Long-term, non-specific spinal pain: reliable and valid subgroups of patients.

The aim of this study was to identify reliable and valid subgroups of spinal pain patients, using data from the Swedish version of the Multidimensional Pain Inventory (MPI-S). A second aim was to test the generalisability of the three patient profiles described in earlier studies on the MPI ("adaptive coper", "dysfunctional" and "interpersonally distressed" patients). The study base consisted of two samples of individuals suffering from long-term, non-specific spinal pain and the results were validated across these samples. Cluster analysis was used to detect distinct groups of patients and the validity of these subgroups was evaluated on variables not used to generate the cluster solution. One subgroup was characterised by lower pain severity, lower interference with everyday activities, lower affective distress and higher life control than the other two subgroups. This patient profile was similar to the MPI adaptive coper patients. A second subgroup resembled the dysfunctional patient profile, thus displaying a worse adjustment to chronic pain than the AC patients. The third patient group reported significantly lower levels of social support from "significant others" than the other subgroups. This patient profile was similar to that of the interpersonally distressed patient group. Taken together, the results support the reliability, validity and generalisability of three subgroups of chronic pain patients derived from the MPI-S.