Pre-treatment Level of Opioid Use as a Predictor of Chronic Pain Rehabilitation Outcome

The current study examines the relationship between pre-treatment opioid use and treatment outcomes among 1,226 chronic pain patients who participated in a functional restoration program. Patients were divided into five categories based on self-reported pre-treatment level of opioid use. Patients received an initial evaluation prior to treatment, which included a physical examination, medical history, disability assessment interview, quantitative functional capacity evaluation, and psychological intake interview. During the initial weeks of treatment, patients consented to and were weaned from all opioid medications. Assessments were repeated at program completion, and a structured telephone interview was conducted at one-year post-treatment to evaluate socioeconomic outcomes. Nearly half of the patients (596/1226) reported opioid use upon admission. Pre-treatment opioid dose, though, was not associated with clinically significant differences in pre-treatment socioeconomic variables, pain report, self-reported disability, or health-related quality of life. At pre-treatment, only patients taking the highest opioid doses showed greater self-reported depressive symptoms. Clinician-rated depressive symptoms did not differ significantly based on opioid dose. Opioid use was associated with pre-treatment health variables, with patients taking opioids being one and a half times more likely to report a prior work-related injury and a pre-treatment surgery. Higher levels of opioid use were associated with more severe psychopathology, as demonstrated in less desirable MMPI profiles. Contrary to expectation, level of pretreatment opioid use did not play a significant role in post-treatment outcomes related to gains in physical functioning, pain report, self-reported disability, or health related quality of life. In general, opioid users showed similar gains relative to non-opioid users from completing functional restoration. However, opioid users showed significantly lower work return and work retention rates, and higher rates of new surgery and healthcare utilization at a one-year follow-up. Pre-treatment opioid dose was also inversely related to program completion rates. Results suggest that compared to nonopioid users, patients who discontinue opioid use show similar post-treatment benefits from functional restoration, but poorer socioeconomic outcomes. Thus, level of pretreatment opioid use could be a useful guide for identifying patients who are at risk, and targeting treatment interventions to improve the likelihood of program completion and positive long-term treatment outcomes.