Do pain qualities and spatial characteristics make independent contributions to interference with physical and emotional functioning?

Although pain is acknowledged to be a multidimensional experience that can vary in intensity, quality (eg, burning, sensitive), and spatial characteristics (eg, location on body, perceived depth), its qualitative and spatial domains continue to be rarely assessed in pain clinical trials. One factor that may be contributing to the relatively rare assessment of pain quality and spatial characteristics is the lack of research addressing whether knowledge about these aspects of pain contributes important information beyond that provided by pain intensity alone. For example, there is no research that has examined whether measures of pain quality and perceived depth add anything to the understanding of the impact of pain on function. In the current study, secondary analyses of pretreatment data from clinical trials of patients from 3 diagnostic groups (osteoarthritis, low back pain, and peripheral neuropathy) indicated that measures of pain quality and perceived depth were significantly associated with pain interference with functioning, independent of global pain intensity and unpleasantness. No single pain descriptor emerged as universally important, however, although the findings suggest that: 1) sharp, deep, and perhaps especially sensitive pain may be important in patients with painful peripheral neuropathy; 2) sharp, sensitive, itchy, deep, and surface pain may be key pain descriptors important to persons with low back pain; and 3) perhaps deep pain may be the sole key pain descriptor important among persons with osteoarthritis. The findings support the potential utility of including measures of specific pain qualities and perceived depth in pain clinical trials and provide an initial empirical basis for determining which pain descriptors may be most closely linked to patient functioning. Perspective: Specific pain qualities, such as sharp, sensitive, and itchy pain, and perceived depth of pain appear to play a significant and unique role in the prediction of pain interference in addition to global pain intensity and unpleasantness. These findings suggest that measures of these specific pain domains could play an important role in understanding the impact of pain on patient functioning. (C) 2006 by the American Pain Society.