title: Process control procedures to augment quality control of leukocyte-reduced red cell blood products.
abstract: Quality control of leukocyte-reduced packed red cell units (LRprc) produced in blood facilities must conform to regulatory criteria, which state that units may not contain more than 1 x 10(6) to 5 x 10(6) white blood cells (WBC) per unit. The post-filtration WBC content of a total of n = 386 LRprc units was counted with a Nageotte chamber to model the probability that a unit would not meet the regulatory criteria. The distribution of the residual leukocyte counts is close to a negative binomial distribution (NBD) and is independent of the packed red cell volume filtered. The observed probability that a unit of blood has a residual WBC greater than 5 x 10(6) is 2.6 +/- 2.6 x 10(-3). A power analysis of the two-sample Kolmogorov-Smirnov (KS) test in this application shows that a sample size of 20 is sufficient for determining that the process is in control when an out of control process has a k NBD parameter greater than or equal to that of the in control process. The three out of control processes observed to date appear to have this property. A sample of size 80 may be necessary for confirming that process validation data sets conform to the larger 'reference' database (n = 386) for processes that are out of control in such a way that their k NBD parameter is less than the k parameter of the in control process.
authors.affiliation: SUNY Stony Brook, Department of Applied Mathematics and Statistics 11794, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Finch
authors.forename: J B
authors.initials: JB
authors.lastname: Chen
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: M M
authors.initials: MM
authors.lastname: Hall
authors.forename: V
authors.initials: V
authors.lastname: Matkovich
authors.forename: B
authors.initials: B
authors.lastname: Wenz
authors.forename: H
authors.initials: H
authors.lastname: Brandwein
authors.forename: J
authors.initials: J
authors.lastname: Whitbread
mesh_terms: D001781:Blood Component Removal / Q000706:statistics & numerical data*; D017707:Erythrocyte Transfusion / Q000592:standards*; D005374:Filtration; D006801:Humans; D007958:Leukocyte Count; D016013:Likelihood Functions; D015233:Models, Statistical; D011786:Quality Control; D012015:Reference Standards; D014481:United States