In Reply Dr Swartz is concerned because the effect estimates reported in our study were standardized by age group (classified as 50-54 vs 55-64 years) and because previously published articles from the Norwegian Colorectal Cancer Prevention (NORCCAP) trial did not standardize for age.
Previous articles included only the 55- to 64-year age group (or only the screening group) and therefore had no need to consider this issue. Our article is the first to report results for the 50- to 54-year-old age group (including the control group), and therefore we had to consider the different age distribution between the screening and control groups in the analysis.
Holme Ø, Loberg M, Kalager M. Colorectal Cancer and the Effect of Flexible Sigmoidoscopy Screening—Reply. JAMA. 2014;312(22):2411-2412. doi:10.1001/jama.2014.14695