Quality Error Rates in Point-of-Care Testing

Point-of-care testing (POCT) represents one of the fastest growing segments of the diagnostics market. Although major advances have been made in the instrumentation and methods used for POCT, further development and enhancements appear to be necessary to meet the challenges presented by the difficult testing environments in which these devices are used. In addition, the varied experience and training of users and their use of samples that may not be optimal for testing continue to present challenges in the implementation of POCT (1 ). One of the major advantages of POCT is that it provides much faster access to test results, allowing for more rapid clinical decision making and moreappropriate treatments and interventions. In addition, POCT can help minimize time-dependent changes in labile analytes such as lactate and glucose, which can be caused by delays in sample transport to the clinical laboratory. Finally, many POCT methods require much smaller sample volumes than those needed for testing in the central clinical laboratory. Preventing medical errors has become a major focus of quality improvement in healthcare. Most errors that occur in the clinical laboratory setting take place during the preand postanalytical phases of the testing process, and several studies have documented the types and frequencies of the errors that can occur (2 ). In addition to the benefits mentioned above, the use of POCT may help reduce the frequencies of some of these errors, such as the preanalytical errors associated with inappropriate sampling, inappropriate preparation or packaging of samples, and misidentification of patients (3 ). In addition, the decrease in the number of steps necessary to produce a test result associated with POCT should help reduce the potential for errors to occur. Moreover, the fact that POCT is often performed by the individual providing care to the patient may help decrease postanalytical errors due to incorrect transmission of test results; however, implementation of clinical-management decisions immediately on receipt of POCT results can increase the risk to the patient if any of the results are in error, because errordetection schemes such as automatic delta checking are typically not used in these settings. Although POCT may lead, in theory, to decreases in certain types of errors, little information exists concerning the error rates associated with POCT itself. The study performed by O’Kane et al. and reported in the current issue of the Journal is noteworthy for the large number of different POC tests that were evaluated and the relatively long time period over which the study was performed (4 ). These investigators evaluated a variety of POC tests over a 14-month period, including blood gases and electrolytes, urine human chorionic gonadotropin, hemoglobin A1c, blood glucose, blood ketones, drugs of abuse, and urine dipstick analysis. The study was performed in 2 acute care hospitals and 1 non–acute care hospital. Errors were classified by cause and graded according to the actual harm caused to the patient because of the error, as well as the potentially worst harm that the error could have caused. A culture of openness that focused on improving the POCT system rather than apportioning individual blame was promoted as the mechanism for assuring the identification of weaknesses in processes and procedures in the POC setting. Although the actual impact of POCT errors was considered minimal, with 51.8% of errors considered to have no impact on patient care and 48.2% considered to have minimal impact on patient care, a review revealed that the potential impact of these errors was much higher, with 14.7% and 3.6% of the errors considered to have the potential to produce moderately or substantially adverse patient outcomes, respectively. In contrast to errors seen in the clinical laboratory setting, where the vast majority of errors occur in the preanalytical and postanalytical phases of testing, the study of O’Kane et al. shows, interestingly, that two thirds of the errors occurred in the analytical phase of the testing process. The authors indicate that such preanalytical factors as altered sample integrity (e.g., hemolysis, lipemia, icterus, and so on) that would be identified and considered as causes of preanalytical error in the laboratory setting where serum or plasma samples are tested, often go unrecognized in POCT systems that use a whole-blood sample or do not have a defined mechanism for assessing sample integrity. Thus, the actual error rates reported in this study for POCT could 1 Department of Pathology, Oregon Health and Science University, Portland, OR. * Address correspondence to the author at: Department of Pathology, Oregon Health and Science University, Mailcode L-471, 3181 SW Sam Jackson Park Rd., Portland, OR 97239. Fax 011-503-494-8148; e-mail [email protected]. Received June 29, 2011; accepted June 30, 2011. Previously published online at DOI: 10.1373/clinchem.2011.171538 2 Nonstandard abbreviations: POCT, point-of-care testing; EQA, external quality assessment. Clinical Chemistry 57:9 000 – 000 (2011) Editorials