Electronic "Quality Control" (EQC): is it just for unit use devices?

The US Clinical Laboratory Improvement Amendments of 1988 (CLIA'88) mandated daily quality control (QC) for all laboratory tests. CLIA'88 clearly envisioned traditional, matrix-based controls. However, recent interpretations allow routine use of "electronic" controls (EQC). These surrogate controls, reference cassettes, glass filters, electronic signals, etc., evaluate the photometric, electronic and computational components of the test system. EQC does not evaluate chemical reactions, sample and reagent manipulations, etc. When compared to traditional concepts, it represents a discontinuity in logic and subverts the fundamental purpose of QC. The advent of "unit-use" test systems (reagent packs, cassettes, cartridges, etc.) used primarily in decentralized testing locations opened the door to EQC. The rationale behind EQC is that if the test system is operating within specifications and the manufacturer reliably delivers consistent and uniform quality products, a simple electronic check will assure that the entire testing process is in control. Unrecognized test system failure is the most insidious problem facing today's instruments using EQC-based systems. We cite positive and negative examples. We also ask, "If EQC is accepted, from a regulatory perspective for some instruments, why not for all?" Is the next step universal EQC, for all systems, inevitable?

Early diagnosis of cystic fibrosis through neonatal screening prevents severe malnutrition and improves long-term growth. Wisconsin Cystic Fibrosis Neonatal Screening Study Group.

OBJECTIVE: Despite its relative frequency among autosomal recessive diseases and the availability of the sweat test, cystic fibrosis (CF) has been difficult to diagnose in early childhood, and delays can lead to severe malnutrition, lung disease, or even death. The Wisconsin CF Neonatal Screening Project was designed as a randomized clinical trial to assess the benefits and risks of early diagnosis through screening. In addition, the incidence of CF was determined, and the validity of our randomization method assessed by comparing 16 demographic variables. METHODOLOGY: Immunoreactive trypsinogen analysis was applied to dried newborn blood specimens for recognition of CF risk from 1985 to 1991 and was coupled to DNA-based detection of the DeltaF508 mutation from 1991 to 1994. Randomization of 650 341 newborns occurred when their blood specimens reached the Wisconsin screening laboratory. This created 2 groups-an early diagnosis, screened cohort and a standard diagnosis or control group. To avoid selection bias, we devised a unique unblinding method with a surveillance program to completely identify the control subjects. Because sequential analysis of nutritional outcome measures revealed significantly better growth in screened patients during 1996, we accelerated the unblinding and completely identified the control group by April 1998. Having each member of this cohort enrolled and evaluated for at least 1 year and having completed a comprehensive surveillance program, we performed another statistical analysis of anthropometric evaluated indices that includes all CF patients without meconium ileus. RESULTS: The incidence of classical CF, ie, patients diagnosed in this trial with a sweat chloride of 60 mEq/L greater, was 1:4189. By incorporating other CF patients born during the randomization period, including 2 autopsy diagnosed patients and 8 probable patients, we calculate a maximum incidence of 1:3938 (95% confidence interval: 3402-4611). Although there were group differences in the proportion of patients with DeltaF508 genotypes and with pancreatic insufficiency, validity of the randomization plan was demonstrated by analyzing 16 demographic variables and finding no significant difference after adjustment for multiple comparisons. Focusing on patients without meconium ileus, we found a marked difference in the mean +/- standard deviation age of diagnosis for screened patients (13 +/- 37 weeks), compared with the standard diagnosis group (100 +/- 117). Anthropometric indices of nutritional status were significantly higher at diagnosis in the screened group, including length/height, weight, and head circumference. During 13 years of study, despite similar nutritional therapy and the inherently better pancreatic status of the control group, analysis of nutritional outcomes revealed significantly greater growth associated with early diagnosis. Most impressively, the screened group had a much lower proportion of patients with weight and height data below the 10th percentile throughout childhood. CONCLUSIONS: Although the screened group had a higher proportion of patients with pancreatic insufficiency, their growth indices were significantly better than those of the control group during the 13-year follow-up evaluation and, therefore, this randomized clinical trial of early CF diagnosis must be interpreted as unequivocally positive. Our conclusions did not change when the height and weight data before 4 years of age for the controls detected by unblinding were included in the analysis. Also, comparison of growth outcomes after 4 years of age in all subjects showed persistence of the significant differences. Therefore, selection bias has been eliminated as a potential explanation. In addition, the results show that severe malnutrition persists after delayed diagnosis of CF and that catch-up may not be possible. We conclude that early diagnosis of CF through neonatal screening combined with aggressive nutritional therapy can result

Effect of legislation (CLIA'88) on setting quality specifications for US laboratories.

