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A Rosas-Baruch

Publications and source records attributed to A Rosas-Baruch.

4 recordsLinked to original sources
PubMedDate not supplied

External quality control program of four blood cell counters.

OBJECTIVE: To evaluate an internal-external quality control program of four automated counters. METHODS: Every one or two weeks during 14 months, six direct cell parameters were measured in three fresh blood samples in four Coulter counters. The median per parameter of the working day was used to detect inaccuracies and if the participants' internal control program confirmed it, a recalibration of the parameter was performed. RESULTS: In 21 of 22 instances, the internal program confirmed an inaccuracy and a recalibration was done (4 leukocyte and 5 erythrocyte counts, 5 hemoglobins, 7 red-cell volumes). In these four parameters there were no large differences between the lowest and highest counter upon analyzing all results whereas all counters differed from one another in the parameters that cannot be recalibrated by the user (platelet volume, red-cell distribution width). CONCLUSIONS: 1. The program contributed to good accuracy and precision within-counters and good concordancy between-counters in the parameters that can be recalibrated. 2. The counter differences in red-cell distribution width were sufficiently large (up to 9%) to affect clinical interpretation. This poses the need of width distribution reference ranges for each counter.

Blood Cell Count↗
PubMedDate not supplied

[Permanent clinical chemistry program of the National Institutes of Health. II. Sources of variation in 2 imprecise analyzers].

BACKGROUND: In a previous report of the program of interlaboratory concordancy in the MNIH (Mexican National Institutes of Health) we observed imprecision in nearly half of the analytes assayed by participants B and J. OBJECTIVES: 1. To identify possible sources of variation in the analyzers. 2. To take corrective actions and see their effect on precision. MATERIAL AND METHODS: Analyzer B had been operating for 2.5 years and analyzer J for more than ten years (Lab J switched to a new analyzer from a different supplier in the last three months of the study). Both participants submitted their daily results in commercial controls (normal and high). Lab J furnished results for a period of six months (Jul-Sep/92 using the old analyzer, and Oct-Dec using the new one) and Lab B reported five months (it used Jul to change its operating procedure). Lab B assayed 16 analytes (two electrolytes, four enzymes and ten organic analytes) and Lab J 17 (four electrolytes, four enzymes and nine organic). They also agreed to maintain a logbook of any change in calibrators, controls, reagents, analysts, or operating procedures. The information of the first two months was used in a multiple analysis of variance (MANOVA) using the control assays as the dependent variable, and the logbook notations as the independent variables. Precision was expressed as a monthly mean of means of CVs of all analytes. RESULTS: The MANOVA identified two sources of variation in analyzer B: 1) recalibrations (done fortnightly in an effort to improve performance); 2) control flasks. A restriction of calibrations led to an improvement in precision, i.e. from a CV of 5-7% in Aug-Sep to 3-4% in Oct-Dec. In the old analyzer of Lab J, the MANOVA was unable to identify causes of the high imprecision (CVs of 14-19% in Jul-Sep). With the new analyzer, precision improved (CV of 6% in Nov-Dec). Two observations of interest in the new analyzer were: a) a period of familiarization with the apparatus was apparently needed (CV was 11% in Oct); b) imprecision persisted in three analytes (CVs of 11-14% in BUN, calcium, and triglycerides in Nov-Dec). A second MANOVA in this lapse also failed to identify sources of variation for these three analytes. CONCLUSIONS: 1. Analyzer B is operating at an acceptable level of precision and can fully participate in our program. 2. The new analyzer of J can participate in the assays of 14 analytes.

Academies and Institutes↗
PubMedDate not supplied

[First two years of an external quality assurance program for urinalysis].

OBJECTIVE: To analyze the first two years of a strip uroanalysis quality assurance scheme operating in Mexico. METHODS: The participants received 8 shipments of four controls each as dried tablets to be dissolved and analyzed with urine strips. The number of participants increased from < 50 in the 1st shipment to > 200 in the 8th. They assayed 6-10 analytes depending on the strip used and sent in 763 reports. For each report we calculated a score per analyte (n = 4), per shipment (n = 24 to 40) and a global score in the 8 shipments (n = 707 to 763 reports). The scores ranged from zero (excellent accuracy) to a maximum of 400 and were calculated by comparison with the modal value of about 600 American and Canadian laboratories which assayed the same controls using exclusively Bayer strips and instrumental readings. RESULTS: The best score was for nitrites (global score of 3 in 741 reports) and the worst for specific gravity (58 in 744 reports); the other analytes had scores from 11 to 19 (Table 1). The scores of four types of methods (Table 2) showed the best results with Bayer strips and instrumental readings (score of 13 in 469 reports) and the worst with strips of other suppliers (scores of 28 for visual and 31 for instrumental readings) and intermediate with visual readings of Bayer strips (score of 21). CONCLUSIONS: 1. Our results led us to the decision to exclude from the program participants who do not use Bayer strips as our program may disorient them instead of helping to improve their assays. 2. We confirmed that instrumental readings perform better than visual readings. 3. The causes of suboptimal performance in specific gravity need to be explored.

Humans↗