The microINR portable coagulometer: analytical quality and user-friendliness of a PT (INR) point-of-care instrument

Abstract

Regular measurement of prothrombin time as an international normalized ratio PT (INR) is mandatory for optimal and safe use of warfarin. Scandinavian evaluation of laboratory equipment for primary health care (SKUP) evaluated the microINR portable coagulometer (microINR^®) (iLine Microsystems S.L., Spain) for measurement of PT (INR). Analytical quality and user-friendliness were evaluated under optimal conditions at an accredited hospital laboratory and at two primary health care centres (PHCCs). Patients were recruited at the outpatient clinic of the Laboratory of Medical Biochemistry, St Olav’s University Hospital, Trondheim, Norway (n = 98) and from two PHCCs (n = 88). Venous blood samples were analyzed under optimal conditions on the STA-R^®Evolution with STA-SPA + reagent (Stago, France) (Owren method), and the results were compared to capillary measurements on the microINR^®. The imprecision of the microINR^® was 6% (90% CI: 5.3–7.0%) and 6.3% (90% CI: 5.1–8.3) in the outpatient clinic and PHCC2, respectively for INR ≥2.5. The microINR^® did not meet the SKUP quality requirement for imprecision ≤5.0%. For INR <2.5 at PHCC2 and at both levels in PHCC1, CV% was ≤5.0. The accuracy fulfilled the SKUP quality goal in both outpatient clinic and PHCCs. User-friendliness of the operation manual was rated as intermediate, defined by SKUP as neutral ratings assessed as neither good nor bad. Operation facilities was rated unsatisfactory, and time factors satisfactory. In conclusion, quality requirements for imprecision were not met. The SKUP criteria for accuracy was fulfilled both at the hospital and at the PHCCs. The user-friendliness was rated intermediate.

Keywords:

• International normalized ratio
• point-of-care systems
• point-of-care testing
• quality control
• warfarin

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Acknowledgements

This manuscript was written by the participants of the ‘Course in Manuscript Writing and Publishing’ arranged by the Editorial Board of The Scandinavian Journal of Clinical and Laboratory Investigation at Finse, Norway, January 2016. The authors paid respect to the formal agreement between SKUP and iLine Microsystems. We are grateful for the permission to use the data from the SKUP report. We would especially like to thank Grete Monsen from SKUP for answering any questions regarding the report. We also thank Anne Christin Breivik from SKUP for through reading of the manuscript. Thanks to Elvar Theodorsson, Tor-Arne Hagve, Sverre Sandberg, Olav Klingenberg, Anders Kallner, Axel Brock and Jens Peter Berg for supervision during writing and revision of the manuscript. The Figures used in the current report are from the original SKUP report.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. There was no external funding.

Additional information

Funding

The authors declare that they participated on a course sponsored by SJCLI and the Nordic Society for Clinical Chemistry (NFKK).