Inter-rater agreement of sputum cytology for lung cancer screening in Japan

Chiaki Endo, Ryutaro Nakashima, Akemi Taguchi, Kazunobu Yahata, Ei Kawahara, Nikako Shimagaki, Junko Kamio, Yasuki Saito, Norihiko Ikeda, Masami Sato

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Background To compare lung cancer detection rate by sputum cytology, we need some assurance that the estimates do not vary widely if different observers evaluate the same specimens. The aim of this study was to determine inter-rater agreement of sputum cytology diagnoses. Methods Slides of sputum cytology from 150 subjects were selected from a pool of slides held by six of the laboratories that had participated in a population-based lung cancer screening program over the last ten years in Japan. The cytotechnologists in these laboratories had considerable experience with sputum cytology. Each case was re-evaluated six times. Cases that were diagnosed as the same category by all six laboratories were selected as consensus cases to serve as standardized sputum cytology cases. Thirty-seven cytotechnologists with various levels of experience in sputum cytology then re-evaluated these consensus cases. Inter-rater agreement was calculated by kappa statistics including Fleiss' kappa. Results All pairs of interlaboratory agreement for the 150 cases showed statistically significant kappa values, most pairs showing substantial agreement. Fleiss' kappa value across the six laboratories was 0.5. Fourteen cases were identified as the consensus cases, and the agreement among observers with less experience of sputum cytology showed significantly lower than the agreement among those with considerable experience (Fleiss' kappa value 0.27 vs. 0.45, P?<?0.05). Moreover, cytotechnologists with less experience under-diagnosed the slides significantly more often than those with considerable experience. Conclusion When the observers have considerable experience with sputum cytology, inter-observer agreement is good. Diagn. Cytopathol. 2015;43:545-550.

Original languageEnglish
Pages (from-to)545-550
Number of pages6
JournalDiagnostic Cytopathology
Issue number7
Publication statusPublished - 2015 Jul 1


  • Fleiss'
  • interrater agreement
  • kappa
  • kappa statistics
  • lung cancer screening
  • quality assurance
  • sputum cytology

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology


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