MP14: Community paramedic point of care blood analysis: validity and usability testing of two commercially available devices

Abstract

Introduction: Community Paramedics (CPs) require access to timely blood analysis in the field to guide treatment and transport decisions. Point of care testing (POCT), as opposed to traditional laboratory analysis, may offer a solution, but limited research exists on CP POCT. The objective of this study is to compare the validity of two POCT devices (Abbott i-STAT® and Alere epoc®) and their use by CPs in the community. Methods: In a CP programme responding to 6,000 annual patient care events, a split sample validation of POCT against traditional laboratory analysis for seven analytes (sodium, potassium, chloride, creatinine, hemoglobin, hematocrit, and glucose) was conducted on a consecutive sample of patients. The difference of proportion of discrepant results between POCT and laboratory was compared using a two sample proportion test. Usability was analysed by survey of CP experience, an expert heuristic evaluation of devices, a review of device-logged errors, coded observations of POCT use during quality control testing, and a linear mixed effects model of Systems Usability Scale (SUS) adjusted for CP clinical and POCT experience. Results: Of 1,649 CP calls for service screened for enrollment, 174 had a blood draw, with 108 patient care encounters (62.1%) enrolled from 73 participants. Participants had a mean age of 58.7 years (SD16.3); 49% were female. In 4 of 646 (0.6%) individual comparisons, POCT reported a critical value that the laboratory did not; with no statistically significant difference in the number of discrepant critical values reported with epoc® compared to i-STAT®. There were no instances of the laboratory reporting a critical value when POCT did not. In 88 of 1,046 (8.4%) individual comparisons, the a priori defined acceptable difference between POCT and the laboratory was exceeded; occurring more often in epoc® (10.7%;95%CI:8.1%,13.3%) compared to i-STAT® (6.1%;95%CI:4.1%,8.2%)(p=0.007). Eighteen of 19 CP surveys were returned, with 11/18 (61.1%) preferring i-STAT® over epoc®. The i-STAT® had a higher mean SUS score (higher usability) compared to the epoc® (84.0/100 vs. 59.6/100; p=0.011). Fewer field blood analysis device-logged errors occurred in i-STAT® (7.8%;95%CI:2.9%,12.7%) compared to epoc® (15.5%;95%CI:9.3%,21.7%) although not statistically significant (p=0.063). Conclusion: CP programs can expect valid results from POCT. Usability assessment suggests a preference for i-STAT.