Better assessment of physical function: item improvement is neglected but essential

Department of Medicine, Stanford University School of Medicine, 1000 Welch Road, Suite 203, Stanford, CA 94304, USA.
Arthritis research & therapy (Impact Factor: 4.12). 12/2009; 11(6):R191. DOI: 10.1186/ar2890
Source: PubMed

ABSTRACT Physical function is a key component of patient-reported outcome (PRO) assessment in rheumatology. Modern psychometric methods, such as Item Response Theory (IRT) and Computerized Adaptive Testing, can materially improve measurement precision at the item level. We present the qualitative and quantitative item-evaluation process for developing the Patient Reported Outcomes Measurement Information System (PROMIS) Physical Function item bank.
The process was stepwise: we searched extensively to identify extant Physical Function items and then classified and selectively reduced the item pool. We evaluated retained items for content, clarity, relevance and comprehension, reading level, and translation ease by experts and patient surveys, focus groups, and cognitive interviews. We then assessed items by using classic test theory and IRT, used confirmatory factor analyses to estimate item parameters, and graded response modeling for parameter estimation. We retained the 20 Legacy (original) Health Assessment Questionnaire Disability Index (HAQ-DI) and the 10 SF-36's PF-10 items for comparison. Subjects were from rheumatoid arthritis, osteoarthritis, and healthy aging cohorts (n = 1,100) and a national Internet sample of 21,133 subjects.
We identified 1,860 items. After qualitative and quantitative evaluation, 124 newly developed PROMIS items composed the PROMIS item bank, which included revised Legacy items with good fit that met IRT model assumptions. Results showed that the clearest and best-understood items were simple, in the present tense, and straightforward. Basic tasks (like dressing) were more relevant and important versus complex ones (like dancing). Revised HAQ-DI and PF-10 items with five response options had higher item-information content than did comparable original Legacy items with fewer response options. IRT analyses showed that the Physical Function domain satisfied general criteria for unidimensionality with one-, two-, three-, and four-factor models having comparable model fits. Correlations between factors in the test data sets were > 0.90.
Item improvement must underlie attempts to improve outcome assessment. The clear, personally important and relevant, ability-framed items in the PROMIS Physical Function item bank perform well in PRO assessment. They will benefit from further study and application in a wider variety of rheumatic diseases in diverse clinical groups, including those at the extremes of physical functioning, and in different administration modes.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Compared with adults without type 2 diabetes mellitus, those with the disease experience more limitations in their physical functioning (PF). Look AHEAD is a large multicenter trial that examined the effects of an intensive lifestyle intervention (ILI) for weight loss on cardiovascular outcomes compared with diabetes support and education (DSE). Although the current study compared treatment differences between ILI and DSE on PF, the primary goal was to examine whether this effect was moderated by age and history of cardiovascular disease at enrollment.
    The Journals of Gerontology Series A Biological Sciences and Medical Sciences 07/2014; DOI:10.1093/gerona/glu083 · 4.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Stages quantify severity like conventional measures but further specify the activities that people are still able to do without difficulty. To develop Activity Limitation Stages for defining and monitoring groups of adult community-dwelling Medicare beneficiaries. Cross-sectional. Community. There were 14,670 respondents to the 2006 Medicare Current Beneficiary Survey. Stages were empirically derived for the Activities of Daily Living (ADLs) and Instrument Activities of Daily Living (IADLs) by profiling the distribution of performance difficulties as reported by beneficiaries or their proxies. Stage prevalence estimates were determined and associations with demographic and health variables were examined for all community-dwelling Medicare beneficiaries. ADL and IADL stage prevalence. Stages (0-IV) define 5 groups across the separate ADL and IADL domains according to hierarchically organized profiles of retained abilities and difficulties. For example, at ADL-I, people are guaranteed to be able to eat, toilet, dress, and bathe/shower without difficulty, while they experience limitations getting in and out of bed or chairs and difficulties walking. In 2006, an estimated 6.0, 2.9, 2.2, and 0.5 million beneficiaries had mild (ADL-I), moderate (ADL-II), severe (ADL-III), and complete (ADL-IV) difficulties, respectively, with estimates for IADL stages even higher. ADL and IADL stages showed expected associations with age and health-related concepts, supporting construct validity. Stages showed the strongest associations with conditions that impair cognition. Stages as aggregate measures reveal the ADLs and IADLs people are still able to do without difficulty, along with those activities in which they report having difficulty, consequently emphasizing how groups of people with difficulties can still participate in their own lives. Over the coming decades, stages applied to populations served by vertically integrated clinical practices could facilitate large scale planning, with the goal of maximizing personal autonomy among groups of community-dwelling people with disabilities.
    PM&R 05/2014; DOI:10.1016/j.pmrj.2014.05.001 · 1.66 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess disability more efficiently with less burden on the patient, the National Institutes of Health has developed the Patient Reported Outcomes Measurement Information System (PROMIS) Physical Function-an instrument based on item response theory and using computer adaptive testing (CAT). Initially, upper and lower extremity disabilities were not separated and we were curious if the PROMIS Physical Function CAT could measure upper extremity disability and the Quick Disability of Arm, Shoulder and Hand (QuickDASH).
    Clinical Orthopaedics and Related Research 08/2014; 473(1). DOI:10.1007/s11999-014-3840-2 · 2.88 Impact Factor

Full-text (4 Sources)

Available from
May 27, 2014