The journal of pain : official journal of the American Pain Society
-
Randomized Controlled Trial Comparative Study
Comparing counterconditioning and extinction as methods to the reduce fear of movement-related pain.
Cognitive-behavioral treatments for chronic pain typically target pain-related fear; exposure in vivo is a common treatment focusing on disconfirming harm expectancy of feared movements. Exposure therapy is tailored on Pavlovian extinction; an alternative fear reduction technique that also alters stimulus valence is counterconditioning. We compared both procedures to reduce pain-related fear using a voluntary joystick movement paradigm. Participants were randomly allocated to the counterconditioning or extinction group. During fear acquisition, moving the joystick in 2 directions (conditioned stimulus [CS+]) was followed by a painful electrocutaneous stimulus (pain-unconditioned stimulus [US]), whereas moving the joystick in 2 other directions was not (CS-). During fear reduction, 1 CS+ was extinguished, but another CS+ was still followed by pain in the extinction group; in the counterconditioning group, 1 CS+ was extinguished and followed by a monetary reward-US, and another CS+ was followed by both USs (pain-US and reward-US). The results indicate that counterconditioning effectively reduces pain-related fear but that it does not produce deeper fear reduction than extinction. Adding a reward-US to a painful movement attenuated neither fear nor the intensity/unpleasantness of the pain. Both procedures changed stimulus valence. We contend that changing the affective valence of feared movements might improve fear reduction and may prevent relapse. ⋯ This article reports no immediate differences between counterconditioning and extinction in reducing pain-related fear in the laboratory. Unexpectedly, both methods also altered stimulus valence. However, we cautiously suggest that methods explicitly focusing on altering the affective valence of feared movements may improve the long-term effectiveness of fear reduction and prevent relapse.
-
Randomized Controlled Trial
Treatment of Postherpetic Neuralgia with Gastroretentive Gabapentin: Interaction of Patient Demographics, Disease Characteristics, and Efficacy Outcomes.
To understand how patient demographics and patient-reported disease characteristics relate to successful management of postherpetic neuralgia (PHN), integrated data from phase 3 and phase 4 studies of patients with PHN (n = 546) who received once-daily gastroretentive gabapentin (G-GR, 1800 mg) were analyzed. There were widespread, networked, positive correlations among efficacy end points--pain qualities on the visual analog scale (VAS) and Brief Pain Inventory (BPI), measures of pain interference on the BPI, and Patient Global Impression of Change (PGIC)--most likely characterized by positive feedback loops, in which pain interferes with patient functioning, and poor functioning enhances pain. VAS scores at baseline or at week 2 were the strongest predictors of being "much" or "very much" improved on the PGIC; BPI sleep interference scores were the strongest predictors of percent changes in BPI pain qualities and in the average of BPI interference scores, whereas age, sex, and race were not important predictors. In addition to VAS, BPI sleep interference and PGIC assessments appeared to be key co-strategic factors important for successful treatment outcomes, and should be considered as co-primary end points in future clinical trials of PHN. This could improve detection of true positive efficacy responses and guide successful transition to real-world clinical practice. ⋯ This study describes complex relationships among measures of pain intensity, pain interference with daily activities, and demographics of patients with PHN treated with G-GR. Such comprehensive characterization provides important insight into how different variables contribute to successful treatment, and may lead to better management of neuropathic pain.