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. 2013 Sep;94(9):1661-9.
doi: 10.1016/j.apmr.2013.03.021. Epub 2013 Apr 8.

Development of a computer-adaptive physical function instrument for Social Security Administration disability determination

Pengsheng Ni  1 , Christine M McDonough, Alan M Jette, Kara Bogusz, Elizabeth E Marfeo, Elizabeth K Rasch, Diane E Brandt, Mark Meterko, Stephen M Haley, Leighton Chan
Affiliations

Development of a computer-adaptive physical function instrument for Social Security Administration disability determination

Pengsheng Ni et al. Arch Phys Med Rehabil. 2013 Sep.

Abstract

Objectives: To develop and test an instrument to assess physical function for Social Security Administration (SSA) disability programs, the SSA-Physical Function (SSA-PF) instrument. Item response theory (IRT) analyses were used to (1) create a calibrated item bank for each of the factors identified in prior factor analyses, (2) assess the fit of the items within each scale, (3) develop separate computer-adaptive testing (CAT) instruments for each scale, and (4) conduct initial psychometric testing.

Design: Cross-sectional data collection; IRT analyses; CAT simulation.

Setting: Telephone and Internet survey.

Participants: Two samples: SSA claimants (n=1017) and adults from the U.S. general population (n=999).

Interventions: None.

Main outcome measures: Model fit statistics, correlation, and reliability coefficients.

Results: IRT analyses resulted in 5 unidimensional SSA-PF scales: Changing & Maintaining Body Position, Whole Body Mobility, Upper Body Function, Upper Extremity Fine Motor, and Wheelchair Mobility for a total of 102 items. High CAT accuracy was demonstrated by strong correlations between simulated CAT scores and those from the full item banks. On comparing the simulated CATs with the full item banks, very little loss of reliability or precision was noted, except at the lower and upper ranges of each scale. No difference in response patterns by age or sex was noted. The distributions of claimant scores were shifted to the lower end of each scale compared with those of a sample of U.S. adults.

Conclusions: The SSA-PF instrument contributes important new methodology for measuring the physical function of adults applying to the SSA disability programs. Initial evaluation revealed that the SSA-PF instrument achieved considerable breadth of coverage in each content domain and demonstrated noteworthy psychometric properties.

Keywords: CAT; DIF; Disability evaluation; Disabled persons; Health Status Indicators; IRT; Insurance; PROMIS; Patient-Reported Outcomes Measurement Information System; Psychometrics; Questionnaires; Rehabilitation; SSA; SSA-PF; Social Security Administration; Social Security Administration Physical Function; Statistical model; computer-adaptive testing; differential item functioning; item response theory.

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Figures

Figure 1
Figure 1
Distribution of Physical Function Items/Categories by Content SubDomain
Figure 2
Figure 2
a-e Distribution of Physical Function Person Scores and Reliability of 5 item, 10 item, and Full Item Bank by Subdomain for SSA Claimant (N=1017) and Normative (N=999) Samples a. Changing & Maintaining Body Position Note: Claimant distribution shown in medium grey, Normative in light grey b. Whole Body Mobility Note: Claimant distribution shown in medium grey, Normative in light grey c. Upper Body Function Note: Claimant distribution in medium grey, Normative in light grey d. Upper Extremity Fine Motor Note: Claimant distribution shown in medium grey, Normative in light grey e. Wheelchair Mobility Note: Claimant distribution shown in medium grey, Normative in light grey
Figure 2
Figure 2
a-e Distribution of Physical Function Person Scores and Reliability of 5 item, 10 item, and Full Item Bank by Subdomain for SSA Claimant (N=1017) and Normative (N=999) Samples a. Changing & Maintaining Body Position Note: Claimant distribution shown in medium grey, Normative in light grey b. Whole Body Mobility Note: Claimant distribution shown in medium grey, Normative in light grey c. Upper Body Function Note: Claimant distribution in medium grey, Normative in light grey d. Upper Extremity Fine Motor Note: Claimant distribution shown in medium grey, Normative in light grey e. Wheelchair Mobility Note: Claimant distribution shown in medium grey, Normative in light grey
Figure 2
Figure 2
a-e Distribution of Physical Function Person Scores and Reliability of 5 item, 10 item, and Full Item Bank by Subdomain for SSA Claimant (N=1017) and Normative (N=999) Samples a. Changing & Maintaining Body Position Note: Claimant distribution shown in medium grey, Normative in light grey b. Whole Body Mobility Note: Claimant distribution shown in medium grey, Normative in light grey c. Upper Body Function Note: Claimant distribution in medium grey, Normative in light grey d. Upper Extremity Fine Motor Note: Claimant distribution shown in medium grey, Normative in light grey e. Wheelchair Mobility Note: Claimant distribution shown in medium grey, Normative in light grey
Figure 2
Figure 2
a-e Distribution of Physical Function Person Scores and Reliability of 5 item, 10 item, and Full Item Bank by Subdomain for SSA Claimant (N=1017) and Normative (N=999) Samples a. Changing & Maintaining Body Position Note: Claimant distribution shown in medium grey, Normative in light grey b. Whole Body Mobility Note: Claimant distribution shown in medium grey, Normative in light grey c. Upper Body Function Note: Claimant distribution in medium grey, Normative in light grey d. Upper Extremity Fine Motor Note: Claimant distribution shown in medium grey, Normative in light grey e. Wheelchair Mobility Note: Claimant distribution shown in medium grey, Normative in light grey
Figure 2
Figure 2
a-e Distribution of Physical Function Person Scores and Reliability of 5 item, 10 item, and Full Item Bank by Subdomain for SSA Claimant (N=1017) and Normative (N=999) Samples a. Changing & Maintaining Body Position Note: Claimant distribution shown in medium grey, Normative in light grey b. Whole Body Mobility Note: Claimant distribution shown in medium grey, Normative in light grey c. Upper Body Function Note: Claimant distribution in medium grey, Normative in light grey d. Upper Extremity Fine Motor Note: Claimant distribution shown in medium grey, Normative in light grey e. Wheelchair Mobility Note: Claimant distribution shown in medium grey, Normative in light grey
Figure 3
Figure 3
a and b Claimant Functional Profiles Compared to Age and Sex Specific Normative Scores. a. Profile of a Claimant with an Arm amputation b. Profile of a Claimant with Chronic Low Back Pain
Figure 3
Figure 3
a and b Claimant Functional Profiles Compared to Age and Sex Specific Normative Scores. a. Profile of a Claimant with an Arm amputation b. Profile of a Claimant with Chronic Low Back Pain
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References

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