Evaluation of the quality of coding of job episodes collected by self questionnaires among French retired men for use in a job-exposure matrix

Our plain-English summary of Evaluation of the quality of coding of job episodes collected by self questionnaires among French retired men for use in a job-exposure matrix, by C. Pilorget, E. Imbernon, M. Goldberg, et al (Occupational and Environmental Medicine, 2003).

The study

• Authors: C. Pilorget, E. Imbernon, M. Goldberg, S. Bonenfant, Y. Spyckerelle, B. Fournier, J. Steinmetz, A. Schmaus
• Journal: Occupational and Environmental Medicine
• Published: 2003;60(6):438-43
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: and

Aims: The ESPACES study was intended to identify retirees who may have been, according to their job descriptions, exposed to asbestos during their working lives. As part of this study, we analysed the quality of the occupation and activity sector coding as well as its effect on the subjects' exposure status.

Methods: The occupation and activity sector for a sample of 450 retired men were coded twice (with the second coder blinded to the first result), according to the international codes for industries (ISIC-1975) and occupations (ISCO-1968). For each series, linking the information about a job episode (dates, ISIC code, ISCO code) with the matrix allowed attribution of a probability of asbestos exposure to each episode and each subject. The asbestos exposure in the two series was compared by the kappa reproducibility coefficient.

Results: The analysis concerned 425 questionnaires. There was at least one difference in the code for either activity sector (ISIC) or occupation (ISCO) in half the episodes (50.2%). The exposure status estimated by the job-exposure matrix did not change between the series for 84.7% of the subjects. The kappa coefficient was 0.64 for all questionnaires, 0.70 when the questionnaire was coded twice by the same coder, and 0.62 when coded by two different coders.

Conclusions: Despite intra- and inter-differences between coders, the coding of job episodes for the ESPACES study appears satisfactory and hence indicates that the assessment of the subjects' asbestos exposure was assessed without major distortions. This study underlines the usefulness of employing coders specifically trained for this technique.

In plain English

This study checked how consistently job histories were coded in the French ESPACES project. That project aimed to identify retired men who may have been exposed to asbestos at work. Retired men had described their jobs in mailed questionnaires. Staff translated each job into international occupation and industry codes, which were then linked to a job-exposure matrix, a table that assigns a probability of asbestos exposure to each job. A random sample of 450 questionnaires was coded twice, either by the same coder or by a different one. In all, 425 subjects with 2099 job episodes were analysed. At least one code differed between the two codings in 50.2% of episodes, yet 84.7% of subjects kept the same exposure status. Agreement (kappa) for subject exposure status was 0.64 overall, 0.70 for the same coder and 0.62 for different coders. The authors concluded that coding was satisfactory and exposures were assessed without major distortions, and they recommended specialist coders. They noted that the coders were doing such coding for the first time and that the international codes were less precise than French national codes.

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: Methodological reliability study: a random sample of questionnaires was coded twice (blinded second coding) and the resulting job-exposure matrix asbestos classifications were compared using kappa coefficients
• Who was studied: Recently retired men (retired in 1994, 1995 and 1996) randomly selected in 1998 from National Health Insurance files in six French départements. From their questionnaires, 450 were sampled for double coding and 425 subjects with 2099 job episodes were analysed.
• Exposure: Occupational asbestos exposure (no fiber types named), estimated by an asbestos-specific job-exposure matrix. The matrix assigned each occupation/industry code combination a probability of exposure: non-exposed, 0.05, 0.3, 0.5, 0.7 or 1.
• Main results:
  • The final analysis included 425 subjects with 2099 job episodes.
  • 1054 of the job episodes (50.2%), belonging to 354 subjects (83.2%), had at least one difference in the industry (ISIC) or occupation (ISCO) code between the two coding series.
  • Most episodes (81.7%) and subjects (84.7%) had the same exposure status in both coding series.
  • A change from exposed to unexposed, or the reverse, occurred in 4.5% of subjects.
  • Kappa was 0.69 for episode exposure status. For subjects, kappa was 0.64 for exposure status and 0.60 for exposure probability.
  • For questionnaires coded twice by the same coder, kappa for subject exposure status was 0.70. For questionnaires coded by two different coders, it was 0.62.
  • Among individual coders coding the same questionnaires twice, kappa for subject exposure status ranged from 0.86 (coder 1) to 0.53 (coder 2).
  • Among subjects who attended a physician interview, 29.5% of those classified as exposed by the matrix were judged non-exposed by the physician (n = 31) in the first coding, and 31.8% (n = 35) in the second.
  • Of subjects who said they had not been exposed to asbestos, 65% (first coding) and 70% (second coding) were classified as possibly exposed by the matrix.
• The authors' conclusion: The authors concluded that, despite differences within and between coders, the coding was satisfactory and the subjects' asbestos exposures were assessed without major distortions. They recommended using specialist coders in general-population studies that use a job-exposure matrix.
• Limitations the authors state:
  • All three coders were doing this kind of coding for the first time, although they had been specifically trained.
  • Missing codes were twice as frequent for activity sectors (6%) as for occupations (3%).
  • The code for unspecified labourers was used fairly often (8.3% and 8% in the two series), often when information was insufficient.
  • French national codes would have been better adapted and more precise, but they were not compatible with the matrix, which was built on international classifications.
  • Only 124 of the 303 eligible persons came for the physician interview.

Topics

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

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