The Activated Partial Thromboplastin Time (APTT) is used for a variety of reasons, including (i) as a screening test to assess potential deficiencies within patient plasmas of certain coagulation clotting factors, and (ii) to monitor the anticoagulant status of patients, principally those receiving regular heparin therapy. Previous studies, typically evaluating small numbers of individual APTT reagents, have shown that such reagents can differ substantially in respect to their sensitivity to factor deficiencies and other properties. The pattern of behaviour to the above can heavily influence the laboratory choice regarding which reagent best suits their needs. In view of this, and ever changing APTT reagent formulation, reagent availability, and due to limitations of previous studies, we have evaluated the behaviour of 18 APTT reagents (17 commercially available) to a variety of parameters, including those noted above, and utilising two automated coagulation analysers (the Coag-a-mate X2 and the ACL-300R). Whilst most reagents followed similar and acceptable patterns of behaviour, there were notable exceptions. Thus, of the 18 reagents tested, and using either instrument, and commercially available FVIII deficient plasmas to generate factor sensitivity curves, 5 reagents showed discrepant sensitivity to deficiency of Factor VIII. In addition, only 3 reagents showed relative insensitivity to Factor XII, a desirable reagent trait. Sensitivity to Factors IX and XI was similar for most reagents. In general, there was little detectable difference in the behaviour of the two instruments with respect to factor level sensitivity. Whilst there was some variation in respect to normal APTT 'reference' ranges derived for the reagents tested, there was little detectable difference between instruments. All reagents tested showed upward linearity in respect to heparin sensitivity, although there was some difference in the degree of sensitivity detected. Again, there was little difference between instruments for most reagents tested. It is hoped that the current study will provide a broad overview of the behaviour of currently available commercial APTT reagents, and should be of help to coagulation laboratories attempting to decide which reagent best suits their particular technical and clinical needs.
|Number of pages||8|
|Journal||Australian Journal of Medical Science|
|Publication status||Published - 1994|