Perceived injustice in fibromyalgia: psychometric characteristics of the Injustice Experience Questionnaire and relationship with pain catastrophising and pain acceptance.
OBJECTIVE
To validate a Spanish version of the Injustice Experience Questionnaire (IEQ), a measure of perceived injustice, in a fibromyalgia sample and to examine its relationship with pain catastrophising and pain acceptance.


METHODS
The IEQ was administered along with the Pain Visual Analogue Scale, the Fibromyalgia Impact Questionnaire, the Hospital Anxiety and Depression Scale, the Pain Catastrophizing Scale (PCS) and the Chronic Pain Acceptance Questionnaire (CPAQ) to 250 primary care patients with fibromyalgia.


RESULTS
The IEQ had good test-retest reliability (intraclass correlation coefficient=0.98) and internal consistency (Cronbach's α=0.92). The factor structure obtained was similar to the original validation study. The multiple regression analyses showed that perceived injustice (PI) accounted for significant pain-related outcomes after controlling pain intensity, PCS and CPAQ. Principal component analysis of both the IEQ and the CPAQ taken together showed that the two constructs do not represent opposite extremes of the same dimension.


CONCLUSIONS
The IEQ is a reliable assessment tool for measuring PI among patients with fibromyalgia. PI seems to be distinct from catastrophising, although the two constructs are very similar. The factor analysis showed that PI and acceptance represent related constructs, and this entails relevant implications for therapy, as acceptance-based interventions would be appropriate.
Clínica Rodero, Santander, Spain.
Baltasar
B
Rodero
Juan V
JV
Luciano
Jesús
J
Montero-Marín
Benigno
B
Casanueva
Juan Carlos
JC
Palacin
Margalida
M
Gili
Yolanda
Y
López del Hoyo
Antoni
A
Serrano-Blanco
Javier
J
Garcia-Campayo
D000328:Adult; D000368:Aged; D001007:Anxiety / Q000523:psychology; D001519:Behavior; D058443:Catastrophization / Q000523:psychology*; D003863:Depression / Q000523:psychology; D005163:Factor Analysis, Statistical; D005260:Female; D005356:Fibromyalgia / Q000523:psychology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement / Q000523:psychology; D010465:Perception; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D057566:Self Report; D012935:Social Justice; D011795:Surveys and Questionnaires