Authors' objectives:

This special report examines key methodological elements related to measuring and reporting chronic pain outcomes in RCTs. The report also systematically review studies that attempt to estimate the minimal clinically important difference (MCID) in change in pain intensity among patients with chronic pain.

Authors' results and conclusions: Eighteen important methodological elements related to measuring and reporting chronic pain outcomes in RCTs were identified in five categories: 1) pain intensity scale and assessment of pain; 2) quality of life; 3) global patient assessment of improvement; 4) data analysis; 5) results and conclusions. Overall in the systematic review of both NRS and VAS studies, there was a high degree of methodological heterogeneity precluding comparisons across studies. The pain states rated were either not described or varied in the activity, span of time and whether extreme or average intensity was of interest. More importantly, there was large variation in the manner external criterion scales were used to define clinically significant change in estimating the MCID. Therefore, it was not possible from this evidence to define an MCID for reporting trial results of chronic pain.

Authors' recommendations: Defining the effectiveness of interventions ameliorating pain and its consequences poses challenges in designing, conducting, analyzing, and reporting of RCTs. Critically appraising these RCTs presents similar challenges. Owing to some unique aspects of chronic pain outcomes, methodological issues are encountered that do not always allow straightforward interpretation. Furthermore, methods used to define the MCID in chronic pain and estimates derived vary considerably. Due to heterogeneity in methods, the body of evidence does not permit conclusions about the clinically significant magnitude of change in NRS- or VAS-assessed pain among chronic pain patients. A range of MCIDs for chronic pain may be more plausible than a single consistent value across severity and causes of pain. Because of the unique characteristics of chronic pain, it is important to approach appraisal of evidence from a context not always encountered in other settings. Making assumptions explicit and addressing the potentially problematic aspects of RCTs having chronic pain outcomes, especially the MCID, can facilitate better critical appraisal of intervention effectiveness.

Authors' methods: Review

Project Status: Completed

URL for project: http://www.bcbs.com/blueresources/tec/contact-tec.html

Year Published: 2006

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: BlueCross BlueShield Association

Contact Address: BlueCross BlueShield Association, Technology Evaluation Center, 225 North Michigan Ave, Chicago, Illinois, USA. Tel: 888 832 4321

Contact Name: tec@bcbsa.com

Contact Email: tec@bcbsa.com

Copyright: BlueCross BlueShield Association (BCBS)