6. doi: 10.1111/j.1538-7836.2009.03628.x. Epub 2009 Oct 3.


Background: A convenient screening test for children with bleeding symptoms before more labor-intensive diagnostic steps are taken would be of value. The Impact-R was designed in an attempt to analyse platelet function under near physiological conditions. Results are presented as surface coverage (SC, %) and average size (AS, microm(2)).

Objective: In this cross-sectional retrospective study, we assessed the use of the Impact-R in the evaluation of children with a suspected bleeding disorder (BD).

Methods: The hospital charts of 110 children referred to the coagulation laboratory were reviewed for personal and family bleeding history (BH) as well as results of the laboratory evaluation.

Results: A laboratory 'diagnosable' BD (LBD) was found in 23 children (21%, 95% CI 14-30%). A diagnosis of LBD was associated with the severity of bleeding but not with family BH. By receiver-operating characteristic (ROC) curve analysis, the SC was superior to the AS for diagnosis of a LBD. The Impact-R was abnormal in 43/97 children (44.3%, 95% CI 34-55%). The predictive values of a normal and abnormal Impact-R were 96% (95% CI 92-97%) and 42% (95% CI 28-56%), respectively. When considering the personal and family BH, the post-test probability for LBD after a normal Impact-R was reduced from 20% to 3.5% (95% CI 2.5-7%).

Conclusions: A normal Impact-R test is highly effective in excluding LBDs. Yet, in case of an abnormal Impact-R test, further testing is needed. An algorithm that includes the personal and family BH and the results of a screening test may improve the diagnostic process. Prospective studies are now needed to confirm these findings.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Blood Coagulation Disorders / diagnosis*
  • Blood Platelet Disorders
  • Child
  • Child, Preschool
  • Cohort Studies
  • Cross-Sectional Studies
  • Family Health
  • Female
  • Humans
  • Infant
  • Male
  • Mass Screening / methods
  • Platelet Function Tests / instrumentation*
  • ROC Curve
  • Retrospective Studies