Retrospective assessment of resource use and costs in two investigator-initiated randomized trials exemplified a comprehensive cost item list by Speich, B, Von Niederhäusern, B, Blum, CA, Keiser, J, Schur, N, Fürst, T, Kasenda, B, Christ-Crain, M, Hemkens, LG, Pauli-Magnus, C, Schwenkglenks, M, Briel, M