Prospective evaluation of chronic pain disorders and treatments

Background: The incidence of chronic pain is variable among individuals who have sustained traumatic or surgical injury. Also, treatments for pain rarely are effective consistently for a procedure or agent, and no therapies are considered effective for pain that is chronic.

New method: Difficulties with standard methods for conducting clinical trials call attention to a need for protocols that provide a new understanding of the development of and control over chronic pain. Prospective single-subject research designs can document varieties of pain progression over time for individuals. Subsequent grouping of individuals with common characteristics directs a mechanism-based approach to therapy.

Results: Tracking of individuals' pain and associated influences over time is consistent with clinical practice, noting and adapting to changes that occur.

Comparison with existing methods: Grouping patients with diverse characteristics and variable effects of therapy is problematic. Conventional evaluation of pain assesses patients with similar injuries or surgery without characterizations of individuals who develop chronic pain or recover over time. Also, classical evaluation of therapies involves comparison of groups receiving treatment or a placebo without characterization of patients with successful and unsuccessful results.

Conclusions: Single-subject prospective studies can inform clinical trials according to individual differences that would be obscured by comparison of groups with unknown variation in characteristics that influence pain and therapeutic effectiveness.