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This paper reports results of a first phase of a pilot study to assess and improve quality of diagnoses in cervical cytological laboratories located throughout Italy. It represents the first phase of an External Quality Assurance programme (EQA). In the first phase, two sets of cervical smears representing a range of diagnoses were circulated among participating laboratories. Responses were recorded on a standardized form. Participants were asked to assess the adequacy of the smear and formulate a diagnosis. They were also asked to recommend management of the patient on the basis of the smear report and judge the degree of diagnostic difficulty of each slide. Crude index of agreement, unweighted and weighted kappas, diagnostic specific kappas, sensitivity and specificity as well as clinical indices of variability were calculated. In the second phase, two additional sets of slides were circulated after discussion of the first phase. There was striking variability between laboratories, both in terms of diagnoses offered and recommendations for management on individual slides. Assessment of the degree of difficulty of each slide was also very variable. Discrimination between CINII and CINIII was poor, confirming the choice of merging these two categories in the Bethesda classification. However, discrimination between CINI and CINII was also unsatisfactory. The results were discussed in workshops and it was possible to reach a consensus diagnosis in 35 of 40 smears. This study confirms the need for external quality control programmes.
OBJECTIVE: To investigate the adequacy of bedside glucose monitoring (BGM) quality control documentation and monitoring, characterize program structure and organization, and identify characteristics associated with the ability to produce accurate results. DESIGN AND SETTING: College of American Pathologists Q-Probes laboratory quality improvement study in 544 institutions. MAIN OUTCOME MEASURES: Percent compliance with quality control (QC) documentation, appropriate corrective action, and frequency of inappropriate patient testing, and the percentage of BGM results within +/-10% and +/-15% of a corresponding clinical laboratory glucose result. RESULTS: Five hundred forty-four institutions reviewed a total of 19543 individual QC paper documents from 2543 separate BGM instruments. Ninety percent of QC determinations that should have been performed and noted on these documents were recorded; of those performed, 2.8% of QC results were outside of the acceptable range. Thirty-two percent of the out-of-range QC results had no record of corrective action. There were 527 reported instances of one or more patients being tested when there was no record of corrective action for out-of-range QC results. There were 20665 undocumented potential QC events, with 2053 instances of one or more patients being tested when there was no documentation. Two hundred forty-two institutions submitted 6653 paired BGM and clinical laboratory results for comparison. Approximately 56% of BGM results were within +/-10%, and 74% were within +/-15% of the corresponding clinical laboratory result. Factors associated with better accuracy performance are discussed. CONCLUSIONS: There is a need for improving compliance with QC documentation, improving appropriate corrective action follow-through, decreasing the frequency of inappropriate patient testing, and improving BGM accuracy performance. We provide recommendations for improvement.
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A computer simulation program has been developed to aid clinical chemists in the design and theoretical evaluation of statistical control procedures. This "QC simulator" permits the user to study the effects of different parameters characterizing the measurement procedure (method standard deviation, components of variation, rounding of results) and parameters of the control procedure (decision criteria, control limits, number of observations). The performance of control procedures is characterized by the probability for rejection, estimated at several different levels of random and systematic error. Predictive values for reject and accept signals are also calculated at different error incident rates, given a specified error model. The relative performance of different control procedures can be compared based on these performance characteristics. Another important application of the program is the design of control procedures to assure that a specified level of analytical quality is achieved in routine analyses. Various optimization criteria may be applied, e.g., in terms of test yield and cost.
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Multirule quality control procedures employ combinations of individual quality control rules to increase the probability of error detection without increasing the probability of false rejections to unacceptable levels. Performance characteristics of several example multirule procedures are described, and general recommendations are made for their selection and use. Multistage quality control procedures tailor the control rules employed to the frequency of errors expected during a given phase of analyzer operation. During analyzer startup, sensitive rules are employed; after acceptable analyzer performance is demonstrated, less sensitive rules are used for routine monitoring. As they tend to deteriorate quality control rule performance, between-run variations should be minimized.
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The aim of our study is to verify the reliability, reproductiveness and simplicity of a method to control cardiac surgical results. We divided 462 adult patients, operated on for acquired heart disease from October 1989 to January 1991, into five classes according to an individual score which was predictive for their operative mortality risk. The score resulted from 15 different risk factors tested with univariate and multivariate analysis against one event: operative death. The total number of deaths was 12: 2, 2, 1, 2, 5 for each class respectively. When comparing the predicted versus our observed mortality, we found no statistically significant difference, using the chi-squared test. The method we used is highly predictive for surgical mortality risk: it makes the results objectively comparable among different institutions; it is useful as a self-controlled quality method for cardiac surgical activity in any single institution.
On a per capita basis, PTCA is more than three times more prevalent in the United States than in any other country. The US has nearly 1,000 institutions and 7,000 physicians doing angioplasty. Mortality and emergency bypass surgery rates are inversely proportional to angioplasty volume. Although PTCA is more prevalent in the United States, operators in other countries do more cases than do their US counterparts. Multiple forces control quality in the United States. Economic, political and legal forces are all important.
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A 10-laboratory collaborative effort was designed to generate data to propose quality control limits for susceptibility tests of trovafloxacin. Broth microdilution, agar dilution, and disk diffusion tests were evaluated with eight different control strains. All tests were reproducible, and control limits are proposed.
We report on the experience of establishing a national network for a quality control programme in evaluating CD4 cell counts in most Italian centres involved in the care of patients with HIV disease. The 68 centres were divided according to their geographical location into eight groups, and twice a year (tests A and B) they received three coded whole blood samples (two were replicates of the same sample) obtained from two informed HIV+ patients, one with CD4 counts/mm3 expected to be < 200 and one with values > 300. The medians of the determinations performed by the labs involved in each of the eight areas were taken as the 'true' values for each sample. Unsatisfactory performances for percentage of CD4 cells were identified as a CD4 analysis with residual values > or = +/- 5% and with deviates > or = +/- 2. For absolute numbers of CD4 cells, an unsatisfactory performance was defined as CD4 counts with residual > +/- 100 CD4 cells/mm3 and with deviates > or = +/- 2. The residual value is the CD4 value reported by each lab minus the median value. The deviate is the residual divided by the modified interquartile range (IQR x 0.75). Most of the centres provided reliable results. However, some labs failed to provide satisfactory results for percentages (6.25% of the tested labs for test A and 6.17% for test B) or absolute numbers (16.25% test A and 12.34% test B). Only 3.7% of the labs gave unsatisfactory results in both tests. Four of the unsatisfactory results from the two tests gave an error in absolute numbers > +/- 200 CD4 cells/mm3. Our data suggest that most Italian labs provide reliable results in evaluating the numbers of CD4 cells in HIV-1+ samples, but the importance of running a quality control programme is highlighted by our experience with those centres which provide unsatisfactory data which may lead to incorrect classification of the patients or assessment of treatment.
Standard controls for quality control of cell growth (proliferation) assays in image analysis systems are not currently available. The authors have developed a system of controls, based on cultured and harvested human cell lines, that can mimic tissue sections. These controls help ensure quality control for the entire cell proliferation analysis process, from the initial cutting of the paraffin block through fixation, immunohistochemical staining, and interactive image analysis. The use of cell line controls is advantageous because of the greater cell population homogeneity and the volume of uniform slides that are obtainable, as opposed to the use of a heterogeneous tissue sample. This system provides an excellent means of evaluating the day-to-day performance of cell proliferation analysis and may also be adapted for use as a method of multi-institutional proficiency testing.