Drug Information Journal - March 2009 - (Page 142) 142 MEDICAL INFORMATION Dijkman, Fraser, Treasure, Kapke Number (N) of Observations per Analyte TABLE 1 Analyte Leucocyte count Erythrocyte count Hemoglobin Platelet count Serum calcium Serum creatinine Alanine aminotransferase Alkaline phosphatase N 16,350 3,300 16,360 16,160 9,473 11,280 10,619 10,604 16,350 valid leucocyte counts in the data set. The 20 local laboratories with most results contributed 5,677 valid results, 35% of the total. • Percent: This is the percentage of results that were assessed to be in the same class by both the local laboratory and central laboratory; that is, both laboratories declared the result to be below the reference limit, lie within the reference interval, or be above the reference limit. Table 2 is arranged in descending order of percentage agreement between local and central laboratory reference intervals. Of the 16,350 valid and 31 invalid leucocyte counts in the data set, 15,231 (93.2%) were assessed to be the same with respect to the reference interval (below, within, above) by both laboratories. False negatives and false positives were characterized as in Figure 2: TABLE 2 Assessment of Flagging Discrepancies Between Local Laboratory Reference Intervals Versus Central Laboratory Reference Intervals for Leucocyte Counts Percentage False Positive Lab ID 775 695 485 533 593 486 823 770 630 642 638 788 615 543 480 594 557 514 489 355 Number of Results 182 217 187 275 498 237 184 445 445 199 217 213 452 497 248 293 226 204 264 194 Percentage Agreement 98.4 98.2 97.3 96.7 96.4 96.2 96.2 96.2 95.5 95.5 94.9 94.4 94.0 92.6 91.5 89.4 89.4 88.7 86.0 82.5 Low 2.5 3.3 2.7 1.2 4.2 3.7 0.0 1.5 3.2 3.6 5.0 11.1 1.8 10.3 10.3 0.0 17.8 14.9 0.0 22.7 High 0.0 0.0 0.7 0.6 0.0 1.8 0.9 4.9 3.9 0.0 4.1 0.0 7.8 0.0 4.1 9.5 0.0 0.0 5.8 0.0 Percentage False Negative Low 0.0 0.0 0.0 5.6 0.0 0.0 11.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 15.4 0.0 0.0 31.8 0.0 High 0.0 0.0 0.0 5.6 10.3 0.0 0.0 0.0 0.0 18.2 0.0 0.0 0.0 6.0 0.0 0.0 0.0 11.8 0.0 0.0
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