The U.S. Social Security Administration (SSA) provides disability benefits through the Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) programs. The SSDI program, established in 1956, provides benefits to eligible adults with disabilities who have paid into the Disability Insurance Trust Fund, as well as to their spouses and adult children who are unable to work because of severe long-term disabilities. Enacted in 1972, SSI is a means-tested program based on income and financial assets that provides income assistance from U.S. Treasury general funds to adults aged 65 and older, individuals who are blind, and adults and children with disabilities. As of December 2017, SSDI had approximately 10.4 million beneficiaries and SSI about 7.1 million recipients who were classified as blind or disabled.
To receive SSDI or SSI disability benefits, an individual must meet the statutory definition of disability, which is “the inability to engage in any substantial gainful activity [SGA] by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months.” SSA uses a uses a five-step sequential process to determine whether an adult applicant meets this definition. The agency gathers information, including functional information, from the applicant, relevant health care providers, and third parties about the applicant’s
impairment-related limitations that may affect what he or she can do in a work setting. At step 1, SSA considers applicants’ work activity in the past year. If an applicant is engaging in SGA (determined by earnings), SSA will not proceed with a disability determination. At step 2, SSA determines whether the applicant has a medically determinable physical or mental impairment or a combination of impairments that meets the severity and duration requirements for disability. If so, at step 3 the agency determines whether the applicant’s impairment(s) meets or medically equals one of the listings in the Listing of Impairments, a number of which include functional criteria. For applicants whose impairment(s) do not meet or equal one of the listings, SSA then determines and considers their residual functional capacity (RFC) at steps 4 and 5. RFC is defined as “the most [an applicant] can still do despite [his or her impairment-related] limitations” or restrictions on “a regular and continuing basis,” currently defined as 5 days per week, 8 hours per day, or an equivalent work schedule.
In 2017, SSA asked the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine to convene a committee of relevant experts to provide findings and conclusions regarding the collection of information and assessment of functional abilities relevant to work requirements. The committee’s Statement of Task is presented in Box S-1.
STUDY APPROACH AND SCOPE
The committee conducted an extensive review of the literature pertaining to functional assessment of physical and mental abilities relevant to work requirements, as well as the literature specific to assessment of function and impairment trajectories in individuals with back disorders, cardiac impairments, depression, and traumatic brain injury (TBI). The committee chose to address TBI in addition to the three conditions listed in the Statement of Task (see Box S-1) because of its prevalence and the associated high rates of cognitive impairment and work disability. In addition, the committee held three public meetings and one public teleconference to hear from invited experts in areas pertinent to its charge. The committee also commissioned three papers: on assessment of (1) hearing, (2) speech and language, and (3) vision in the context of work requirements. Collectively, these sources informed the committee’s findings and conclusions.
The information gathered by the committee falls into four overlapping areas. The first is background information on the concepts of disability, function, and functional assessment, along with the types, sources, and quality of functional information; properties of assessment measures; and potential threats to validity in assessments—information that provided context for the committee’s task. Having gathered this information, the committee developed a framework based on the International Classification of
Functioning, Disability and Health (ICF) (see Figure S-1). The framework illustrates a structure and a hierarchy for moving from functional assessment of an individual to his or her capacity to perform work. Some components are influenced more by the person (left of the dotted line), while others are influenced more by work factors (right of the dotted line). These factors can overlap and interact. “Interrupters” are factors associated with the individual’s health condition and its treatment (e.g., medication effects, fluctuations in symptoms) that may limit his or her ability to perform work activities on a sustained basis. In addition, environmental and organizational contextual factors may act as barriers to or facilitators of work performance. In terms of facilitators, modifications to community and work environments permit work participation by many individuals who otherwise would be unable to do so. For example, public transportation, including wheelchair-accessible buses, permits travel to work for many individuals with mobility impairments. Likewise, workplace accommodations and worker adaptation programs offered by employers and employee assistance programs can help workers navigate challenges posed by their conditions and retain employment.
The committee’s framework provides a way of conceptually organizing various sources of information and specific types of tools for assessing function. For example, medical records may provide information about an individual’s particular health condition and its manifestation in body function and structure, while computer adaptive testing may yield information
on the person’s ability to complete goal-based tasks, such as those required for work, that incorporate both mental and physical activities. Collectively, this material demonstrates the theoretical complexity of assessing an individual’s functioning with respect to work. Box S-2 contains definitions for many of the terms used in this discussion.
Second, the committee gathered information on instruments used to assess the integrated effect of individuals’ impairments on general daily life and participation and/or on work-related function, the relationship between instruments used to assess activities of daily living and the physical and mental demands of work, and instruments used to assess limitations in work activity due to health conditions. Also reviewed were a variety of instruments for assessing specific physical and mental functional abilities relevant to work requirements.
