1. University of Aberdeen; Health Services Research Unit; Polwarth Building, Foresterhill Aberdeen UK AB25 2ZD
2. Univ. of Aberdeen; Dept. of Publ. Health; Polwarth Building Foresterhill Aberdeen Scotland UK AB 25 2 LT
3. St Antonius Ziekerhuis; Dept. of Chirurgie; Postbus 2500 EM Nieuwegein Netherlands 3430 EM
4. Mount Sinai Hospital and Samuel Lunenfeld Research Institute; Toronto Canada
5. University of Aberdeen; School of Medicine; 1st Floor, Health Sciences Building Foresterhill Aberdeen Scotland UK AB25 2ZD