Performance of a point‐of‐care device in determining prothrombin time in supra‐therapeutic INRs

Abstract

Our results demonstrate that POC devices present good correlation with standard laboratory methods for PT determination in supra-therapeutic INRs and that differences in clinical management do not support the need for systematic confirmation of these results in nonbleeding patients.

Performance evaluation of the microINR® point‐of‐care INR‐testing system

“…A possible practical solution to the poorer concordance observed in this group would be to confirm all POC INR values > 4.0 with a validated laboratory method on venous blood. However, Hashimoto et al argued previously that such a recommendation is not sufficiently evidence‐based. This would probably not impact work‐flow significantly, as it would lead to approximately only 1‐2 additional confirmatory venous blood INRs per day at our institution, but will increase costs.…”

“…ISO standard 17593:2007 recommends that all INR values > 6.0 be excluded from final data analysis . For the purposes of this study, however, only participants with INR values > 8.0 were excluded from data analysis, as a recent publication has asserted that patients with supra‐therapeutic INRs are not sufficiently represented in the studies that validated these devices . All subjects with incomplete data were excluded from the relevant analysis as per ISO standard 17593:2007…”

“…They provide the ability to measure the INR on a small volume of capillary blood obtained by simple finger‐prick, with a marked reduction in the turn‐around‐time as results are virtually instantaneously available. The use of a POC device is generally simple and can often be performed without the assistance of a medical professional, following suitable training.…”

“…Several studies have demonstrated the precision and accuracy of POC instruments . However, these instruments also have their limitations.…”

“…However, these instruments also have their limitations. The precision, accuracy and linearity of most instruments decrease with INR values above 5.0, although the clinical relevance of this observation has been questioned, and the preferential use of laboratory INRs deemed unnecessary, in the supra‐therapeutic range . The effects of interference from other medications, suboptimal pre‐analytical influences (such as haemolysis, icterus, lipaemia and the lupus anticoagulant), have also not been evaluated extensively .…”