Association between opioid use disorder and blunted heart rate variability among opioid-treated chronic pain patients.

Given the severity of the ongoing opioid epidemic, it is essential to understand the mechanisms of risk for development and maintenance of opioid use disorder (OUD). The aim of the current large-scale psychophysiological investigation was to test whether patients with OUD had lower resting-state high-frequency heart rate variability (HF-HRV) than those without OUD, controlling for sociodemographic and clinical confounds. Additionally, we tested whether HF-HRV was associated with opioid craving in this population. Participants in this cross-sectional study were 490 chronic pain patients (50.4% female) treated with long-term opioid therapy. OUD diagnosis was determined by psychiatric interview. HF-HRV was measured at resting baseline. We computed the association between OUD and resting-state HF-HRV, controlling for age, gender, race, pain severity, emotional distress and opioid dose. Opioid craving was measured with visual analogue scales to assess whether HF-HRV was associated with craving. Results showed that resting HF-HRV was significantly lower for patients with OUD than for those without OUD (p < 0.001, d = 0.36), indicating deficits in autonomic flexibility. OUD diagnosis (p = 0.002) and OUD severity (p = 0.03) were associated with lower HF-HRV in regression models accounting for a range of confounders. Additionally, lower HF-HRV was significantly (but weakly) correlated with heightened opioid craving (r = -0.166, p < 0.001). Overall, findings suggest that resting-state HF-HRV may serve as a valid biomarker of addiction among people on long-term opioid therapy.