The Clinical Laboratory Improvement Amendments of 1988 (CLIA'88) mandated, in response to concern over the perceived quality of clinical laboratory testing, universal regulation for all testing sites in the USA, including previously unregulated sites in physician offices. The intent of CLIA'88 is to ensure quality of testing through a combination of total quality management and mandated minimum quality practices. CLIA also defines, intentionally or unintentionally, through its proficiency testing requirements, intralaboratory performance standards. Meeting these requirements has been a prime motivator in improving laboratory performance. Seven years after the implementation of CLIA'88, the percentage of laboratories passing proficiency testing has increased and most laboratories have implemented quality practices.

Application of the Department of Health and Human Services proposed waived status requirements for in vitro diagnostic testing devices: case study.

The CLIA'88 classified all clinical laboratory testing as waived, moderate, or high complexity. The eight original waived tests were characterized as simple, accurate, error-free, risk-free, and suitable for home use by non-laboratory professionals. The subjective nature of the classification process was challenged immediately. The Clinical Laboratory Improvement Advisory Committee asked the CDC and the Health Care Financing Administration to develop objective criteria that included assessment of performance by field-test and in-house data. We examined the efficacy of the CDC protocol with empirical data from the HemoCue B-Hemoglobin Test System submission, to assess operator competency, intra-/interoperator and between-site imprecision, and accuracy. Non-laboratory-trained operators demonstrated 2-3% imprecision (40-200 g/L). Accuracy studies yielded a slope of 1.01, an intercept of 3.53 g/L, and r of 1.00 (52-230 g/L). Results met the protocol's Tonks' criterion for imprecision (less than one-fourth of the reference range).

Quality: the next six months.

The eclectic mix of participants in the forum had a surprisingly singular focus when it came to the topic of quality in clinical laboratories. All sensed that the time is right for a transition from laws, rules, and inspections to a true quality-based system. Such a system can achieve the goals, implicit and explicit, that are the rationale for the multiplicity of regulations affecting today's laboratories. A true quality-based system has great potential benefits to laboratories, regulators, and manufacturers, and ultimately to our true customers, the patients. The benefits include lower costs, superior products, and better test results; in short, better patient care. This transition will be possible only through formation of a "Quality Alliance," composed of those skilled in the "theory" of quality-laboratory personnel, manufacturers, and regulators, acting as one to implement the quality system. The Quality Alliance requires a team of individuals with different skills, aligned as one, for the purpose of achieving a common goal. On the basis of views expressed in this Forum, our collective future will be defined by the evolving Quality Alliance, an alliance focused on true quality systems in clinical laboratories.

Regulatory requirements (CLIA '88, JCAHO, CAP) for decentralized testing.

All decentralized testing is regulated according to the Clinical Laboratory Improvement Amendments of 1988. Two organizations, the Joint Commission on Accreditation of Health Care Organizations and the College of American Pathologists, have received deemed status for their voluntary standards from the Health Care Financing Administration. Deemed status means that the organizations' voluntary standards meet or exceed the federal requirements. The decentralized testing sites can exercise several options in determining which organization, and hence which set of standards, will be used to regulate their testing processes. In this article, the authors outline the various regulatory requirements, provide insight into the relationship of each, and offer a framework for decentralized testing sites to follow to meet the requirements.

Newborn screening for cystic fibrosis in Wisconsin: first application of population-based molecular genetics testing.

