Dimensions of the impact of cancer pain in a four country sample: new information from multidimensional scaling

We investigated the question of how cultural and linguistic backgrounds affect relationships among ratings (reported by patients with metastatic cancer) of pain's interference with such functions as activity, mood, and sleep. Multidimensional scaling (MDS) was used to analyze ratings of pain interference from a sample consisting of four culturally and linguistically different groups from the US (n = 1106), France (n = 324), the Philippines (n = 267), and China (n = 146). Patients all completed the Brief Pain Inventory, a self-report measure of pain and its interference with function. For each of these samples, MDS solutions consistently revealed two interpretable dimensions. In all samples, one dimension represented affect and the other dimension represented activity. The dimensions were consistently interpretable across all four samples and across three levels of pain severity ('mild', 'moderate', and 'severe'). The dimensions were most prominent when pain was moderate, rather than mild (when little interference was produced) or severe (when all domains were highly interfered with). These dimensions may have utility in the study of the epidemiology of pain and of the effectiveness of pain treatment. They may also be useful in clinical assessment to describe different patterns of pain interference.