Exploratory study examining associations between prescription opioid dose and delay discounting in patients with chronic pain

OBJECTIVE: Although some research has identified correlates of high-dose opioid prescriptions, relatively little is known about factors that lead to higher doses. Delay discounting (DD), defined as the subjective value of a reward declining as a function of the delay to that reward, is an objective measure of impulsivity. DD is commonly studied in the context of addictive behaviors, and findings consistently demonstrate greater DD among individuals with opioid use disorders. The authors conducted a preliminary investigation to examine the extent to which DD is associated with prescription opioid dose among patients with musculoskeletal pain. DESIGN: Cross-sectional study. SETTING: A single veterans affairs medical center located in the Pacific Northwest. SUBJECTS: Participants with chronic musculoskeletal pain. The authors identified patients prescribed with high doses of opioids (100 mg morphine equivalent per day [MED] or more; n = 17), traditional doses of opioids (5-99 mg MED; n = 34), and patients with pain who were not prescribed opioids (n = 24). METHODS: All participants completed a battery of self-report measures assessing demographic characteristics, pain-related variables, and psychiatric symptoms. Participants also completed a computerized DD task. RESULTS: DD was negatively correlated with average daily opioid dose (p = 0.003) and positively correlated with anxiety (p = 0.013). In a multivariable regression analysis, after controlling for the effects of demographic and clinical factors, DD was significantly associated with prescription opioid dose. CONCLUSIONS: Contrary to study expectations, higher opioid dose was associated with less DD. These findings call for prospective research to further elucidate the relationships between DD and other measures of impulsivity and prescription opioid doses.