Predictors of severe pain in a cohort of 5271 individuals with self-reported neuropathic pain.

The influence of pain descriptors and mechanical hypersensitivity on pain severity in neuropathic pain has not been well researched and is poorly understood. The aim of this study was to determine the relationship between pain severity and other factors describing chronic neuropathic pain in a large cohort of patients with self-reported neuropathic pain potentially recruited as subjects for a Phase IIa study. A questionnaire specific to the study parameters covering demographics and pain characteristics was sent to potential participants. Overall, 9185 questionnaires were returned from potential subjects who self-reported neuropathic pain. Adjusted odds ratios with 95% confidence intervals were used as a measure of association. These were estimated by unconditional logistic regression. Pain descriptors in the questionnaire were: burning, shooting, shocking, and aching. The presence of self-reported allodynia and hyperalgesia was strongly indicative of both moderate and severe pain, with a significant interaction of both factors in moderate and severe pain. Having 3 or 4 pain descriptors was also strongly indicative of both moderate and severe pain. Female gender, age, and history of serious mental disorders were found to be weaker indicators of both moderate and severe pain. Given the large and varied population with many neuropathic pain diagnoses in the study, the findings are not likely to be merely chance, but are likely to reflect important relationships between pain severity and other factors in those who suffer from chronic neuropathic pain.