Competing interests
All authors declare that they have no known competing financial interests. As staff of the Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University (IPA), the authors are employed by the study’s main financing body, the German Social Accident Insurance. IPA is an independent research institute of the Ruhr-University Bochum. The authors are independent from the German Social Accident Insurance in study design, access to the collected data, responsibility for data analysis and interpretation, and the right to publish.