Email this page
Print this page
Findings from a recent Center survey indicate a clear correlation between participation in proficiency testing, which is not currently required for genetic testing, and test quality. While proficiency testing is key to cutting errors, many genetic testing laboratories do not conduct proficiency testing (PT) for all the tests they offer, the survey reveals. The results appear in the September 2006 issue of Nature Biotechnology.
PT is distinguished from other quality assurance methods in that it tests the ability of laboratories to report the correct answer when analyzing a specimen. An outside entity can test a laboratory’s proficiency by sending it a sample and verifying that it returns a correct test result. Laboratories also may conduct informal PT by, for example, splitting a sample and performing the same test twice in order to see whether identical conclusions are reached.
“Few empirical data exist on genetic testing laboratory errors and testing quality, and no data have been made available that directly assess the relationship between the extent of participation in formal and informal PT programs and the types or frequency of genetic testing errors,” the authors note. To obtain such data, the Center drew from various sources to compile a list of laboratories in the United States that perform health-related genetic tests and report results to patients or providers. The Center asked the directors of these laboratories to complete a 65-question online survey, and received nearly 200 eligible responses (a 55 percent response rate).
Directors were asked about the types of tests they performed, the volume, estimated number of errors and types of errors, and PT. The survey also asked whether the labs were certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA); 95 percent were, and all of the exceptions were very low-volume laboratories. Many labs enrolled in formal, external PT programs where they were available, and conducted informal PT for tests with no formal program. However, more than a third of the laboratories performed no PT at all for at least one test they offered, including 44 percent of the highest-volume labs. Those laboratories that did not perform PT for every test type were eight times more likely to report multiple deficiencies – that is, they returned an incorrect result or analysis when analyzing a specimen more than once. Directors were asked to estimate the number of incorrect test reports their laboratories had returned in the past year; those estimates increased significantly for each deficiency the labs received.
The survey also asked about the types of errors laboratories experienced. These errors were categorized as pre-analytic (e.g., contamination or mislabeling of a specimen before the laboratory received it), analytic (e.g., human error in data analysis or equipment failure), and post-analytic (e.g., misinterpretation of data or typographical error on test report). A high level of PT participation dramatically decreased the probability that a laboratory’s most common error was analytic, the Center found.
PT could be mandated for genetic tests if a genetic testing specialty were enacted under CLIA, the authors say. Such a specialty would establish specific requirements beyond the basic CLIA guidelines for laboratories performing genetic testing. The survey indicates that the genetic testing industry would not find such a change onerous: nine out of 10 laboratory directors surveyed regard PT as useful for improving the quality of the genetic testing performed by the laboratory industry, and almost no one said cost is a driver of nonparticipation in programs. Seventy-three percent of respondents agreed or strongly agreed with the statement “CLIA should create a genetic testing specialty for molecular and biochemical tests.”
“The significant rates of nonparticipation in PT reported by directors of laboratories of all sizes demonstrates that merely being certified under CLIA is insufficient to ensure quality: a third of respondents reported that their laboratories did not perform PT for all of their tests,” the authors observe. “We conclude that the creation of a genetic testing specialty and the associated requirement to enroll in specified CLIA-approved PT programs would improve the quality of genetic testing laboratories.”
Full citation:
Hudson K, Murphy J, Kaufman D, Javitt G, Katsanis S, and J. Scott. "Oversight of US Genetic Testing Laboratories" Nature Biotechnology (2006) 24 (9): 1083-1090.
