Estimation of minimum clinically important difference for pain in fibromyalgia.
Philip J Mease1, Michael Spaeth, Daniel J Clauw
1Swedish Medical Center and University of Washington School of Medicine, Seattle, USA. pmease@philipmease.com
Arthritis Care & Research
|February 12, 2011
Summary
The minimum clinically important difference (MCID) for fibromyalgia pain measures using the Brief Pain Inventory (BPI) is approximately 2 points. This represents a 30-35% improvement, aiding clinical trial design.
Area of Science:
- Rheumatology
- Clinical Pharmacology
- Pain Medicine
Background:
- Fibromyalgia is a chronic condition characterized by widespread pain.
- The Brief Pain Inventory (BPI) is a common tool for assessing pain severity.
- Establishing a minimum clinically important difference (MCID) is crucial for interpreting treatment effects.
Purpose of the Study:
- To determine the MCID for BPI pain measures in fibromyalgia patients.
- To provide benchmarks for evaluating treatment efficacy in clinical trials.
Main Methods:
- Pooled data from 4 randomized, double-blind, placebo-controlled trials of duloxetine for fibromyalgia.
- Anchor-based MCID estimation using the Patient's Global Impressions of Improvement scale.
- Analysis of BPI average pain item and BPI severity scores.
Main Results:
- Anchor-based MCIDs were 2.1 points for BPI average pain and 2.2 points for BPI severity.
- These MCIDs correspond to 32.3% and 34.2% reductions in pain scores, respectively.
- MCIDs were consistently around 2 points, indicating a 30-35% improvement.
Conclusions:
- MCIDs for BPI pain measures in fibromyalgia are approximately 2 points.
- This signifies a 30-35% improvement from baseline.
- These values can guide the design of future clinical trials assessing pain improvements in fibromyalgia.
