Psychometric properties of a new treatment expectation scale in rheumatoid arthritis: an application of item response theory.
BACKGROUND
Patient-generated health outcome measures are important in the assessment of long-term treatment goals for Rheumatoid Arthritis (RA), but few psychometrically sound measures are available. The MAPLe-RA (Measuring Actual Patient-Led expectations in RA) is a new questionnaire and its psychometric properties are not investigated. This study aims to examine these properties for each of the items using Item Response Theory (IRT) .


METHODS
Participants were included if they completed the scale (MAPLe-RA). A one parameter (Rasch) model and a two parameter logistic (2PL) model were applied to these data using M-plus software.


RESULTS
One hundred thirty-eight patients with RA were included in the analysis. MAPLe-RA scale comprised of 21 items, the mean score was 71 (20.28) ranging from 0 to 105. Most items operated in the high expectations part of the items characteristics curves (ICC). Item discrimination varied widely, items with the highest discrimination capacity from the three domains were: pain (physical domain); control of my RA (self-management) and maintaining social role (psycho-social domain); feeling better overall and involvement in treatment decision making (impact of new treatment domain).


CONCLUSIONS
RA patients' expectations of treatment are higher in the physical and psycho-social domains and less so in the impact of new treatment domain.
Academic Department of Rheumatology, Faculty of Life Sciences and Medicine, King's College London, London, UK. fowzia.ibrahim@kcl.ac.uk.|Academic Department of Rheumatology, King's College London, Weston Education Centre, 10, Cutcombe Road, Denmark Hill, London, SE5 9RJ, UK. fowzia.ibrahim@kcl.ac.uk.
Fowzia
F
Ibrahim
Department of Primary Care and Public Health Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK. salma.ayis@kcl.ac.uk.
Salma
S
Ayis
Academic Department of Rheumatology, Faculty of Life Sciences and Medicine, King's College London, London, UK. darija.hofmann@gmail.com.
Darija
D
Hofmann
Department of Health Services & Population Research, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK. diana.rose@kcl.ac.uk.
Diana
D
Rose
Department of Psychology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK. til.wykes@kcl.ac.uk.
Til
T
Wykes
Academic Department of Rheumatology, Faculty of Life Sciences and Medicine, King's College London, London, UK. andrew.cope@kcl.ac.uk.
Andrew
A
Cope
Academic Department of Rheumatology, Faculty of Life Sciences and Medicine, King's College London, London, UK. david.l.scott@kcl.ac.uk.
David L
DL
Scott
Academic Department of Rheumatology, Faculty of Life Sciences and Medicine, King's College London, London, UK. heidi.lempp@kcl.ac.uk.
Heidi
H
Lempp
D000328:Adult; D000368:Aged; D059031:Anticipation, Psychological; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000523:psychology* / Q000628:therapy; D006801:Humans; D008875:Middle Aged; D011594:Psychometrics; D011795:Surveys and Questionnaires / Q000592:standards*; D016896:Treatment Outcome