Invited Commentary: Missing doses in the Life Span Study of Japanese atomic bomb survivors

Ozasa K, Grant EJ, Cullings HM, Shore RE
Am J Epidemiol 2013 (March); 177(6):569-73
doi: 10.1093/aje/kws474

Abstract

The Life Span Study is a long-term epidemiologic cohort study of survivors of the atomic bombs dropped on Hiroshima and Nagasaki, Japan. In this issue of the Journal, Richardson et al. (Am J Epidemiol. 2013;177(6):562-568) suggest that those who died in the earliest years of follow-up were more likely to have a missing dose of radiation exposure assigned, leading to a bias in the radiation risk estimates. We show that nearly all members of the cohort had shielding information recorded before the beginning of follow-up and that much of the alleged bias that Richardson et al. describe simply reflects the geographic distribution of shielding conditions for which reliable dosimetry was impossible.