Development of DEMQOL-U and DEMQOL-PROXY-U: generation of preference-based indices from DEMQOL and DEMQOL-PROXY for use in economic evaluation oleh B Mulhern, D Rowen, J Brazier, S Smith, R Romeo, R Tait, C Watchurst, K-C Chua, V Loftus, T Young, D Lamping, M Knapp, R Howard, S Banerjee