Comment on Evelmo etal.: Reward responsiveness in patients with chronic pain.

Abstract

In November 2015, The European Journal of Pain published an article titled “Reward Responsiveness in Patients with Chronic Pain” by Elvemo, Landrø, Borchgrevink and Håberg. With this letter I would like to bring to the authors’ attention possible improvements that could have been done in this study. Before I address these issues, I would like to commend the authors for producing relevant and informative research on the reward responsiveness of patients with chronic pain. The knowledge gained in their research indicates that reduced reward responsiveness could be a potential marker of chronic pain. This has implications for future pharmacological treatments. Elvemo et al. (2015) studied reward responsiveness with several scales including the BIS/BAS scale, the Drive subscale, the Reward Responsiveness scale and the Fun Seeking scale. The authors found that chronic pain patients had a reduction in reward responsiveness, which demonstrates a lower sensitivity to the occurrence or anticipation of reward. The two neural systems measured in the BIS/BAS scale are motivational pathways that regulate sensitivity to punishment (BIS) and reward (BAS) and it is found that an irregular score on these scales is related to psychopathology (Scholten et al., 2006). Although there is evidence supporting the utility of these scales, the two scales have faced conceptual and psychometric critiques. Research states that the BAS scale does not consist of a single measurement factor and cannot be representative of just reward responsiveness. The researchers also measured Fun Seeking, and this is, however, related to impulsivity and not reward responsiveness (Ivo et al., 2010). I am writing this letter to draw the author's attention to a new scale to measure reward responsiveness proposed by Ivo et al.(2010). This scale has been shown to sufficiently address problems in previous reward responsiveness scales such as the BAS/BIS. This new scale has high internal consistency, convergent validity, discriminant validity, test–retest reliability and predictive properties. The creators of this scale also feel like it does a more accurate job measuring the single factor of reward responsiveness unlike other scales like the BIS/BAS. The authors of this new scale feel the BIS/BAS measure other factors in addition to reward responsiveness, which could cause bias. Therefore, I strongly encourage the authors of “Reward Responsiveness in Patients with Chronic Pain” to explore future research with the scale proposed by Ivo et al. (2010).