Confounding from smoking in occupational epidemiology.

Confounding from smoking in occupational epidemiology.

Practice of Epidemiology Time-modified Confounding

According to the authors, time-modified confounding occurs when the causal relation between a time-fixed or time-varying confounder and the treatment or outcome changes over time. A key difference between previously described time-varying confounding and the proposed time-modified confounding is that, in the former, the values of the confounding variable change over time while, in the latter, t...

Intervention studies in occupational epidemiology.

Correspondence to: Prof. T S Kristensen, National Institute of Occupational Health, Lerso Parkalle 105, DK-2100 Copenhagen O, Denmark; [email protected] _________________________ T he proportion of intervention studies in occupational epidemiology has been growing rapidly in recent years. This is a positive trend, which makes it necessary to discuss a number of theoretical, methodological, and practic...

Bias in occupational epidemiology studies.

The design of occupational epidemiology studies should be based on the need to minimise random and systematic error. The latter is the focus of this paper, and includes selection bias, information bias and confounding. Selection bias can be minimised by obtaining a high response rate (and by appropriate selection of the control group in a case-control study). In general, it is important to ensu...

Practice of Epidemiology Environmental Confounding in Gene-Environment Interaction Studies

We show that, in the presence of uncontrolled environmental confounding, joint tests for the presence of a main genetic effect and gene-environment interaction will be biased if the genetic and environmental factors are correlated, even if there is no effect of either the genetic factor or the environmental factor on the disease. When environmental confounding is ignored, such tests will in fac...