Clinical course, characteristics and prognostic indicators in patients presenting with back and leg pain in primary care. The ATLAS study protocol oleh Konstantinou Kika, Beardmore Ruth, Dunn Kate M, Lewis Martyn, Hider Samantha L, Sanders Tom, Jowett Sue, Somerville Simon, Stynes Siobhan, van der Windt Danielle AWM, Vogel Steven, Hay Elaine M