To asses inter- and intra-observer variability for breast density and BIRADS assessment categories in mammographic reporting

Objective: To evaluate the inter- and intra-observer variability among radiologists in the characterisation of mammograms according to Breast Imaging Reporting and Data System assessment and breast density categories. Methods: The descriptive cross-sectional study was conducted at Aga Khan University Hospital, Karachi, from January 2014 to June 2014. Using non-probability purposive sampling, all mammograms in the study were interpreted by three radiologists on the basis of Breast Imaging Reporting and Data System categories and by assessing the breast density composition. The inter-observer variability was recorded by comparing the difference in the interpretation and categorisation of each case. Intra-observer variability was noted by comparing the differences in the two sets of results from reading the same mammogram three months apart. Results: A total of 254 mammograms were reviewed and the mean age of patients was 55.2±11.6 years. In the first round of diagnostic imaging, there was moderate agreement among all three possible pairs of observers regarding breast density (k= 0.50-0.41), but for Breast Imaging Reporting and Data System categories the agreement was less (k=0.27-0.13). After 3 months, variability of observer 1 showed substantial agreement (k=0.65).Variability between observer 2 and observer 3 showed moderate agreement (k=0.13).In terms of categories, intra-observer differences were variable: observer 1 (?=0.61; observer 2(?=0.17); observer 3 (k=0.45). Conclusion: Despite standardised guidelines for reporting density and assessment categories, observer variability continues to exist.