Detecting failed WBC-reduction processes: computer simulations of intermittent and continuous process failure.
Background: By regulation, ongoing process control of WBC-reduced processes is performed on 1 percent of WBC-reduced components, typically four to five samples per month. However, prospective study of the power of this small sample has been difficult. Using computer-generated "residual WBC" distribu...
| Publicado en: | Transfusion Vol. 40; no. 12; pp. 1427 - 1434 |
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| Autores principales: | , , , , , , , , , |
| Formato: | CEU research tables/charts Journal Article |
| Publicado: |
Wiley-Blackwell
Dec2000
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=107015356&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 107015356 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 00411132 1YB jtl: Transfusion issn: 00411132 maglogo: Y pubinfo: dt: Dec2000 vid: 40 iid: 12 pid: 480 pub: Wiley-Blackwell place: Malden, Massachusetts artinfo: ui: 107015356 107015356 NLM11134560 2001033534 NLM11134560 107015356 ppf: 1427 ppct: 7 formats: tig: atl: Detecting failed WBC-reduction processes: computer simulations of intermittent and continuous process failure. aug: au: Adams MR Fisher DM Dumont LJ Dzik WH Heaton WA Adams, M R Fisher, D M Dumont, L J Dzik, W H Heaton, W A affil: Department of Medicine, University of California, San Francisco, CA 94143-0532, USA sug: subj: Blood Component Removal Leukocytes Quality Assurance Quality Control (Technology) Computer Simulation Confidence Intervals Education, Continuing (Credit) Human ab: Background: By regulation, ongoing process control of WBC-reduced processes is performed on 1 percent of WBC-reduced components, typically four to five samples per month. However, prospective study of the power of this small sample has been difficult. Using computer-generated "residual WBC" distributions, sample size sensitivity to continuous or intermittent WBC-reduction failure was examined.Study Design and Methods: Populations of log-normally distributed values (mean +/- SD, 4.5+/-0.5; n = 10(5)) were generated. Continuous failure (log-normality maintained) was simulated by incrementally increasing the population mean or its SD. Intermittent failure (bimodal distributions with discrete subpopulations of WBCs > the FDA cutoff) was simulated by admixing increasing percentages of secondary outlier populations. Sample sizes of 4 to 60 were examined (500 repetitions each) for their power to detect drift or failure by standard control criteria.Results: Normally distributed low variance failure was easily detected by comparison of the mean of four samples to an upper control limit (95% confidence of detecting 2% failure). However, 40 samples were required to detect > 5 percent intermittent (bimodal) failure or high variance failure with 90-percent confidence, and only if individual WBC values were compared to cutoff.Conclusion: Sampling error limits the detection of high variance or bimodal distributions. While the mean of a small sample is highly sensitive to shifts in a low-variance normal distribution, the detection of a high-variance bimodal population requires a large number of individual values compared to cutoff. Therefore, the number of samples required for confident failure detection depends on both the nature of the underlying distribution and the interpretive criteria. Further research is necessary to determine the true distributions of WBC-reduction process failure, as well as clinically relevant quality limits. pubtype: Academic Journal doctype: CEU research tables/charts Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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