“…Several studies using different approaches to search for subgroups among CLBP patients were found. Solovieva et al [59], Tegeder et al [60], Karpinnen et al [61], Costigan et al [62] for example, found subgroups based on genetic factors, while Turk et al [63], Turk [64], Dahlstrom et al [65], Turk et al [66], Johansson et al [67], Turk et al [68], Soderlund et al [69], Thieme et al [70], Widerström-Noga et al [71], Heidari et al [72] found subgroups based on psychosocial factors, and Huijen et al [73], McCracken et al [74], Hasenbring et al [75] based subgroups on activity-related behavior. As all CLBP patients had a back pain diagnosis in common, it seemed logical to cluster these patients based on their pain characteristics as well as psychological and social factors, as was done by Waddell [7], Hasenbring et al [75], Foster [76], Kamper [77], and Wettstein et al [78] in various previous cluster analyses.…”