title: Breast bud detection: a validation study in the Chilean growth obesity cohort study.
abstract: BACKGROUND
  Early puberty onset has been related to future chronic disease; however breast bud assessment in large scale population studies is difficult because it requires trained personnel. Thus our aim is to assess the validity of self and maternal breast bud detection, considering girl's body mass index (BMI) and maternal education.
  
  
  METHODS
  In 2010, 481 girls (mean age = 7.8) from the Growth and Obesity Chilean Cohort Study were evaluated by a nutritionist trained in breast bud detection. In addition, the girl(n = 481) and her mother(n = 341) classified the girl's breast development after viewing photographs of Tanner stages. Concordance between diagnostics was estimated (kappa, Spearman correlation) considering girls' BMI and mother's educational level.
  
  
  RESULTS
  14% of the girls presented breast buds and 43% had excess weight (BMI z-score > 1, World Health Organization 2007). Self-assessment showed low concordance with the evaluator (K < 0.1) and girls with excess weight over-diagnosed more than girls of normal weight (44% vs. 24%, p-value < 0.05). Instead, mothers showed good concordance with the evaluator (K = 0.7, 95% confidence interval (CI) = 0.6-0.9), even in overweight girls and/or in mothers with low education (K = 0.7, 95% CI = 0.6-0.8).
  
  
  CONCLUSIONS
  Mothers were able to adequately evaluate the appearance of breast bud despite low educational level and girls' excess weight. Mother could be a useful resource for defining puberty onset in epidemiological studies, particularly developing countries.
authors.forename: Ana
authors.initials: A
authors.lastname: Pereira
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Garmendia
authors.forename: Daniela
authors.initials: D
authors.lastname: González
authors.forename: Juliana
authors.initials: J
authors.lastname: Kain
authors.forename: Verónica
authors.initials: V
authors.lastname: Mericq
authors.forename: Ricardo
authors.initials: R
authors.lastname: Uauy
authors.affiliation: Institute of Nutrition and Food Technology, University of Chile, Avda, El Líbano 5524, Macul, Santiago, Chile. ccorvalan@inta.uchile.cl.
authors.forename: Camila
authors.initials: C
authors.lastname: Corvalán
mesh_terms: D015992:Body Mass Index; D001940:Breast / Q000254:growth & development*; D002648:Child; D002677:Chile; D015331:Cohort Studies; D059026:Diagnostic Self Evaluation; D004522:Educational Status; D005260:Female; D006801:Humans; D009035:Mothers; D009765:Obesity; D050177:Overweight; D011627:Puberty / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology*