title: Use of combined Shewhart-CUSUM control charts in internal quality control of enzyme-linked immunosorbent assays for the typing of foot and mouth disease virus antigen.
abstract: An enzyme-linked immunosorbent assay (ELISA) for the typing of foot and mouth disease virus (FMDV) antigen was employed for the routine laboratory diagnosis of FMD at a regional veterinary laboratory in northern Thailand. An objective procedure was developed to monitor the test performance of the ELISA, using absolute test control limits in a Shewhart-CUSUM (cumulative sum) control chart method. The procedure detected significant data trends and 'beyond control limit' situations for each antigen typing system (types O, A and Asia 1), using an assay variable (gamma i). Retrospective analysis using Shewhart-CUSUM control charts of data from 42 ELISAs demonstrated that control limits were exceeded in two assays for FMDV type A. The Shewhart-CUSUM control chart is a simple and reliable internal quality control method for the detection of significant random and systematic variation in assays.
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Australian Animal Health Laboratory, Geelong, Victoria.
authors.forename: S D
authors.initials: SD
authors.lastname: Blacksell
authors.forename: L J
authors.initials: LJ
authors.lastname: Gleeson
authors.forename: R A
authors.initials: RA
authors.lastname: Lunt
authors.forename: C
authors.initials: C
authors.lastname: Chamnanpood
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000032:analysis*; D005537:Aphthovirus / Q000145:classification* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards / Q000662:veterinary*; D016014:Linear Models; D011786:Quality Control; D012703:Serotyping / Q000592:standards / Q000662:veterinary
chemical_list: D000956:Antigens, Viral