Infants born in Wisconsin are being screened for cystic fibrosis (CF) associated with the F508 mutation. This screening program has been developed during 9 years of research supported by the National Institutes of Health and involves a unique, two-tier system employing measurement of immunoreactive trypsinogen (IRT) initially. When the IRT level is high, DNA is extracted from the neonatal dried blood specimen and analyzed for the F508 mutant allele, following polymerase chain reaction (PCR) amplification; the F508 mutation is present in more than 90% of CF patients and accounts for the common, severe form of the disease. Infants with a positive DNA test are either CF heterozygote carriers or CF patients, depending on the results of a sweat test, which should be performed at 4 weeks of age. Screening the newborn population for CF provides the opportunity for early nutritional and respiratory interventions, as well as genetic counseling. This represents the first population-based application of molecular genetics for detection of a major congenital disorder causing serious public health problems. The process by which the recommendation was reached to screen for CF is described in this article, along with new information on the pathogenesis of CF, its clinical presentation, the rationale for newborn screening, and the method developed for the screening program.

Comparison of plastic vs. glass evacuated serum-separator (SST) blood-drawing tubes for common clinical chemistry determinations.

We evaluated a plastic evacuated blood-drawing tube containing an integral serum-separating barrier gel, by direct comparison with a glass counterpart. The plastic tube demonstrated no differences when compared for common clinical chemistry analytes with multiple types of instruments and systems. A total of 260 such different combinations were studied with emphasis on tests sensitive to drawing and handling indexes such as lactate dehydrogenase and potassium. A total of six separate blood drawings were tested with no significant differences noted in these tests. The total study included subjective evaluations of the plastic tube's use as a blood-drawing device and objective studies based on quantitative test results from normal and hospitalized patients and use of the primary sampling tubes (both plastic and glass) for 48-h storage.

Health Care Financing Administration's new proficiency testing rules. Use of a statistical approach to predict long-term performance using the categories 'successful,' 'probation,' and 'suspended'.

Under the Clinical Laboratory Improvement Act of 1967 (CLIA-67) and the Medicare Act, the Health Care Financing Administration's proficiency testing rules apply uniformly to all hospital and reference laboratories. We examined the relationship between internal laboratory performance as characterized by bias and coefficient of variation and proficiency testing performance, categorized as "successful," "probation," and "suspended." Under the March 14, 1990, final rule, a laboratory with suspended testing for even one analyte may be required to cease testing in the entire subspecialty, eg, routine chemistry, unless it ceases testing for that analyte. Analyzing this regimen as a Markov process, we obtained the steady-state solution for performance for one to 27 analytes. While 1.1% of laboratories testing for five analytes with internal or day-to-day coefficients of variation at 50% of the CLIA-67 proficiency testing limit would be suspended, 19.5% of laboratories having biases of 50% and coefficients of variation of 33% would be suspended. We conclude that after eight events, there will be an unacceptably high rate of suspensions.

Limitations of proficiency testing under CLIA '67.

Proficiency testing (PT), recognized as a quality-assurance (QA) and quality-improvement tool, also has become the cornerstone of the Health Care Financing Administration's (HCFA) regulatory strategy under the revised Clinical Laboratory Improvement Act of 1967 (CLIA '67) and the proposed Clinical Laboratory Improvement Amendments of 1988 (CLIA '88). Use of PT as a regulatory tool corrupts it for things it can do better. PT as a primary regulatory strategy has severe limitations. We explore the nature of these limitations and their implications for clinical laboratories as they impact on the long-term success of HCFA's approved regulatory PT programs in 1991 and beyond, and CLIA '88 PT, which is to be implemented in 1994.

Review of actual proficiency-testing performance under CLIA '67 (March 14, 1990) rules: perspective from the first year's data.

Under the Clinical Laboratory Improvement Act of 1967 the Health Care Financing Administration's proficiency-testing requirement applies to approximately 12,000 hospital, reference, and large-clinic laboratories in the United States. The Wisconsin State Laboratory of Hygiene is approved by the Health Care Financing Administration to provide proficiency testing in all specialties and subspecialties. The focus of the program is to provide highly specialized service and support to a limited number of participants in order to assess intralaboratory performance correctly. We report the findings over the four proficiency-testing events in 1991 for the subspecialty of routine chemistry, which serves approximately 470 participants. Failure rates for individual analytes on single proficiency testing events ranged from 0% to 13%. After four events or one year, if the mandated evaluation criteria and failure rules were strictly applied, as many as 11% of the laboratories could have found themselves involuntarily suspended from offering all routine chemistry testing.

