Madden JM, Graves AJ, Zhang F, Adams AS, Briesacher BA, Ross-Degnan D, Gurwitz JH, Pierre-Jacques M, Safran DG, Adler GS, Soumerai SB. Cost-related medication nonadherence and spending on basic needs following implementation of Medicare Part D. JAMA. 2008 Apr 23; 299(16):1922-8.