Using administrative data to estimate time to breast cancer diagnosis and percent of screen-detected breast cancers – a validation study in Alberta, Canada.

Appropriate use of administrative data enables the assessment of care quality at the population level. Our objective was to develop/validate methods for assessing quality of breast cancer diagnostic care using administrative data, specifically by identifying relevant medical tests to estimate the percentage screen/symptom-detected cancers and time to diagnosis. Two databases were created for all women diagnosed with a first-ever breast cancer in years 2007-2010 in Alberta, Canada, with dates of medical tests received in years 2006-2010. One purchased database had test results and was used to determine the 'true' first relevant test of a cancer diagnosis. The other free administrative database had test types but no test results. Receiver operating characteristic curves and concordance rates were used to assess estimates of percent screen/symptom-detected breast cancers; Log-rank test was used to assess time to diagnosis obtained from the two databases. Using a look-back period of 4-6 months from cancer diagnosis to identify relevant tests resulted in over 94% concordance, sensitivity and specificity for classifying patients into screen/symptom-detected group; good agreement between the distributions of time to diagnosis was also achieved. Our findings support the use of administrative data to accurately identify relevant tests for assessing the quality of breast cancer diagnostic care.