Rasch Analysis and Construct Validity of the Disease Burden Morbidity Assessment in Older Adults

Item Analysis of Functional Measure Indicators in the National Health and Nutrition Examination Survey: A Cross-sectional Study

OBJECTIVE

This study aimed to develop a function, activities, and participation measurement scale using the questions on the National Health and Nutrition Examination Survey (NHANES) by applying item response theory approaches.

DESIGN

This was a cross-sectional study.

PARTICIPANTS

Survey data were collected from 2512 participants within the NHANES.

METHODS

Twenty questions from the NHANES physical functioning section were included. Exploratory and confirmatory factor analyses were conducted to evaluate the factorial structure and model fit of the NHANES instrument. A multidimensional Rasch modeling was used to model the response data after confirming its model fit. To assess validity across subgroups, differential item functioning test was conducted with respect to sex and race using the three-dimensional partial credit model.

RESULTS

Item fit indices indicated a good fit (root-mean-square error of approximation = 0.049, standardized root-mean-square residual = 0.052, Tucker-Lewis index = 0.975). Rasch analysis indicated that "stoop/crouch/kneel," "stand for long periods," and "push/pull large objects" were the three most difficult items, whereas "walk between rooms," "use fork/knife," and "leisure at home" were the easiest. The measure demonstrated good internal consistency overall (Cronbach α = 0.90).

CONCLUSION

The NHANES function, activities, and participation measure demonstrates sufficient evidence of reliability, internal consistency, and validity in noninstitutionalized community-dwelling population.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME.

CME OBJECTIVES

Upon completion of this article, the reader should be able to (1) Recognize the potential benefits of using validated patient-reported functional outcome measures within the publically available National Health and Nutrition Examination Survey (NHANES) data for rehabilitation research; (2) Describe the process of scale development and validation; (3) Identify item difficulty based on the item difficulty distribution; and (4) Identify the applicability of the measure to different population groups based on differential item functioning.

LEVEL

Advanced.

ACCREDITATION

The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s) ™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Assessing patterns and stability of ADL hierarchical scales for functional disability assessment

BACKGROUND AND OBJECTIVES

This study examined the stability over time of activities of daily living (ADL) items in three comparable longitudinal datasets and evaluated ADL loss sequences for older adults in the U.S., South Korea, and Japan.

RESEARCH DESIGN AND METHODS

Data from the U.S. Health and Retirement Study, and its two international sister surveys, were analyzed. Subjects were community-dwelling adults aged 60 and above. For each dataset, Rasch analysis was implemented to determine if the ordering of items remained stable across multiple waves (2006-2014), such that a single ADL hierarchy may be derived from multi-wave data.

RESULTS

Data fitted the Rasch model well. Item calibrations were sufficiently stable across measurement periods in each dataset, reflecting a stable frame of reference. Results were also robust to sample variations. The derived ADL hierarchies based on scaled logit scores revealed that "dressing" and "bathing" were relatively more difficult items for older adults in all study populations.

DISCUSSION AND IMPLICATIONS

Scale stability is essential when exploiting longitudinal data to analyze patterns in ADL disabilities. The consistency in ADL scales across measurement periods supports their use as screening tools and identifying those at risk for transitions in care. Interventions to reduce dependency in bathing and dressing can help improve independent functioning for community-dwelling elderly.

Measuring Activity Limitations Within the National Health and Aging Trends Study (NHATS)

BACKGROUND AND OBJECTIVES

To better understand the disablement process among older adults, improved measures of activity limitations are needed. Traditional population-level measures lack the ability to distinguish precise gradations of activity limitation and are unable to detect degrees of differences over a wide range of ability levels. Therefore, we used contemporary measurement methods to improve upon current methodologies for characterizing activity limitations within the National Health and Aging Trends Study (NHATS) .

RESEARCH DESIGN AND METHODS

We used the NHATS Round 1 cohort to assess the feasibility of constructing an Activity Limitations scale using Rasch item response theory methods. Factor analysis was used to develop the scale from a set of existing items in the NHATS Mobility, Self-Care, and Household Activity domains. Psychometric properties of the scale were evaluated and the scale was used to examine change in activity limitations among the sample from 2011 to 2015.

RESULTS

Results supported an 18-item scale (N = 7,609). Rasch infit and outfit statistics were within acceptable range for all items (Cronbach's alpha = 0.95; sample score reliability = 0.83). From 2011 to 2015, 5.88% older adults demonstrated increase in function, 15% showed decrease in function, and 78% of the sample showed no change (did not exceed ± MDC90).

DISCUSSION AND IMPLICATIONS

Findings demonstrate that a unidimensional, interval scale of activity limitations can be constructed using traditional survey measures nested within the NHATS. Results revealed concerns regarding ceiling effects within the current self-report items of activity limitations suggesting future work is needed to expand the range of ability currently represented in the NHATS Activity Limitation items.

The psychometric validation of the Dutch version of the Rivermead Post-Concussion Symptoms Questionnaire (RPQ) after traumatic brain injury (TBI)

BACKGROUND

Traumatic brain injury (TBI) is one of the most common neurological conditions. It can have wide-ranging physical, cognitive and psychosocial effects. Most people recover within weeks to months after the injury, but a substantial proportion are at risk of developing lasting post-concussion symptoms. The Rivermead Post-Concussion Syndrome Questionnaire (RPQ) is a short validated 16-items self-report instrument to evaluate post-concussive symptoms. The aim of this study was to test psychometrics characteristics of the current Dutch translation of the RPQ.

METHODS

To determine the psychometric characteristics of the Dutch RPQ, 472 consecutive patients six months after they presented with a traumatic brain injury in seven medical centers in the Netherlands (N = 397), and in two in Belgium (Flanders) (N = 75) took part in the study which is part of the large prospective longitudinal observational CENTER-TBI-EU-study. Psychometric properties at six months post TBI, were assessed using exploratory and confirmatory factor analyses. Sensitivity was analyzed by comparing RPQ scores and self-reported recovery status of patients with mild vs. moderate and severe TBI.

FINDINGS

The Dutch version of RPQ proved good, showing excellent psychometric characteristics: high internal consistency (Cronbach's α .93), and good construct validity, being sensitive to self-reported recovery status at six months post TBI. Moreover, data showed a good fit to the three dimensional structure of separate cognitive, emotional and somatic factors (Chi2 = 119; df = 117; p = .4; CFI = .99; RMSEA = .006), reported earlier in the literature.

DISCUSSION

Psychometric characteristics of the Dutch version of RPQ proved excellent to good, and can the instrument therefore be applied for research purposes and in daily clinical practice.