title: Breast Cancer and Modifiable Lifestyle Factors in Argentinean Women: Addressing Missing Data in a Case-Control Study
abstract: A number of studies have evidenced the effect of modifiable lifestyle factors such as diet, breastfeeding and nutritional
  status on breast cancer risk. However, none have addressed the missing data problem in nutritional epidemiologic research
  in South America. Missing data is a frequent problem in breast cancer studies and epidemiological settings in general.
  Estimates of effect obtained from these studies may be biased, if no appropriate method for handling missing data is
  applied. We performed Multiple Imputation for missing values on covariates in a breast cancer case-control study of
  Córdoba (Argentina) to optimize risk estimates. Data was obtained from a breast cancer case control study from 2008
  to 2015 (318 cases, 526 controls). Complete case analysis and multiple imputation using chained equations were the
  methods applied to estimate the effects of a Traditional dietary pattern and other recognized factors associated with
  breast cancer. Physical activity and socioeconomic status were imputed. Logistic regression models were performed.
  When complete case analysis was performed only 31% of women were considered. Although a positive association
  of Traditional dietary pattern and breast cancer was observed from both approaches (complete case analysis OR=1.3,
  95%CI=1.0-1.7; multiple imputation OR=1.4, 95%CI=1.2-1.7), effects of other covariates, like BMI and breastfeeding,
  were only identified when multiple imputation was considered. A Traditional dietary pattern, BMI and breastfeeding are
  associated with the occurrence of breast cancer in this Argentinean population when multiple imputation is appropriately
  performed. Multiple Imputation is suggested in Latin America’s epidemiologic studies to optimize effect estimates in
  the future.
authors.affiliation: Instituto de Investigaciones en Ciencias de la Salud (INICSA-UNC-CONICET), Universidad Nacional de Cordoba (UNC), Cordoba Capital, Cordoba, Argentina. Email: pdiaz@fcm.unc.edu.ar
authors.forename: Julia
authors.initials: J
authors.lastname: Becaria Coquet
authors.forename: Natalia
authors.initials: N
authors.lastname: Tumas
authors.forename: Alberto Ruben
authors.initials: AR
authors.lastname: Osella
authors.forename: Matteo
authors.initials: M
authors.lastname: Tanzi
authors.forename: Isabella
authors.initials: I
authors.lastname: Franco
authors.forename: Maria Del Pilar
authors.initials: Mdel P
authors.lastname: Diaz
keywords: Body mass index; breastfeeding; cancer epidemiology; dietary pattern; multiple imputation