BPI-S and BPI-I are self-reported scales measuring severity of pain and interference on function, respectively. Severity scores ranged from 0 (no pain) to 10 (severe pain) for each question assessing worst pain, least pain, and pain right now. Interference scores ranged from 0 (does not interfere) to 10 (completely interferes) for each question assessing interference of pain in past 24 hours with general activity, mood, walking ability, normal work, relations with other people, sleep, and enjoyment of life. Average interference was the average of non-missing scores of individual interference items. LS mean was calculated using an MMRM approach including administration groups, observation points, and interaction between the administration groups as fixed effects, and baseline as well as the presence or absence of major depressive disorder as covariates; a linear model with unstructured error variance was applied.