Retrospective assessment of asbestos exposure--I. Case-control analysis in a study of lung cancer: efficiency of job-specific questionnaires and job exposure matrices

Our plain-English summary of Retrospective assessment of asbestos exposure--I. Case-control analysis in a study of lung cancer: efficiency of job-specific questionnaires and job exposure matrices, by W. Ahrens, K.H. Jöckel, P. Brochard, et al (International Journal of Epidemiology, 1993).

The study

• Authors: W. Ahrens, K.H. Jöckel, P. Brochard, U. Bolm-Audorff, K. Grossgarten, Y. Iwatsubo, E. Orlowski, H. Pohlabeln, F. Berrino
• Journal: International Journal of Epidemiology
• Published: 1993;22 Suppl 2:S83-95
• Cited by: 53 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Retrospective assessment of asbestos exposure--I. Case-control analysis in a study of lung cancer: efficiency of job-specific questionnaires and job exposure matrices. International Journal of Epidemiology 1993; 22 (Suppl. 2): S83-S95. In a lung cancer study in Northern Germany the asbestos exposure assessment obtained from detailed supplementary questionnaires (SQ) was compared to the assessment obtained by the application of two job exposure matrices (JEM) to the job history. The study includes 391 incident male cases and the same number of controls from the general population, matched by sex, age, and region. Almost 16% of the subjects are considered as never having been exposed to asbestos and 24% are classified as certainly exposed according to both of the JEM, the corresponding percentages of the SQ-method being 68% and 32%. Sixty percent are considered by the JEM as having an intermediate probability of exposure. In general, the agreement between the different methods is better when the exposure definition is restricted to definite exposures, the corresponding Kappa statistic being 0.67 for the comparison between both JEM and 0.44/0.39 between the JEM and the SQ. The positive agreement between SQ and JEM (reference) increases from 12% and 17% for subjects with low probability of exposure to 61% and 69% for those with definite exposures. A ranking according to cumulative exposure shows some dose-response relationship for each of the three methods with a smoking-adjusted OR in the highest category of 1.85 (95% CI: 1.01-3.38) for the SQ method and 2.47 (95% CI: 1.40-4.37) and 2.94 (95% CI: 1.73-4.99) for the two JEM. The results are discussed with reference to the conceptual differences between the methods and their potential scope in future studies.

In plain English

This case-control study of lung cancer in Northern Germany compared ways of estimating past asbestos exposure. It included 391 newly diagnosed male lung cancer cases, recruited from October 1988 to February 1991 mostly in Bremen, and 391 population controls matched by region and age. Exposure up to 1975 was estimated by detailed job-specific questionnaires and by two job exposure matrices (JEMs) built for earlier studies in France and southern Europe. The JEMs classified almost 16% of subjects as never exposed; the questionnaires classified 68%. For definite exposure, the two JEMs agreed better with each other (Kappa 0.67) than with the questionnaires (0.44 and 0.39). After adjusting for smoking, the highest cumulative exposure group had odds ratios of 1.85 (95% CI 1.01-3.38) by questionnaire, and 2.47 (1.40-4.37) and 2.94 (1.73-4.99) by the two JEMs. For questionnaire-assessed exposure up to 1400 lifetime hours, the smoking-adjusted odds ratios (1.06 and 1.12) were not statistically significant. The authors concluded that all three methods showed a significant association compatible with a dose-response relationship. They noted that other exposures, such as welding or diesel fumes, might partly explain the odds ratios.

