Item response theory was used to shorten EORTC QLQ-C30 scales for use in palliative care.
OBJECTIVE
The goal was to develop a shortened version of the EORTC QLQ-C30 for use in palliative care. We wanted to keep as few items as possible in each scale while still being able to compare results with studies using the original scales. We examined the possibilities of shortening the physical functioning, cognitive functioning, fatigue, and nausea and vomiting scales.


METHODS
The shortening was based on 2,366 (physical functioning) and 10,815 (three other scales) observations, respectively. We used item response theory to construct scoring algorithms for predicting scores on the original scales.


RESULTS
Evaluations showed that a three-item physical scale, a two-item fatigue scale, and a one-item nausea or vomiting scale predicted the scores on the original scales with excellent agreement and had measurement abilities similar to the original scales with no loss or only a little loss in power to detect group differences. The results of the cognitive functioning scale indicated problems when predicting scores from a shortened version.


CONCLUSIONS
Given the favorable results for the physical functioning, fatigue, and nausea or vomiting scales we expect that the shortened versions of these scales will be included in the abbreviated version of the EORTC QLQ-C30 for palliative care.
Petersen
Morten Aa
MA
The Research Unit, Department of Palliative Medicine, Bispebjerg Hospital, DK-2400 Copenhagen NV, Denmark. map01@bbh.hosp.dk
Groenvold
Mogens
M
Aaronson
Neil
N
Blazeby
Jane
J
Brandberg
Yvonne
Y
de Graeff
Alexander
A
Fayers
Peter
P
Hammerlid
Eva
E
Sprangers
Mirjam
M
Velikova
Galina
G
Bjorner
Jakob B
JB
D003071:Cognition; D005163:Factor Analysis, Statistical; D005221:Fatigue; D006801:Humans; D007802:Language; D015233:Models, Statistical; D009325:Nausea / Q000503:physiopathology; D009369:Neoplasms / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D010166:Palliative Care / Q000379:methods*; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014839:Vomiting / Q000503:physiopathology