The global burden of low back pain: estimates from the Global Burden of Disease 2010 study - Hoy, D; March, L; Brooks, P; Blyth, F; Woolf, A; Bain, C; Williams, G; Smith, E; Vos, T; Barendregt, J; Murray, C; Burstein, R; Buchbinder, R (Ann Rheum Dis, 2014)