Experiences with Observer Variation in Mesothelioma Panels

Our plain-English summary of Experiences with Observer Variation in Mesothelioma Panels, by H.T. Planteydt (1980).

The study

• Author: H.T. Planteydt
• Published: BIOLOGICAL EFFECTS OF MINERAL FIBRES (J.C. WAGNER, EDITOR), LYON: IARC SCIENTIFIC PUBLICATIONS, VOLUME 30., PP 211-216 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This article described one pathologist's experience of how often pathologists on diagnostic panels agreed when judging whether tumour slides showed malignant mesothelioma. The author did not study asbestos exposure. The Dutch Mesothelioma Panel, the European Communities (CEC) panel and the IARC panel for the United Kingdom graded each case on a five-step scale, from A (definite malignant mesothelioma) to E (not a malignant mesothelioma). The CEC panel later added a sixth category, F, for unsatisfactory material. In the Dutch panel, three pathologists rated 67 consecutive cases. All had been diagnosed as mesothelioma by the original pathologist. At first, the three agreed completely on 13 cases and disagreed widely on 18. The most divergent pathologist then re-examined those 18 cases. Afterwards, gross disagreement remained in 4 of the 67 cases. Doubtful cases had nearly all been diagnosed from needle biopsies rather than larger pieces of tissue. Examples from the other two panels showed agreement often improved after discussion or a second viewing. The author concluded that the voting system usually led to good or reasonable agreement, but that disagreement "lessened but did not disappear."

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Descriptive report of the author's experience with a voting system for grading diagnoses in three mesothelioma pathology panels (observer variation study), using five categories, A to E
• Who was studied: Dutch Mesothelioma Panel: 67 consecutive cases diagnosed as mesothelioma by the original pathologist, from the Rotterdam area and the north-eastern Netherlands, plus a further 30 cases sent for opinion. The CEC panel saw a selection of 62 cases and the IARC UK panel a selection of 40 cases.
• Exposure: Not studied. The article is about agreement among pathologists, not about asbestos exposure. The 67 Dutch cases had previously been used in a study of occupational histories by Zielhuis et al. (1975).
• Main results:
  • The CEC panel later added a sixth category, F, for unsatisfactory material with no valid evidence for a diagnosis
  • Dutch panel, 67 cases, first rating: complete agreement in 13 cases, nearly complete agreement in 31, reasonable agreement in 6, and major disagreement in 18
  • Dutch panel, 67 cases, after the most divergent pathologist re-examined the 18 disputed cases: complete agreement in 16, nearly complete agreement in 40, reasonable agreement in 7, and disagreement in 4
  • Final Dutch panel conclusions for the 67 cases: 44 positive, 9 dubious, 10 negative and 4 gross disagreement
  • Nearly all dubious cases had been diagnosed from a needle biopsy. Of 18 Abrams' needle biopsy cases, 10 were positive, 7 dubious and 1 in gross disagreement.
  • The four cases of gross disagreement came from both autopsy and biopsy material
  • In one case (MR 230/259), the Dutch panel rated biopsy material as dubious, but all pathologists rated the autopsy material as definite mesothelioma
• The authors' conclusion: The author concluded that the voting system made it easier to measure and compare diagnostic opinions and usually led to good or reasonable agreement among panel members. Agreement was usually greater on a second viewing, and disagreement lessened with experience but did not disappear.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos Exposure, IARC.

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