Patient self‐testing is a reliable and acceptable alternative to laboratory INR monitoring

Abstract

SummaryAn ageing population and the continuing expansion of clinical indications for coumadin therapy have increased pressure on hospital anticoagulant clinics. One solution is patient self-testing (PST) of the international normalized ratio (INR) using capillary blood samples on point-of-care coagulation monitors at home. We conducted a prospective study to determine whether patients can achieve accurate INR values through PST, using the CoaguChek S (Roche Diagnostics, Lewes, UK). The main outcome measurements were: comparability of INR values obtained by PST and the hospital laboratory, patient acceptability as assessed by a questionnaire and anticoagulant control. Eighty-four patients [53 men, 31 women; median age 59 years (range 26-83)], receiving long-term oral anticoagulation (warfarin), were recruited from our Anticoagulation Clinic. Patients were randomized to weekly self-testing or continuing 4-weekly hospital laboratory monitoring of INR. Comparison of INRs (n ¼ 234) showed no significant differences between the CoaguChek (median INR 3AE02) and laboratory testing (median INR 3AE07). There was excellent correlation between the two methods (r ¼ 0AE95), with 85% of CoaguChek results within 0AE5 INR units of the laboratory method. On four occasions, differences of >1 unit INR were obtained, but in each case the patient's anticoagulation was unstable (INR >4AE5 by both methods) and the differences in INR would not have altered patient management. 87% of patients found self-testing straightforward, 87% were confident in the result they obtained and 77% preferred self-testing. We conclude that PST is a reliable alternative to hospital clinic attendance and is acceptable to the majority of suitably trained patients.

The clinical effectiveness and cost-effectiveness of point-of-care tests (CoaguChek system, INRatio2 PT/INR monitor and ProTime Microcoagulation system) for the self-monitoring of the coagulation status of people receiving long-term vitamin K antagonist therapy, compared with standard UK practice: systematic review and economic evaluation

“…The majority of included trials were conducted in Europe: six trials were conducted in Germany, 57,59,60,70,72,78 six in the UK, 45,56,64,67,69,73 three in Denmark, 58,66,75 three in the Netherlands, 68,76,79 one in Ireland, 62 one in Austria, 63 one in France 77 and one in Spain. 61 Three trials were conducted in Canada 55, 65,74 and one in the USA.…”

“…The safety and reliability of CoaguChek S and CoaguChek XS have been demonstrated in several studies in both adults and children. [43][44][45][46][47][48][49][50] A number of studies have also compared the performance of CoaguChek S with that of CoaguChek XS in relation to conventional INR measurement. Even though a good agreement between the two CoaguChek models and conventional laboratory-based results has been demonstrated, CoaguChek XS has shown more accurate and precise results than its precursor in both adults and children, especially for higher INR values (> 3.5).…”

“…58,60,62,78 Eight of the 26 included trials were at high risk of attrition bias, with more than 5% dropout rate and with missing data not appropriately tackled. 45,56,57,[66][67][68]73,77 In the Early Self-Controlled Anticoagulation Trial, 70 the problem of incomplete outcome data was addressed for the first 600 participants but not for all included participants. …”

“…In six trials, both the randomisation process and the allocation concealment were judged as 'unclear' due to the lack of adequate information. 45,56,59,[77][78][79] Attrition bias…”

“…55 Warfarin was the choice of vitamin K antagonist therapy in half of the included trials. 45,55,56,58,62,[64][65][66][67]69,71,73,74,78 In seven trials, participants were taking phenprocoumon and/or acenocoumarol and/or fluindione 57, 61,63,68,72,76,77 and, in one trial, participants received either warfarin or phenprocoumon. 75 In the remaining four trials, the type of vitamin K antagonist therapy was not reported.…”