title: Proficiency testing for the detection of anti-citrullinated protein antibody in China.
abstract: BACKGROUND
  Anti-citrullinated protein antibodies (ACPAs) are important for the detection of rheumatoid arthritis (RA). There are many laboratories to detect it in their routine work, but their performance is not displayed in China. To examine the performance of ACPA assays from all laboratories, it is necessary to organize a laboratory proficiency test (PT).
  
  
  METHODS
  A panel of 5 samples, including 4 positive and 1 negative, was produced by the National Center for Clinical Laboratories, using serum derived from patients, then distributed to 271 clinical laboratories. Quantitative and qualitative results reported by the participating laboratories were compared.
  
  
  RESULTS
  Overall, 80.97% (200/247) of the laboratories had eligible PT scores. Of the kits used, most ELISA and chemiluminescence kits had a high sensitivity and specificity. Regarding intra-assay discrepancy, the Roche and Abbott kit had a better variable coefficient. The ratios of the quantitative results to the kit-specific cut-off values were similar.
  
  
  CONCLUSIONS
  Performance varied between laboratories. Reagents and methods are the most important factors. Other factors may affect the intra-assay discrepancy. The similar mean of ratios of the quantitative results to the kit-assigned cut-offs suggests that a national criterion is requisite. It is necessary to organize a PT to identify performances of different laboratories.
authors.affiliation: Graduate School, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, People's Republic of China; National Center for Clinical Laboratories, Peking University of Fifth School Clinical Medicine, Beijing Hospital of the Ministry of Health, Beijing, People's Republic of China.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Li
authors.affiliation: National Center for Clinical Laboratories, Peking University of Fifth School Clinical Medicine, Beijing Hospital of the Ministry of Health, Beijing, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.affiliation: National Center for Clinical Laboratories, Peking University of Fifth School Clinical Medicine, Beijing Hospital of the Ministry of Health, Beijing, People's Republic of China.
authors.forename: Yanxi
authors.initials: Y
authors.lastname: Han
authors.affiliation: Graduate School, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, People's Republic of China; National Center for Clinical Laboratories, Peking University of Fifth School Clinical Medicine, Beijing Hospital of the Ministry of Health, Beijing, People's Republic of China.
authors.forename: Tian
authors.initials: T
authors.lastname: Lu
authors.affiliation: National Center for Clinical Laboratories, Peking University of Fifth School Clinical Medicine, Beijing Hospital of the Ministry of Health, Beijing, People's Republic of China. Electronic address: jmli63hn@gmail.com.
authors.forename: Jinming
authors.initials: J
authors.lastname: Li
mesh_terms: D000906:Antibodies / Q000097:blood* / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*; D002681:China; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D006801:Humans; D059021:Laboratory Proficiency Testing / Q000592:standards; D008163:Luminescent Measurements / Q000592:standards; D010456:Peptides, Cyclic / Q000276:immunology*; D011786:Quality Control; D012680:Sensitivity and Specificity
chemical_list: D000906:Antibodies; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide
keywords: ACPA; Criterion; Cut-off; PT; RA