... onlyuntil the date of first symptom of RA, rather than until the date of RA diagnosis. We also performed lagged analyses suchthat the dietary intakes associated with RA cases wereassessed at least ... hazardsanalyses to calculate the rate ratio of RA associated with intakes of protein (total, animal, and vegetable) and iron (total, dietary, from supplements, and heme iron) and their primary foodsources, ... irregular) in 1982.Statistical analyses The number of person-years of follow up was ascertainedbased on the interval between the date of return of the 1980questionnaire and the date of diagnosis of...