With increasing availability of massive quantities of health care data and advances in technology for data analyses, novel investigations of health delivery and outcomes are proliferating. In this issue of JAMA Internal Medicine, Harding et al1 investigate the health effects of screening mammography through the merging of 2 large data sources using an ecological study design. The study correlates US county-level estimates of mammography, based on national surveys of women who recount prior mammography examinations, with breast cancer incidence and mortality rates from the Surveillance, Epidemiology, and End Results registry. Harding et al report increased rates of breast cancer diagnoses in areas where more women have undergone screening mammography examinations, but no apparent correlation between increased mammography and subsequent breast cancer mortality.
Elmore JG, Etzioni R. Effect of Screening Mammography on Cancer Incidence and Mortality. JAMA Intern Med. 2015;175(9):1490-1491. doi:10.1001/jamainternmed.2015.3056