title: Women's features and inter-/intra-rater agreement on mammographic density assessment in full-field digital mammograms (DDM-SPAIN).
abstract: Measurement of mammographic density (MD), one of the leading risk factors for breast cancer, still relies on subjective assessment. However, the consistency of MD measurement in full-digital mammograms has yet to be evaluated. We studied inter- and intra-rater agreement with respect to estimation of breast density in full-digital mammograms, and tested whether any of the women's characteristics might have some influence on them. After an initial training period, three experienced radiologists estimated MD using Boyd scale in a left breast cranio-caudal mammogram of 1,431 women, recruited at three Spanish screening centres. A subgroup of 50 randomly selected images was read twice to estimate short-term intra-rater agreement. In addition, a reading of 1,428 of the images, performed 2 years before by one rater, was used to estimate long-term intra-rater agreement. Pair-wise weighted kappas with 95% bootstrap confidence intervals were calculated. Dichotomous variables were defined to identify mammograms in which any rater disagreed with other raters or with his/her own assessment, respectively. The association between disagreement and women's characteristics was tested using multivariate mixed logistic models, including centre as a random-effects term, and taking into account repeated measures when required. All quadratic-weighted kappa values for inter- and intra-rater agreement were excellent (higher than 0.80). None of the studied women's features, i.e. body mass index, brassiere size, menopause, nulliparity, lactation or current hormonal therapy, was associated with higher risk of inter- or intra-rater disagreement. However, raters differed significantly more in images that were classified in the higher-density MD categories, and disagreement in intra-rater assessment was also lower in low-density mammograms. The reliability of MD assessment in full-field digital mammograms is comparable to that for original or digitised images. The reassuring lack of association between subjects' MD-related characteristics and agreement suggests that bias from this source is unlikely.
authors: Cancer and Environmental Epidemiology Unit, National Center for Epidemiology, Instituto de Salud Carlos III, Sinesio Delgado 6, 28029 Madrid, Spain. bperez@isciii.es
authors: Beatriz
authors: B
authors: Pérez-Gómez
authors: Franciso
authors: F
authors: Ruiz
authors: Inmaculada
authors: I
authors: Martínez
authors: María
authors: M
authors: Casals
authors: Josefa
authors: J
authors: Miranda
authors: Carmen
authors: C
authors: Sánchez-Contador
authors: Carmen
authors: C
authors: Vidal
authors: Rafael
authors: R
authors: Llobet
authors: Marina
authors: M
authors: Pollán
authors: Dolores
authors: D
authors: Salas
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D055088:Early Detection of Cancer / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000473:pathology*; D008327:Mammography / Q000379:methods* / Q000592:standards; D008875:Middle Aged; D015588:Observer Variation; D012307:Risk Factors; D013030:Spain