Efficacy of Point-of-Care for INR Testing Compared to Standard Laboratory Methods at a Tertiary Care Hospital in Saudi Arabia

Abstract

Introduction Regular testing of the international normalized ratio (INR) is essential for people taking vitamin K antagonists as part of anticoagulation therapy. This study was undertaken to ascertain the efficacy of point-of-care testing (POCT)-INR versus conventional core laboratory testing in terms of result adequacy, waiting-time reduction, and patient satisfaction enhancement at the thrombosis clinic of the outpatient Medical Specialties Department in King Fahad Medical City, Saudi Arabia. Methods The study was conducted prospectively for 6 months (from June 2017 to December 2017) on 182 eligible participants out of 250 entitled patients who were attending the thrombosis clinic for warfarin dose adjustment and who fulfilled all the prerequisites for performing dual testing by fingerstick at the clinic and venipuncture by the core laboratory. The data-capturing template created on Microsoft Excel recorded turnaround times (TATs), clinical concordance of INR result variables by POCT, and laboratory methods. Individual patient experience was recorded to gauge satisfaction rate, and all the data were analyzed statistically. Results Of 182 patients included in the study, overall good concord was observed between POCT whole blood and laboratory plasma INR results with median bias of 0.07 and 92.3% agreement using acceptability criteria for clinical concordance of Clinical Laboratory Standards Institute (CLSI) 14-A and International Standards Organization (ISO) 17593-2007, respectively. Marked improvement in terms of patient's time spent at the clinic was noted, with substantial reduction from 180 to ∼30 minutes (p < 0.001). Survey questionnaire responses indicated that POCT of INR was highly convenient and enhanced patient experience in terms of shorter wait time, minimal invasive procedures, and immediate result availability (p < 0.001). Predominantly, participants (75.4%) endorsed and expressed a strong preference for the POCT procedure over conventional laboratory testing. Conclusions Whole blood INR testing for warfarin dose adjustment with validated POCT devices is adequately comparable to the core laboratory results. It also simplifies workflow steps at the thrombosis clinic, enhancing patient experience and convenience via the immediate availability of results, a less invasive procedure, and a marked reduction in waiting time. However, caution is needed with regard to higher INR results (≥4.7), which call for core laboratory confirmation.

Position Statement on in-hospital/clinic point-of-care coagulation testing for anticoagulation monitoring in Saudi Arabia

“…This was confirmed in a published local Saudi; results indicated that caution is needed with regard to higher INR results (>4.7), which call for core laboratory confirmation [ 61 ]. It is therefore essential to know the limitation of the POCT method in order to generate safe guidelines for clinical practice.…”

“…Moreover, experience with POC INR testing remains rather limited in Saudi literature. One study compared the efficacy of POC INR testing to standard laboratory measurement at a tertiary care hospital [ 45 ]. Results showed that POCT with validated results is comparable to conventional testing methods while simplifying clinic workflow, enhancing the patient experience and convenience (reduced waiting time, immediate result availability) and providing a less invasive alternative.…”

“…In the out-patient setting in case of busy anticoagulation clinic (i.e. limited time and staff, more than 24 h from blood sample collection till INR results); the use of POCT can reduce waiting time, improve the efficacy of clinical services and ensure patients receive the appropriate treatment for their condition in a timely manner [ 45 – 47 ].…”