title: [Oral contraceptives and breast cancer: analysis of the statistical power of the association].
abstract: The power of the association between oral contraceptives and breast cancer was analysed in all the papers published up to date. Seventy-seven publications (from 44 studies) were collected and graded as to quality using meta-analytical methods. Power achieved a figure of greater than or equal to 0.8 in a 10.8% of the associations studied. It showed a significant relationship with the existence of a significant relative risk of the oral contraceptives for breast cancer. The relationship with the sample size of a study was not linear. Power did not show any significant relationship to other variables related to the design of a study (apart from matching, being the power higher in unmatched studies), or to the biases detected, although studies considered as unbiased yielded a higher power. Logistic regression analysis included as predictors of a power greater than or equal to 0.80 the existence of a significant relative risk and the lack of biases in a research.
authors.affiliation: Departamento de Medicina Preventiva, Facultad de Medicina, Granada.
authors.forename: M
authors.initials: M
authors.lastname: Delgado Rodríguez
authors.forename: M
authors.initials: M
authors.lastname: Sillero Arenas
authors.forename: R
authors.initials: R
authors.lastname: Rodríguez-Contreras
authors.forename: A
authors.initials: A
authors.lastname: Bueno Cavanillas
authors.forename: J M
authors.initials: JM
authors.lastname: Martín Moreno
authors.forename: R
authors.initials: R
authors.lastname: Gálvez Vargas
mesh_terms: D000704:Analysis of Variance; D015982:Bias; D001943:Breast Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008593:Menopause; D015201:Meta-Analysis as Topic; D012044:Regression Analysis; D012306:Risk
chemical_list: D003276:Contraceptives, Oral
vernacular_title: Anticonceptivos orales y cáncer de mama: análisis de la potencia estadística de la asociación.