Clinical characteristics of chronic back pain as a function of gender and oral opioid use

Study Design. A cross-sectional analysis of data derived from patients with chronic spinal pain undergoing evaluation at a multidisciplinary pain treatment center was conducted. Objective. To determine whether pain severity, psychological status, and physical disability differed as a function of gender and opioid use, and whether the clinical correlates of opioid use differed in women and men with chronic back pain. Summary of Background Data. Gender differences in the experience of pain have been widely reported. For example, in the general population, several chronic pain conditions are more prevalent among women than among men, and many experimental studies demonstrate lower pain thresholds and tolerances among women. In addition, recent evidence from studies of experimental and acute clinical pain suggests that responses to analgesic medications may differ in women and men. Methods. The sample consisted of 240 patients (35% women) with low back, upper back, or neck pain undergoing evaluation for treatment at a multidisciplinary pain center. The patients were classified as opioid or nonopioid users on the basis of self-report and medical record review. All the patients completed a battery of clinical assessments, including measures of pain severity, psychological adjustment, self-reported disability, functional tasks, and pain tolerance. Analyses were conducted to examine clinical variables as a function of gender and opioid use. Results. The results indicated that opioid use was associated with greater self-reported disability and poorer function in both women and men. However, the association of opioid use with affective distress differed between women and men. The women using opioids showed lower affective distress, whereas the opioid-using men reported greater affective distress. Opioid use was not associated with pain severity, although the women reported greater pain than men. Conclusions. These findings indicate that both opioid use and gender are significant predictors of clinical status of patients with chronic spinal pain. More interesting, these two variables interact because opioid use was associated with increased affective distress among the men, but the reverse was true for the women, In addition, the women reported greater pain severity, which is consistent with some previous findings. Potential explanations for these findings are presented, and the practical implications are discussed.