Effectiveness of duloxetine for remnant pain relief in patients with rheumatoid arthritis despite remission

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory disorder that causes swelling and pain in the joints. Pain management for RA becomes easier if patients are in clinical remission, although some may experience remnant pain despite adequate disease control. Duloxetine, a potent serotonin and norepinephrine reuptake inhibitor, has demonstrated pain relief effects in patients with osteoarthritis; however, the effectiveness of duloxetine for pain in patients with RA in clinical remission has not been investigated. The purpose of this study was to evaluate the efficacy of duloxetine for remnant pain in patients with RA in clinical remission This retrospective study included RA patients from a single institute in Japan from January 2011 to September 2019. Patients with RA who had a visual analog scale (PS-VAS) score > 30 mm and Clinical Disease Activity Index (CDAI) score ≤ 2.8 were selected and were grouped depending on whether duloxetine was administered (G-D) or not (G-C). Variables such as PS-VAS, patient’s global assessment (PGA), C-reactive protein (CRP), CDAI, Simplified Disease Activity Index (SDAI), modified Health Assessment Questionnaire (mHAQ), and quality of life (QOL) score were measured at the initiation of duloxetine and at the first CDAI remission in the G-D and G-C groups, respectively. Thereafter, the variables were measured at week 12. Changes in PS-VAS were compared as a primary outcome using the one-sample t test for each group. Differences between the two groups were evaluated using the Mann–Whitney U test. A total of 306 patients (G-C = 238; G-D = 68) were evaluated. PS-VAS, mHAQ, and QOL scores in both groups improved at week 12 from baseline, in which these scores in the G-D group demonstrated significantly higher improvements than those observed in the G-C group. At week 12, although CDAI scores significantly increased from baseline in both groups, patients were considered to have low disease activity. Duloxetine treatment in patients with RA in clinical remission appears to have comparable effectiveness on relieving remnant pain, improving activities of daily living and maintaining QOL. Duloxetine is not expected to have any effects on disease activity control.