Opioids in non-cancer pain: Depression and pain: the relationship between chronic low back pain, depression, and opioid therapy

Abstract

Depression and chronic pain are highly prevalent and co-morbid conditions. Treatment of co-morbid depression has been shown to improve the outcomes of several medical conditions; if the same were true for chronic pain this could imply that treatment of depression may improve the outcomes of opioid or other analgesic treatments. The objective was to compare pain outcomes – specifically health-related quality of life (HRQoL) scores - in chronic pain patients, stratified by the presence or absence of depression. Six month, open-label, randomized, multicenter, two-way cross-over study of 229 subjects with chronic non-cancer low back pain. Patients received transdermal fentanyl for three months followed by treatment with oxycodone/acetaminophen for three months, or vice versa. Depression was defined with two criteria: a score of <42 on the SF-36 mental health scale; and a score of ≥18 on the Beck Depression Inventory (moderate depression). HRQoL outcome scores (based on modified TOPS and SF-36) were compared based on depression status. Significance testing consisted of Student t-tests for continuous change scores and chi-square tests for categorical changes. Both depressed and non-depressed patients treated with either transdermal fentanyl or oxycodone/acetaminophen showed significant improvement in several HRQoL outcomes, whether using the SF-36 or BDI definition. Relative to depressed patients, non-depressed patients showed significantly greater improvement in physical functioning (p=0.049), vitality (p=0.035), social functioning (p=0.029), mental health (p=0.022), and the physical summary scale (p=0.039). Improvements on the TOPS perceived disability and total pain summary scales reached statistical significance (p=0.004, and p=0.005, respectively). Patients on concomitant antidepressants experienced greater improvements in SF-36 physical and mental summary scales and the TOPS total pain summary. Treatment of chronic low back pain may be compromised by the presence of co-morbid depressed mood. Further research is warranted to compare the outcomes of various pain populations while stratifying by depression status and treatment.