Correlations between fibromyalgia symptom and function domains and patient global
impression of change: a pooled analysis of three randomized, placebo-controlled
trials of pregabalin.
Author(s): Arnold LM, Zlateva G, Sadosky A, Emir B, Whalen E.
Affiliation(s): Women's Health Research Program, Department of Psychiatry and Behavioral
Neuroscience, University of Cincinnati College of Medicine, Cincinnati, Ohio,
Publication date & source: 2011, Pain Med. , 12(2):260-7
OBJECTIVE: The objective of the study was to conduct an analysis of pooled data
from pregabalin fibromyalgia clinical trials to determine which fibromyalgia
symptom and function domains drive patient perception of improvement.
DESIGN: Data from three double-blind, placebo-controlled trials of pregabalin in
fibromyalgia patients were pooled for this analysis. Changes in independent
variables, including the Medical Outcomes Study 36-item Short-Form Health Survey,
Medical Outcomes Study-Sleep Scale, sleep quality score from the daily sleep
diary, pain score from the daily pain diary, Fibromyalgia Impact Questionnaire,
and Multidimensional Assessment of Fatigue were analyzed as predictors of outcome
on the dependent variable, Patient Global Impression of Change (PGIC).
Correlation analysis assessed relationships between the independent variables and
PGIC. Cluster analysis identified dependencies among variables, and a shrinkage
and selection method and stepwise logistic regression determined rank order of
RESULTS: Improvement in PGIC at endpoint showed highest correlation with pain
improvement, fatigue, sleep, and work and physical function (0.4 < r < 0.6).
Cluster analysis identified three main clusters of symptoms at endpoint: mood
(anxiety and depression), pain and sleep, and function and fatigue. Pain was
ranked as the most important outcome explaining variability in PGIC, followed by
fatigue and sleep.
CONCLUSIONS: Pain, fatigue, and sleep associate most strongly with improvement in
PGIC. Physical- and work-related function also correlated with patients' overall
assessment of improvement. These domains and their respective outcome measures
can be used to improve assessment of patients' response to treatment.