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: Population-based case-control study of lung cancer with 1:1 matching, used to compare three methods of retrospective asbestos exposure assessment. Analysis was by conditional logistic regression adjusted for smoking, with significance tested one-sided at the 5% level.
• Who was studied: 391 newly diagnosed men with histologically or cytologically confirmed primary lung cancer, born after 1912. Of these, 348 were recruited in Bremen and the rest at two clinics in Frankfurt/Main, between October 1988 and February 1991; mean age 61.0 years. There were 391 controls drawn at random from municipal residence records (response rate 77.7%), individually matched 1:1 by region and age (within 5 years); mean age 61.2 years.
• Exposure: Occupational asbestos exposure up to 1975, with no fiber types specified. It was assessed in three ways: (1) 19 job-specific supplementary questionnaires (SQ) asking about products, handling, calendar time, frequency and hours per day, summarized as lifetime hours of exposure; (2) a JEM built for a mesothelioma study in France (MESO-JEM); (3) a JEM built for a southern European larynx and hypopharynx cancer study (LHC-JEM). The JEMs were applied to coded job titles and industries. The region had past exposure at an asbestos cement manufacturer, shipyards including naval dockyards, and a harbour where raw asbestos was shipped.
• Main results:
  • Each JEM classified almost 16% of all subjects as never exposed and 24% as certainly exposed. The SQ method classified 68% as never exposed and 32% as definitely exposed.
  • For definite exposure, the Kappa statistic was 0.67 between the two JEMs, and 0.44 (MESO-JEM) and 0.39 (LHC-JEM) between each JEM and the SQ.
  • Positive agreement of the SQ with the JEMs (as reference) rose from 12% and 17% for subjects with low probability of exposure to 61% and 69% for those with definite exposure.
  • MESO-JEM, definite exposure (109 cases, 78 controls) versus never exposed: smoking-adjusted OR 2.67 (95% CI 1.54-4.62).
  • In the highest cumulative exposure category, the smoking-adjusted OR was 1.85 (95% CI 1.01-3.38) for the SQ method (more than 5580 lifetime hours). It was 2.47 (95% CI 1.40-4.37) for the MESO-JEM and 2.94 (95% CI 1.73-4.99) for the LHC-JEM (highest quartiles).
  • SQ method, lowest lifetime-hours category (up to 282 hours; 32 cases, 30 controls): smoking-adjusted OR 1.06 (95% CI 0.59-1.92), not statistically significant.
  • SQ method, 282 to 1400 lifetime hours (25 cases, 37 controls): smoking-adjusted OR 1.12 (95% CI 0.60-2.07), not statistically significant. The authors wrote that no excess risk was observed for exposure of up to 1400 lifetime hours.
  • LHC-JEM: the highest OR was in category 33 (occupations with more than two-thirds of workers exposed), with 31 cases and 10 controls and a smoking-adjusted OR of 5.88 (95% CI 2.45-14.16). The authors noted the confidence interval was broad because of small numbers.
  • When asked a direct question about exposure, 16% of controls and 17% of cases reported asbestos exposure. The SQ method classified 29% of controls and 34% of cases as exposed.
  • Combining the two methods, subjects definitely exposed by both the MESO-JEM and the SQ in the highest quarter of lifetime hours (31 cases, 17 controls) had a smoking-adjusted OR of 3.92 (95% CI 1.70-9.07), compared with subjects not exposed by both methods.
• The authors' conclusion: The authors concluded that all three methods showed a significant association between lung cancer and asbestos exposure, with odds ratio patterns compatible with a dose-response relationship. In their view, the two JEMs agreed well with each other, while agreement between the JEMs and the SQ was weaker because of the methods' different concepts.
• Limitations the authors state:
  • The interview data were not externally validated.
  • The JEM approach has limited specificity: everyone in a given job and industry gets the same exposure category, so some non-exposed workers are classified as exposed.
  • The JEMs were built mainly for exposure patterns in France and southern Europe and may not describe exposure in northern Germany adequately.
  • The SQ method may involve some underreporting, and interviewers omitting questionnaires would reduce its sensitivity.
  • Asbestos exposure was strongly associated with exposure to welding or diesel fumes, so the observed odds ratios might partly reflect other exposures.
  • The dual assessment approach was not strictly applicable, because the two methods drew on the same questionnaire, so its results need cautious interpretation.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Epidemiology, Cumulative Exposure, Dose-response relationship.

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