Self-reported Fear, Psychological Inflexibility and Opioid Dose in Relation to Pain

Within the past two decades, research on the treatment of chronic pain with opioid medication has attempted to understand the complex relationship between psychological factors, subjective pain experience, and prescription opioid use. Specifically, fear and psychological inflexibility factors have been explored in relation to both pain sensation and opioid dose. The current study aims to explore and enhance the understandings of brief, subjective self-report measures of fear in relation to opioid dose, subjective fear, self-reported pain, and psychological inflexibility processes. This study examined whether (1) a quadratic relationship would exist between pain scores and opioid dose; (2) individuals with higher opioid dosages would have higher psychological inflexibility scores and subjective fear of pain scores; (3) subjective fear scores, in concert with psychological inflexibility pain measures, would be predictive of pain scores, and (4) subjective fear scores would positively correlate to psychological inflexibility pain measures. The final sample consisted of 202 respondents of an online survey for chronic pain. Survey measures included the Chronic Pain Grade questionnaire (CPG), the Psychological Inflexibility in Pain Scale (PIPS), Subjective Fear of Pain when in Low Pain (FlowP), and when in No Pain (FnoP). Opioid dosage for each participant was converted to the standardized Morphine Milligram Equivalent (MME). A significant quadratic relationship between the CPG and MME was found (p=0.016). MME scores were ns in relation to Subjective Fear of Pain scores or PIPS. FlowP and FnoP, however, did predict overall pain scores for participants (p<0.001). Overall pain scores also showed a positive moderate relationship with overall PIPS scores (r(200)=0.673, p<0.001). FlowP and PIPS together explained 45.7% of the variance of pain scores (F(2,199) = 83.640, p=0.003, R=0.676, R2=0.457) with FnoP and PIPS explaining slightly less at 44.8% (F(2,187)=76.002, p<0.001, R=0.670, R2=0.448). FlowP, however, showed slightly stronger correlations to overall PIPS scores (r(200)=0.648, p<0.001) when compared to FnoP (r(188)=0.589, p<0.001). These findings support previous research indicating a quadratic relationship between pain and opioid dose. Higher pain scores were correlated to higher scores on PIPS and subjective fear of pain questions. Of benefit, the subjective fear of pain questions showed some minor predictability when used as a two-question predictor of pain. Our results not only support previous research underlying the relationship between opioid dose and pain but expand on insight into the use of short-form, fear-related questions to predict psychometrics such as psychological inflexibility and pain sensation.