Clinical trials on the treatment of pain syndromes have adopted Patient Global Impression of Change (PGIC) as a primary outcome. However, little is known about how change in clinical status influences these ratings. The present study examined relationships between changes in pain, depressed mood, physical functioning, vitality, sleep disturbance, cognitive complaints, and PGIC ratings among 1260 participants with fibromyalgia (FM) who completed one of two trials examining the safety and efficacy of milnacipran. Many of the relationships between change in clinical status and PGIC ratings were stronger among persons who rated themselves as improved (responders) versus those reporting no change or a worsening of their condition (non-responders). Among non-responders, simultaneous regression analysis revealed that greater degrees of depressed mood and pain, and poorer physical function were significantly associated with worse PGIC ratings. Among responders, improvements in pain were significantly associated with better PGIC ratings, along with improvements in vitality, sleep, physical function, and cognitive complaints. These findings underscore the complexity of global ratings in FM patients, and suggest the association between clinical status and PGIC ratings varies as a function of perceived treatment response. Several domains were associated with PGIC ratings, highlighting the need to assess multiple outcomes in clinical trials of treatments for FM.
Copyright 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.