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.