Predictors of Functional Outcomes Among Chronic Pain Patients Receiving Long-Term Opioid Treatment

Background. Little is known about the relationship between long-term opioid therapy and functional status among chronic pain patient populations. This paper examines the role of substance use, mental health conditions, and demographic characteristics in determining functional disability among long-term opioid therapy patients. Methods. 972 adult Kaiser Permanente Northern California (KPNC) members who were chronic, non-cancer pain patients receiving long-term opioid therapy, stratified by dosage levels, completed a telephone survey that measured functional outcomes with the disability interference score from the Graded Chronic Pain Scale Version 2.0. Results. Multiple logistic regression analyses found that higher depression severity was associated with greater disability (OR = 5.713 for Dose 1, OR = 4.604 for Dose 2, both p<.05), as was lower income (OR = 2.512 for Dose 3). Employment was predictive of lower disability (OR = 0.492 for Dose 1, OR = 0.299 for Dose 2, and OR = 0.168 for Dose 3, all p<.05), as was higher educational attainment (OR = 0.417 for Dose 2, p<.05). Current alcohol use was not related to higher disability, and having a history of a substance use problem predicted lower disability (OR=0.388 for Dose 2, p<.05). Our findings are consistent with others in the literature suggesting a relationship between depression and disability, and between low socioeconomic status and disability, in chronic pain patients. This study suggests a need for careful depression screening of chronic pain patients, and suggests there may be great benefits from integrating depression and pain treatments.