OBJECTIVES: Patients with moderate-to-severe chronic low back pain (CLBP) who are treated with Buprenorphine Transdermal System (BTDS) experience improvements in three patient-reported outcomes: quality of life (QoL), sleep quality, and functioning. This analysis compared the relative responsiveness of measures of each outcome to treatment and treatment-driven changes in pain. METHODS: This post-hoc analysis used data from an enriched, 12-week double-blind, randomized placebo-controlled trial evaluating BTDS (10 or 20 mcg/hour) for treatment of pain in opioid-naive patients with moderate-to-severe CLBP. The trial repeatedly assessed QoL (SF-36v2), sleep quality and problems (Medical Outcomes Study Sleep Scale [MOS-SS]), and functional disability (Oswestry Disability Index [ODI]) in addition to measures of pain.  Responsiveness of each instrument to treatment and changes in pain were examined using analysis of covariance, t-tests, and effect sizes for comparison of effects of time, treatment, and magnitude of pain reduction. The interrelation among PROs was also examined.   RESULTS: The SF-36v2 and ODI showed better responsiveness to treatment and changes in pain than did the MOS-SS. Among subscales of the MOS-SS, only Disturbance showed substantial correlations with other PRO and pain measures and substantial differences across time, treatment, and pain reduction status groups. Several of the QoL domains measured by the SF-36v2, particularly Bodily Pain, Physical Functioning, Role Physical, Social Functioning, and Vitality, showed considerable responsiveness to treatment and pain. For the ODI, the Pain Intensity subscale showed the greatest responsiveness, with the majority of the remaining subscales showing more moderate, but still meaningful, levels of responsiveness. PRO measures were, in general, moderately inter-correlated, particularly between SF-36v2 and ODI subscales.   CONCLUSIONS: Pain subscales on the SF-36v2 and ODI showed the greatest responsiveness to treatment. Substantial responsiveness was also observed for the majority of QoL and functioning domains, as well as sleep disturbance.  Subscales of PRO instruments were generally moderately inter-correlated.