The effect of dentures and denture adhesives on mouth alcohol retention.

A total of 24 alcohol-free, denture-wearing subjects were tested for mouth-alcohol retention times with an Intoxilyzer 5000. The subjects were given 30 mL doses of 80 proof brandy to swish in their mouths without swallowing for 2 min prior to expectorating the dose. Subjects were tested under three conditions: 1) with dentures removed, 2) with dentures held loosely in place without an adhesive, and 3) with dentures plus an adhesive. Beyond 20 min following expectoration, mouth alcohol made no significant contribution to the apparent breath alcohol concentration (BrAC), with trace (less than or equal to 0.01 g/210 L) readings found in only two of the subjects. Denture use, both with and without the concurrent use of adhesives does not significantly affect BrAC as long as a pretest alcohol deprivation period of 20 min is observed.

Intralaboratory performance requirements necessary to pass proficiency testing: CAP-1990 vs CLIA-1967 (March 14, 1990) formats compared.

The pre-1990 College of American Pathologists' (CAP) Proficiency Testing (PT) program used a two samples per analyte/four challenges per year format with performance or pass-fail grading criteria determined by the program. On Jan. 1, 1991, the Clinical Laboratory Improvement Act of 1967 (CLIA-67) final rules (March 14, 1990) mandated a revised PT format of five samples per analyte/four challenges per year, with the regulations specifying minimum performance criteria. Extending our previous analysis, we compare the maximum permissible intralaboratory imprecision at low bias compatible with passing external PT in the former CAP and current CLIA-67 formats. If a laboratory is able to reduce its internal coefficient of variation (CV) to less than 44% of the PT criterion for each analyte, its overall chance of adverse action for any of the 27 routine chemistry analytes specified in CLIA-67 will be less than 1% in a two-year (eight PT challenges or events) period. Consideration of actual interlaboratory CVs from CAP surveys suggest that a reduction of this magnitude may be difficult for the analytes total cholesterol and blood urea nitrogen, where intralaboratory imprecision comparable with the group standard deviation (SD) from 1990 CAP surveys would yield individual adverse action (PT failure) rates of 5% and 1%, respectively. Five other analytes have CLIA-67 performance limits dangerously close to CAP interlaboratory CVs.

Are clinical laboratory proficiency tests as good as they can be?

Present proficiency test services that use the peer group mean and statistically derived ranges of acceptability are not serving us optimally and are even counterproductive in some respects. We recommend that the target value be determined by a widely accepted reference method and that acceptable ranges be based on criteria related to clinical need. This approach was adopted several years ago in Germany and has already eliminated the use of several unsatisfactory analytical methods. Because the transition would probably take many years, we propose an interim solution to allow instrument manufacturers and laboratorians to adapt to these changes. The current peer group means and acceptable ranges should be supplemented by reference method values and acceptable ranges, based on clinical need, so that manufacturers and laboratorians can judge their performance against these new criteria and make the necessary adjustment in instrumentation and methodology. These processes should be paralleled by efforts to produce proficiency test materials that will not exhibit the matrix problems of present-day preparations.

Current issues in neonatal screening for cystic fibrosis and implications of the CF gene discovery.

Many questions remain regarding the efficacy, toxicity, and costs of CF neonatal screening. It would be premature, in our opinion, to implement mass population screening of newborns for CF until the benefits and risks have been fully defined, and an adequate and logistically feasible testing system developed and/or highly effective therapy for CF lung disease becomes available. In addition, the ethical issues described herein need to be resolved. This pertains not only to the CF patient but also the heterozygote carrier. These reservations notwithstanding, the discovery of the CF gene should have a favorable impact both directly and indirectly on neonatal screening for the disease. Mutation analysis coupled to IRT testing seems most attractive at this time, at least on a research basis, but primary molecular diagnostic procedures might supervene in the future, particularly if they are financially feasible.

Laboratory quality control issues related to screening newborns for cystic fibrosis using immunoreactive trypsin.

