{
  "abstract": "Objectives Traditional epidemiological approaches usually assume a constant relationship between cumulative exposure and disease, which implies that exposure duration and intensity contribute equally to the studied outcome. But individuals with the same cumulative exposure but different temporal exposure patterns may show different risks. Trajectory classification is a good way to assess exposure–risk associations and leads to a better understanding of lifetime variability in exposure levels. Therefore, this study aimed to estimate lung cancer risk according to the exposure trajectory classes on welding fumes and cigarette smoking.Design Two population-based German case–control studies.Participants 3498 male lung cancer cases and 3539 male control subjects.Methods Separate latent class mixed models (LCMM) were determined to identify profiles of exposure trajectories of cigarette smoking and occupational exposure to welding fumes. To investigate the risk of lung cancer by class membership, ORs with 95% CI were estimated via multiple logistic regression analyses.Results LCMM each identified four latent classes of smoking and welding-fume exposure. Classes of smokers showed much higher risk of lung cancer compared with never smokers or subjects exposed to welding fumes. Smokers in one class characterised with the highest exposure over the past 10 years had the highest adjusted lung cancer risk (OR=39; 95% CI 29 to 53). For welding, the highest lung cancer risks were found for the class in which exposure to welding fumes in the past 10 years prior to the diagnosis of lung cancer was highest and the duration of welding was also quite high (OR=1.71; 95% CI 0.92 to 3.15).Conclusions In summary, LCMM opens a new perspective on dose–effect relationships and could be employed to complement established epidemiological methods.",
  "authors": [
    {
      "affiliations": [
        "Institute of the Ruhr-Universität Bochum, Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (IPA), Bochum, Germany"
      ],
      "name": "Benjamin Kendzia"
    },
    {
      "affiliations": [
        "Institute of the Ruhr-Universität Bochum, Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (IPA), Bochum, Germany"
      ],
      "name": "Dirk Taeger"
    },
    {
      "affiliations": [
        "Epidemiological Methods and Etiological Research, Leibniz-Institute for Prevention Research and Epidemiology-BIPS GmbH and Institute for Statistics, University of Bremen, Bremen, Germany"
      ],
      "name": "Hermann Pohlabeln"
    },
    {
      "affiliations": [
        "Epidemiological Methods and Etiological Research, Leibniz-Institute for Prevention Research and Epidemiology-BIPS GmbH and Institute for Statistics, University of Bremen, Bremen, Germany"
      ],
      "name": "Wolfgang Ahrens"
    },
    {
      "affiliations": [
        "Institute of Epidemiology I, Helmholtz Centre Munich, Neuherberg, Germany"
      ],
      "name": "Heinz-Erich Wichmann"
    },
    {
      "affiliations": [
        "Institute for Medical Informatics, Biometry and Epidemiology, University Hospital Essen, Essen, Germany"
      ],
      "name": "Karl-Heinz Jöckel"
    },
    {
      "affiliations": [
        "Institute of the Ruhr-Universität Bochum, Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (IPA), Bochum, Germany"
      ],
      "name": "Thomas Brüning"
    },
    {
      "affiliations": [
        "Institute of the Ruhr-Universität Bochum, Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (IPA), Bochum, Germany"
      ],
      "name": "Thomas Behrens"
    }
  ],
  "title": "Trajectories of cigarette smoking and exposure to welding fumes and their impact on lung cancer risks: a latent class modelling approach",
  "uid": "c1173891-fb80-53ca-94d7-7c841a4539b5"
}