RE: An alternate characterization of hazard in occupational epidemiology: years of life lost per years worked. Am J Ind Med 42:1–10, 2002

To the Editor: We thank Dr. Morfeld for his interest and appreciate the careful and detailed effort that he has undertaken in analyzing our recent study on work‐related years of potential life lost [Park et al., 2003]. Dr. Morfeld is concerned that our approach, while "attractive in its simplicity," may suffer from several sources of bias. However, upon examination, his specific example appears to us to be inappropriate. A key element in Dr. Morfeld's argument for two of the sources of bias is a hypothetical population in which deaths resulting from an exposure are arbitrarily postulated to have been moved forward in time by 5 years. This stipulation was not derived from empirical evidence or a failure‐time model, and ignores the reference population's survival characteristics as summarized in a relevant life‐table.