Objective: To assess the validity of an exposure score obtained from the Xm2 tool for all pharmacological and nonpharmacological strategies used by individuals to manage chronic pain.
Methods: Using data from individuals with chronic pain, eXposure multimodal (Xm2) scores were calculated by assigning one point for every 100 mg of morphine equivalent used (opioid medications); 25% of the maximum recommended exposure used (nonopioid medications); and any use of another strategy then summed. Content, criterion, construct, and convergent validity were assessed.
Results: The sample of 149 individuals used a mean of 12.6 (SD = 4.6) strategies to manage pain and had a mean Xm2 score of 16.8 (SD = 9.1). Content validity was established by demonstrating that the pain management strategies identified were also reported in the literature. Criterion validity was established by the positive association of exposure scores with the following: interference with work (odds ratio (OR) = 2.23, 95% confidence interval (CI) = 1.14-4.36), daily activities (OR = 2.10, CI = 1.07-4.13), relationships (OR = 1.98, CI = 1.01-3.88), and leisure activities (OR = 2.31, CI = 1.18-4.50); workdays missed (OR = 5.10, CI = 1.92-13.58); emergency department visits (OR = 3.40, CI = 1.17-9.91); hospitalizations (OR = 4.18, CI = 0.86-20.37); and by a negative association with satisfaction (OR = 0.40, CI = 0.18-0.88). Construct validity was established by the positive association of exposure with baseline pain intensity (p < 0.01) and odds of experiencing an adverse event (OR = 2.31, CI = 1.18-4.52). Convergent validity was established through correlations of pain intensity from the Xm2 score and existing quantitative analgesic questionnaire (QAQ) score.
Discussion: Xm2 scores represent a valid estimate of total exposure to multimodal strategies used and provide clinically relevant information for deciding what strategies to use at what level.