Third, the committee explored the spectrum of changes in work-related functional abilities that may occur during the progression of the four selected impairments (back disorders, cardiac impairments, depression, and TBI), as well as the effects of treatment on a person’s ability to perform
work-related functions. The focus on specific impairments illustrated the complexity of assessing function with respect to work.
Fourth, in accordance with its Statement of Task (see Box S-1), the committee reviewed functional assessment processes in selected public and private disability programs that provide monetary benefits.
In addition to findings and conclusions specific to the topics outlined above, the committee formulated five overall conclusions.
Relationship of Functional Abilities to Work Participation
Current models of disability, such as the ICF model, consider disability to involve the effects (limitations) an individual’s health condition places on his or her ability to function and participate fully in society. In keeping with these models, assessment of individuals’ functional abilities relevant to work requirements is an important part of determining whether they are able to meet workplace demands and sustain work performance on a regular and continuing basis.
Numerous validated performance-based and self-report instruments are available to assess physical and mental functions and can be used to inform disability determination. However, assessment of functional abilities does not necessarily address an individual’s capacity to perform tasks required for work participation. Although an individual may be capable of performing each activity separately, he or she may not be able to coordinate and sequence them effectively. In addition, while an individual may be able to perform work tasks successfully during a single assessment, he or she may be unable to perform required work tasks on a sustained or consistent (day-to-day) basis because of one or more underlying physical and/or mental health conditions. For example, an individual may be able to lift a 50-pound box several times during an assessment, but he or she may not be able to do so repeatedly throughout a workday. It also is important to consider that testing is typically administered in a controlled, quiet environment without extraneous noise, social demands, and other factors that typically occur on a job, which, depending on the individual, can adversely affect the ability to perform work tasks.
Factors associated with an individual’s health condition (e.g., treatment demands, side effects) may limit the ability to participate in work on a regular and continuing basis even if the person is able to perform each of the tasks associated with a job. Similarly, environmental factors (e.g., physical [built and natural], social, organizational) may limit an individual’s ability to participate in work on a regular and continuing basis even if the
person is able to perform the relevant work requirements. An individual’s capacity to perform work requirements successfully in one specific work environment does not necessarily indicate the ability to perform the same work in a different setting.
For these reasons, the committee drew the following conclusion:
- Individuals’ assessed functional abilities relevant to work requirements when assessed outside of actual work settings may be insufficient to establish their capacity to perform full-time work on a regular and continuing basis.
Multiple Sources of Work-Related Functional Information
The committee determined that no single source is likely to provide all of the information needed to evaluate an individual’s ability to work. Professionals in multiple disciplines administer and interpret results of assessments of physical and mental function. Convergence of information from multiple sources increases confidence in its validity, making it important to combine and evaluate the consistency of information from different sources (e.g., self-reports, quantitative measures, medical records, consultative examinations) when evaluating an individual’s ability to work. The committee also found that professionals who have responsibility for repeated assessments may render more detailed and accurate evaluations of an individual’s physical and/or mental functioning over time relative to medical specialists who have less frequent interactions with the person and less time per encounter during the same observation period.
Although not without limitations, standardized self-report questionnaires are an important source of information regarding the nature and severity of an applicant’s functional limitations, especially when used in conjunction with other assessments. Qualitative data provided by applicants, family members, and other key sources who are sufficiently familiar with the applicant’s activities, health, and functional status, in combination with a review of medical evidence, complement quantitative information that serves as the basis for disability decisions. The use of measures based on item response theory that can be administered using computer adaptive testing can decrease respondent burden by reducing survey length and administration time while minimizing measurement error. For these reasons, the committee drew the following conclusion:
- The validity of the results of work-related functional assessments is enhanced by a comprehensive approach that includes test results and other information about an individual’s physical and mental
functional abilities from multiple sources, as well as relevant social and environmental factors and the full scope of tasks involved in a job and sustained gainful employment.
Integrated Assessment of Work-Related Functional Ability
The committee determined that numerous validated tests are available for measuring physical and mental functional abilities at the impairment and body or organ system level, although currently no single tool, by itself, can reliably and consistently determine the inability or ability to work. Available instruments, whether based on performance, self-report, or proxy, are useful individually, but their value may be increased when different types of instruments are combined to provide a fuller picture of an individual’s ability to sustain work on a regular and continuing basis, especially when they can be repeated over time. In addition, “integrated” assessment measures that provide information regarding the integrated effect of individuals’ impairments on general daily life and participation are useful for capturing the additive and sometimes multiplicative effects of multiple impairments and comorbid conditions on an individual’s functional ability to meet work requirements. For these reasons, the committee drew the following conclusion:
- Assessments that integrate information about impairments and abilities, including multiple tests of different types, repeated over time, provide the most useful information about work-related function.