We have incorporated the IRT assay for CF to our newborn screening program, relying heavily on electronic data processing to optimize the test results in order to provide the most reliable data possible from the specimen at hand. We have established an internal cut-off of 100 ng/mL and an external referral of 180 ng/mL; this virtually eliminates the possibility that analytical imprecision will result in misidentifying a positive patient specimen. The relationship between IRT levels and various mutant forms of CF are not well established, and it is possible that various forms of CF may exhibit different levels of IRT in the first few days of life. We believe that IRT screening for CF could be a useful procedure for early identification of potential CF. However, by comparison with other newborn screening tests, its sensitivity, 90%, presents a concern. The expectation for PKU, hypothyroidism, MSUD, and galactosemia screening is 100% sensitivity. A false-negative usually results in litigation. The use of IRT in routine newborn screening will require considerable education of the general public and physicians receiving test results. Our program, along with many others, is anxiously watching the developments in the area of gene testing. We feel the relatively inexpensive IRT, used for mass screening can be successfully coupled with the more definitive (and expensive) gene test on a selected population to identify CF at the earliest possible age in a more effective manner. It is possible that in the near future gene probe tests will be applied in a cost effective manner to the initial filter paper specimen.

1990 Medicare/CLIA final rules for proficiency testing: minimum intralaboratory performance characteristics (CV and bias) needed to pass.

On March 14, 1990, the Centers for Disease Control and the Health Care Financing Administration published criteria for defining minimum performance in proficiency testing (PT). Using our previously described computer modeling technique, we determined the likelihood of passing PT under the new rules. The model relates combinations of intralaboratory CV and bias to PT performance criteria. For example, a laboratory with a bias of zero and an internal CV of 5% will pass a 10% fixed-limit PT criterion (i.e., the criterion for glucose analyses) 98% of the time when five samples are used. The model provides similar analyses for all PT criteria and all relevant combinations of CV and bias. The probability of passing PT decreases as the number of analytes tested increases, i.e., from 98% to 37% as the number of analytes increases from 1 to 20. A laboratory's internal CV has a greater effect on the outcome of PT than do the corresponding bias values. We conclude that a laboratory that operates with methods that have internal CVs less than or equal to 33% and biases less than or equal to 20% of the PT criteria will have a greater than 99% chance of passing PT.

Field performance of the Intoxilyzer 5000: a comparison of blood- and breath-alcohol results in Wisconsin drivers.

Intoxilyzer 5000 and blood-alcohol results from drivers arrested for operating a motor vehicle while intoxicated and for related offenses were compared during a two-year period. Three hundred and ninety-five pairs of results were studied. The breath- and blood-alcohol specimens in this study were collected within 1 h of each other. The mean blood-alcohol concentration obtained was 0.180 g/dL, with a range from zero to 0.338 g/dL. By comparison, the mean Intoxilyzer 5000 result was 0.16 g/210 L with a range from zero to 0.32 g/210 L. Compared with the blood-alcohol result, Intoxilyzer 5000 results were lower by more than 0.01 g/210 L 67% of the time, within 0.01 g/210 L 31% of the time, and higher by more than 0.01 g/210 L 2% of the time.

Newborn screening for cystic fibrosis is complicated by age-related decline in immunoreactive trypsinogen levels.

Detection of elevated levels of immunoreactive trypsinogen (IRT) in dried neonatal blood spots has been used as a screening test for cystic fibrosis. In other cystic fibrosis newborn-screening studies, a sweat chloride test is generally performed only if an infant has a persistent IRT level above a selected cutoff value on both the initial and subsequent specimens. Neither the timing of the second specimen nor the value of the cutoff point for the second specimen has been comprehensively evaluated. In this randomized, controlled study, 145,024 infants were screened in the neonatal period for cystic fibrosis using the 99.8 percentile (180 ng/mL) as the neonatal cutoff point. A total of 129 infants had elevated neonatal IRT levels and had negative results on sweat tests (false-positive by IRT screening). A total of 54 children with cystic fibrosis were identified in the screened and comparison groups. Excluding patients with meconium ileus, 4 infants with cystic fibrosis had neonatal IRT values less than 180 ng/mL, and an additional 9 infants with cystic fibrosis had values decline to less than 180 ng/mL within the first 2 1/2 months of age. The IRT values of infants with and without cystic fibrosis overlapped considerably beyond 30 days of age. These findings suggest that further refinement of cystic fibrosis screening methodology will be necessary to achieve an acceptable sensitivity and specificity.