Variability of anti-PF4/heparin antibody results obtained by the rapid testing system ID-H/PF4-PaGIA

Schneiter, S; Colucci, G; Sulzer, I; Barizzi, G; Lämmle, B; Alberio, L (2009). Variability of anti-PF4/heparin antibody results obtained by the rapid testing system ID-H/PF4-PaGIA. Journal of thrombosis and haemostasis, 7(10), pp. 1649-55. Oxford: Wiley-Blackwell 10.1111/j.1538-7836.2009.03507.x

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BACKGROUND: Recent studies have shown that a low clinical pretest probability may be adequate for excluding heparin-induced thrombocytopenia. However, for patients with intermediate or high pretest probability, laboratory testing is essential for confirming or refuting the diagnosis. Rapid assessment of anti-PF4/heparin-antibodies may assist clinical decision-making. OBJECTIVES: To evaluate the performance of rapid ID-H/PF4-PaGIA. In particular, we verified reproducibility of results between plasma and serum specimens, between fresh and frozen samples, and between different ID-H/PF4-polymer lots (polystyrene beads coated with heparin/PF4-complexes). PATIENTS/METHODS: The samples studied were 1376 plasma and 914 corresponding serum samples from patients investigated for suspected heparin-induced thrombocytopenia between January 2000 and October 2008. Anti-PF4/heparin-antibodies were assessed by ID-H/PF4-PaGIA, commercially available ELISAs and heparin-induced platelet aggregation test. RESULTS: Among 914 paired plasma/serum samples we noted discordant results (negative vs. low-titre positive) in nine instances (1%; 95%CI, 0.4-1.6%). Overall, agreement between titres assessed in plasma vs. serum was highly significant (Spearman correlation coefficient, 0.975; P < 0.0001). Forty-seven samples tested both fresh and after freezing/thawing showed a good agreement, with one discordant positive/negative result (Spearman correlation coefficient, 0.970; P < 0.0001). Among 1376 plasma samples we noted a strikingly variable incidence of false negative results (none - 82%; 95%CI, 66-98%), depending on the employed ID-H/PF4-polymer lot. Faulty lots can be recognized by titrating commercial positive controls and stored samples of HIT-patients. CONCLUSION: Laboratories performing the assay should implement stringent internal quality controls in order to recognize potentially faulty ID-H/PF4-polymer lots, thus avoiding false negative results.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Haematology and Central Haematological Laboratory
UniBE Contributor:	Colucci, Giuseppe, Lämmle, Bernhard, Alberio, Lorenzo
ISSN:	1538-7836
Publisher:	Wiley-Blackwell
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 15:10
Last Modified:	05 Dec 2022 14:21
Publisher DOI:	10.1111/j.1538-7836.2009.03507.x
PubMed ID:	19515091
Web of Science ID:	000270129200007
URI:	https://boris.unibe.ch/id/eprint/30900 (FactScience: 195258)