Challenges for Assessment of Work-Related Functional Abilities
Assessment of individuals’ functional abilities with respect to work is more complicated than whether and how long a person can sit, stand, walk, or perform specific physical or cognitive activities. An individual’s ability to perform a single work activity needs to be evaluated with respect to the context and practical relevance of his or her ability to perform work tasks effectively and hold a job, including adaptability and work-related personal interactions. The committee’s conceptual framework for assessing work capacity (see Figure S-1) demonstrates the complexity and challenges of using functional measures of individuals’ ability to perform specific activities and tasks, especially instruments that assess only body structures and function or impairments, to make a determination about their capacity to perform work and to sustain full-time work on a regular and continuing basis. In addition, there are a number of threats to the validity of assessments of functional abilities, including testing of maximal versus typical
performance, assessment of episodic activity versus sustained task performance, absence of standardized testing conditions, mixed-motive incentives, compromised test integrity owing to prior use of the test in low-stakes testing applications, and diverse test populations on whom tests may not have been validated. Furthermore, the presence of multiple impairments and comorbidities, including symptoms associated with depression or anxiety, can further impair functioning. For these reasons, the committee drew the following conclusion:
- Numerous challenges complicate accurate assessment of an individual’s ability to work, including the following:
- Measures of physiological, morphological, psychological, or cognitive severity (e.g., laboratory findings, signs, or symptoms of impairments) may not correlate with the severity of functional limitations (i.e., the effect of a condition on an individual’s ability to work or conduct daily life).
- It is simpler to demonstrate inability or limitation to perform a specific activity (e.g., reaching overhead, climbing a ladder) than to demonstrate an individual’s ability to perform the combination of activities required for different occupations.
- Tests of functional abilities often do not measure whether an individual is able to combine functions to perform tasks as needed for work.
- Successful work performance is more than the sum of the specific tasks and skills required, and the overall limitation to successful work for an individual is often more than the sum of single impairments.
- Threats to the validity of assessments of functional abilities include testing of maximal versus typical performance, assessment of episodic activity versus sustained task performance, absence of standardized testing conditions, mixed-motive incentives, compromised test integrity owing to prior use of the test in low-stakes testing applications, and diverse test populations on whom tests may not have been validated.
- Symptoms associated with psychological conditions such as depression and anxiety can affect a person’s ability to manage one or more limitations in a work setting. Therefore, it is necessary to consider them when assessing an individual’s ability to sustain work on a regular and continuing basis because a person’s capacity to work may be overestimated if a psychological comorbidity is present.
Factors Limiting the Quality and Quantity of Information on Functional Ability for an Applicant
The committee determined that functional assessment instruments vary in the degree to which they have been tested or adapted across diverse populations, making it important to consider an instrument’s performance across multiple subgroups. Also, assessment instruments developed for research applications may not account for cultural, linguistic, or literacy factors, such as limited English proficiency or low literacy, which may limit access to such assessments. This may mean that few or no assessments are available that can provide valid and reliable information for these populations.
In addition, health care data relevant to disability determinations, such as the results of specific, expensive tests (e.g., certain cardiovascular tests and psychological test batteries) that are valid and potentially useful, may not be readily available because an individual may be uninsured or underinsured, or the tests may be denied by an insurance plan because they are not deemed medically necessary. Disparities in access to care and consequently poor health outcomes can affect not only the quantity of tests conducted in the context of disability determinations but also the quality of the tests and resulting information. Access to health care professionals, including those with expertise in providing information relevant to disability determination, often is limited by lower socioeconomic status and/or geographical location.
Administrative challenges such as acquisition of an applicant’s clinical records are another factor that may limit available information for disability determinations. Acquiring this information may be difficult for several reasons: providers’ fear of sharing confidential information, the limited capacity of a provider’s organization to gather and transmit records, and high administrative costs for record transfer. For these reasons, the committee drew the following conclusion:
- A number of factors, including age, gender, lower socioeconomic status, race, ethnicity, cultural group, and geographic location, may limit the quality and quantity of functional information available for a disability applicant.
Merriam-Webster. 2019. Performance. https://www.merriam-webster.com/dictionary/performance (accessed April 3, 2019).
O*NET Resource Center. 2019. The O*NET®content model. https://www.onetcenter.org/dl_files/ContentModel_Summary.pdf (accessed April 3, 2019).
WHO (World Health Organization). 2001. International Classification of Functioning, Disability and Health. Geneva, Switzerland: WHO.