Brennan JM, Peterson ED, Messenger JC, Rumsfeld JS, Weintraub WS, Anstrom KJ, Eisenstein EL, Milford-Beland S, Grau-Sepulveda MV, Booth ME, Dokholyan RS, Douglas PS. Linking the National Cardiovascular Data Registry CathPCI Registry with Medicare claims data: validation of a longitudinal cohort of elderly patients undergoing cardiac catheterization. Circ Cardiovasc Qual Outcomes. 2012 Jan; 5(1):134-40.