Varying the item format improved the range of measurement in patient-reported outcome measures assessing physical function

Liegl, Gregor, Gandek, Barbara, Fischer, H. Felix, Bjorner, Jakob B., Ware, John E., Rose, Matthias, Fries, James F. and Nolte, Sandra 2017, Varying the item format improved the range of measurement in patient-reported outcome measures assessing physical function, Arthritis research and therapy, vol. 19, pp. 1-12, doi: 10.1186/s13075-017-1273-5.

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Title Varying the item format improved the range of measurement in patient-reported outcome measures assessing physical function
Author(s) Liegl, Gregor
Gandek, Barbara
Fischer, H. Felix
Bjorner, Jakob B.
Ware, John E.
Rose, Matthias
Fries, James F.
Nolte, SandraORCID iD for Nolte, Sandra
Journal name Arthritis research and therapy
Volume number 19
Article ID 66
Start page 1
End page 12
Total pages 12
Publisher BioMed Central
Place of publication London, Eng.
Publication date 2017-03
ISSN 1478-6362
Keyword(s) Ceiling effects
Item format
Item information
Item-response theory
Measurement range
Patient-reported outcomes
Physical function
Response scale
Disability Evaluation
Middle Aged
Patient Reported Outcome Measures
Rheumatic Diseases
Surveys and Questionnaires
Science & Technology
Life Sciences & Biomedicine
Summary BACKGROUND: Physical function (PF) is a core patient-reported outcome domain in clinical trials in rheumatic diseases. Frequently used PF measures have ceiling effects, leading to large sample size requirements and low sensitivity to change. In most of these instruments, the response category that indicates the highest PF level is the statement that one is able to perform a given physical activity without any limitations or difficulty. This study investigates whether using an item format with an extended response scale, allowing respondents to state that the performance of an activity is easy or very easy, increases the range of precise measurement of self-reported PF. METHODS: Three five-item PF short forms were constructed from the Patient-Reported Outcomes Measurement Information System (PROMIS®) wave 1 data. All forms included the same physical activities but varied in item stem and response scale: format A ("Are you able to …"; "without any difficulty"/"unable to do"); format B ("Does your health now limit you …"; "not at all"/"cannot do"); format C ("How difficult is it for you to …"; "very easy"/"impossible"). Each short-form item was answered by 2217-2835 subjects. We evaluated unidimensionality and estimated a graded response model for the 15 short-form items and remaining 119 items of the PROMIS PF bank to compare item and test information for the short forms along the PF continuum. We then used simulated data for five groups with different PF levels to illustrate differences in scoring precision between the short forms using different item formats. RESULTS: Sufficient unidimensionality of all short-form items and the original PF item bank was supported. Compared to formats A and B, format C increased the range of reliable measurement by about 0.5 standard deviations on the positive side of the PF continuum of the sample, provided more item information, and was more useful in distinguishing known groups with above-average functioning. CONCLUSIONS: Using an item format with an extended response scale is an efficient option to increase the measurement range of self-reported physical function without changing the content of the measure or affecting the latent construct of the instrument.
Language eng
DOI 10.1186/s13075-017-1273-5
Indigenous content off
Field of Research 1103 Clinical Sciences
1107 Immunology
1117 Public Health And Health Services
HERDC Research category C1.1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2017, The Author(s)
Free to Read? Yes
Persistent URL

Document type: Journal Article
Collections: Faculty of Health
School of Health and Social Development
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