Evidence for a biopsychosocial influence on shoulder pain: pain catastrophizing and catechol-O-methyltransferase (COMT) diplotype predict clinical pain ratings - George, S Z; Wallace, M R; Wright, T W; Moser, M W; Greenfield, W H, 3rd; Sack, B K; Herbstman, D M; Fillingim, R B (Pain, 2008)