Differential relationships between anxiety and treatment-associated pain reduction among male and female chronic pain patients

Objectives: Clinical, epidemiological, and laboratory-based studies have all suggested that female sex and elevated anxiety are associated with greater experience of pain. However, several recent reports have also indicated that sex may moderate the relationship between anxiety and responses to noxious stimuli, with anxiety more strongly related to pain among males. The present study examined whether anxiety differentially impacts outcomes for pain treatment among males and females. Methods: Seventy-four chronic pain patients (34 males, 40 females) completed the Pain Anxiety Symptoms Scale and several other psychologic measures before undergoing a variety of treatment procedures including epidural steroids, trigger point injections, and participation in brief, cognitive-behaviorally oriented psychoeducational groups. Patients provided pre- and post-treatment ratings of pain for all interventions. Results: Consistent with findings from previous investigations, the present study noted stronger relationships between baseline anxiety and pre-treatment pain severity among males relative to females. In addition, while lower levels of baseline anxiety were related to greater treatment-associated pain reduction among females, the reverse pattern emerged for males. These relationships persisted even after controlling for other psychologic factors such as depression, coping style, and hypervigilance. Discussion: These findings suggest differential relationships between anxiety and pain relief as a function of sex. While we are unable to identify a mechanism for this effect, higher anxiety may have predicted more pain relief among males and less pain relief among females due to sex differences in coping strategies or placebo effects.