Testing-testing: You want fries with that INR?
This is a superficial post on point-of-care (POC) testing touching on general background info. This topic and especially “Lab On A Chip (LOC)” has been addressed several times by Dr. Friedman in LabSoftNews (see links tab to the right).
Over a dinner of delicious home-cooked food, my mother, in a perpetual exercise to understand the scope of exactly what it is a pathologist does, asked me on my last visit home about laboratory testing. She wondered how her cousin, who is a high school graduate, could be involved with medical laboratory testing–including DNA test handling–without additional training. As I am not a laboratory manager and still consider myself a somewhat green resident (Will this feeling ever go away?), my first response was “?”.
It is clear that my mother’s cousin is probably performing or responsible for CLIA-waived tests, which have no routine oversight and no personnel requirements.1 The lab is only required to obtain a certificate of waiver and pay the renewal fees on this certificate and follow manufactures test instructions when performing tests.1 According to the Clinical Laboratory and Improvement Amendment of 1988 (CLIA), tests are classified according to complexity, and the categories are as follows: waived tests, tests of moderate complexity, and tests of high complexity.2 There are seven criteria where a test will receive a score from 1 (low complexity) to 3 (high complexity), and a score of 12 or more is a high complexity test.2 The general criteria are: knowledge, training/experience, reagents, characteristics of operational steps, calibration and quality control, test system trouble shooting and equipment maintenance, and interpretation and judgement.2
Specimen types fall under the general category of unprocessed specimens: whole blood, throat swab, nasal wash/swab, saliva, oral fluid, urine, stool, and gastric biopsy (for H. pylori). Approximately 1,600 test systems, representing at least 76 analytes, are waived under CLIA.1 Sites performing only waived tests comprise 58% (105,138) of the approximately 180,000 laboratory testing sites in the United States.1 Tables of proportion of labs performing waived tests are below.
From 1999 to 2004, the Center for Medicare and Medicaid Services (CMS) conducted multiple quality surveys on CLIA-waived labs to study the client base, personnel make up, and factors contributing to error.1 Quality deficits were mainly attributed to failure to follow manufacturers’ instructions or failure to identify incorrect results and performing unauthorized testing.1 There was also a high turn over rate for testing employees.1 As a result, recommendations were released in 2005 for best practices for these CLIA-waived laboratories. A test is considered a POC test if it is a laboratory test performed and the results rendered at the location where the patient is receiving care, whether it be at the bedside, in the emergency department, at a physicians office, or at home (self monitoring, bhCG). A POC test may be a CLIA-waived test like those described above, or a test with (usually moderate) complexity, depending on the test characteristics. Examples of POC tests in the hospital setting are glucose, iSTAT (limited chemistry panel, ABG etc), PT/INR, and ACT, to list a few. POC tests performed in accredited labs fall under the same regulations as all other tests.
POC INR tests for warfarin dosing have been compared to traditional lab PT tests and the results are varied. Some studies show excellent correlations with lab results, while others show a high variability between different POC test platforms.3-8 However, the use of POC INR tests can smoothen operations for anticoagulation clinics, where patient wait time decreases significantly, and as long as a stable test platform is used, dosing regimens and follow-up can become predictable with experience. Point of care testing is attractive in the emergency room and other settings where rapid test results are needed (e.g. intraoperative testing) because of the speed for clinical decision making, with improvements in time to decision-making ranging from 21 minutes for blood gases to 86 minutes for biochemical tests (Note: these are year 1998 minutes).9-10 Another recent advance in POC testing is integration with the electronic medical record in the hospital, making tracking of test utilization and test results more accurate.11
Obviously, one could go on to write volumes about this topic, and it is well beyond my experience to do so with any appreciable depth. The future of POC testing will be interesting to watch, with technologies emerging in the literature which suggest an expansion of the panel of possible biomarkers (and PCR?) as well as bloodless saliva-based systems.12-14 Will this steady push to LOC extend into POC? (And possibly the most interesting question–What will the lab regulations entail? And what are the practical aspects of ensuring quality results for the best patient care?)
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Tables taken from reference 1.
References
1. MMWR Nov. 11, 2005/54(RR13); 1-25
2. http://www.fda.gov/cdrh/clia/#background
3. J Am Md Dir Assoc
4. Thromb Hemost 2000; May 83(5); 698-703
5. Blood Coagul Fibrinolysis 2007; APr 18(3);287-92
6. Can J Cardiol 2007; Jan 23(1):47-50
7. AJCP 2001; Feb 115(2):280-7
8. Br J Haremotl 2005; Jan 128(2):242-7
9. Ped Merg Care 2007; Jul 23(7): 457-62
10. BMJ 1998 Apr 316(7137):1052-1057
11. CAP Today, April 2006, Feature Article
12. LabChip 2004; Auf 4(4): 310-5
13. BioMed Microdevices 2006; Sep 8(3):215-25
14. Dent Clin North Am 2005; Jul 49(3): 551-71


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