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Disability Evaluation

Editor: Vanessa M. Piazza Updated: 4/17/2023 4:29:00 PM


According to the CDC, 1 in 4 Americans lives with a disability. This equates to approximately 61 million Americans. Disability, by nature, is a dynamic concept because it involves the relationship between the patient and their injury, physical environment, social atmosphere, economic factors, and religious beliefs. Patients can be affected in functions related to cognition through functions involved with living independently. Although 2 in 5 patients above the age of 65 have a disability, anyone can become disabled at any time in their life. The number of disabled persons is forecasted to be a rapidly growing statistic for several reasons. One reason is the incidence and prevalence of obesity, heart disease, and diabetes. The aforementioned chronic conditions are all risk factors for disability, and as a result of their increase, the incidence of disability will too increase.  Another reason is the increase in life expectancy due to advances in medicine and surgery. More people are surviving what would previously be considered a life-ending ailment. However, a common complication of surviving one of these previously life-ending ailments is residual limb deformity, chronic pain, and impaired mobility, to list a few. These complications can affect the way a person interacts with their environment, therefore, leading to disability. Disability has a continuously evolving definition and legal interpretation, as can be expected by the continuous change in socioeconomics and prevalence of chronic disease.

When discussing disability, it is important to understand the terminology. Simply put, three main words: impairment, disability, and handicap. Impairment is essentially a dysfunction of a body system, such as an organ system or the musculoskeletal system. This can affect how a patient interacts with their home, social, or work environments and can often present as a lack of ability to do something. This is known as a disability. It is important to highlight that not all impairments lead to a disability. Disability can be further categorized into temporary or permanent and partial or total disability. Lastly, the term handicap relates the consequences of a disability for a patient to the community or social environment.  For example, a person with an above-the-knee amputation has difficulty walking long distances and therefore needs to park their vehicle close to the entrance.

As a result of the continuous evolution of disablement, its conceptualization has evolved as well. There are three main paradigms through which disablement can be viewed and interpreted.  The medical paradigm is the original model for disability guidelines. The medical model focuses on the pathology causing the impairment. It seeks to relate organ dysfunction at the simplest level to physical dysfunction. The main problem with this interpretation is that not all organ or system dysfunction has a specific treatment, therapeutic endpoint, or clear-cut disability.  The social paradigm interprets the social and functional barriers associated with certain impairments. What special accommodations are required as a result?

The benefit of this paradigm is that it allows people with a disabling impairment to become empowered and participate in society. The biopsychosocial paradigm is the preferred interpretation for disablement because it is multifaceted. The biological facet incorporates any mental or physical impairment. The psychological facet attempts to interpret the emotional state of the individual and take into account various personal and religious beliefs. The social facet addresses the environmental and infrastructural changes that are required to make the physical environment adaptable for patients with disabilities. The International Classification of Functioning, Disability, and Health (ICF) currently adopts the biopsychosocial paradigm. The ICF is the current scheme for disability created by the World Health Organization, created in 2001. The ICF is a comprehensive outline that incorporates the confounding factors between disease state and impairment or, more simply put, between health and function.[1][2]

As eluded to earlier, there is a large legal component to disablement. The nature of the concept of disability is typically viewed in terms of ability to work and medical care costs. If someone is unable to work or participate in their environment because of a disability, they will need support from government services and legislation. In the United States, the Americans with Disabilities Act (ADA) was passed in 1990. Simply put, this piece of legislation would guarantee Americans with disabilities the equal right to employment opportunities, transportation, and public access. The ADA defines disability as “a physical or mental impairment that substantially limits one or more of the major life activities, a person who has a history or record of such impairment, or a person who is perceived by others as having such an impairment.”  The ADA is a massive piece of legislation, and so this article will only highlight the stipulations relating to employment. For further information on the ADA, please visit[3]

Employment is a major life activity, which in some instances can be life-sustaining. The ADA asks for reasonable accommodation of the employer unless it poses an undue hardship on the employer regarding cost or feasibility. If accommodation is provided, then there is no technical disability associated with a specific impairment in that specific environment. As mentioned before, not every impairment is a disability. For example, a soccer player with a transmetatarsal amputation may have to end his career and thus is disabled. Meanwhile, a computer technician with the same impairment may still be able to work and is therefore not disabled.  Determining the feasibility of reasonable accommodation is up to the employer.

Understanding how impairment will affect a particular individual is important because it will dictate if and how compensation is received. There are several rating systems for both impairment and disability to standardize assessment. However, one common flaw to the system is that the impairment system is often used in lieu of the disability rating system due to the complexity of the process. Multiple compensation systems have their own criteria and definitions. This article will touch on some of the common disability systems before going into the rating schema.

The Social Security Disability Insurance and Supplemental Social Security Income (SSDI and SSI) are two parallel disability insurance systems dictated by federal government legislation.  SSDI is a system that provides benefits to persons who worked in a qualifying job for at least 5-10 years before the onset of the disability and became disabled before the age of 65. SSI, in contrast, provides income to individuals over the age of 65 or those who are blind or disabled. SSI does not require a work history.  The process to apply for SSI starts with the Disability Determination Service. Application for SSI can either be accepted or rejected. If the latter, then it can be resubmitted for reconsideration, and in some instances, there can be a court hearing.[4][5][6]

The industrial revolution inspired the Federal Workers’ Compensation Systems at the turn of the 20th century. As more people were employed by factories and worked in dangerous working conditions, the rate of disability or death resulting from work activities increased. As a result, a monetary compensation system was developed for individuals injured while at work or as a consequence of their employment. Some examples of the Federal Worker’s Compensation programs include Federal Employees’ Act, the Longshore and Harbor Workers’ Compensation Act, Energy Employees Occupational Illness Compensation Act, and The Federal Black Lung Program. Many state programs exist as well, and they all have similar fundamental features, which include: compulsory insurance required for all employers, a no-fault system for injuries or illness acquired at work or through the course of work, wage loss benefits, survivor benefits, compensation for permanent partial or permanent total disability, and many more with various stipulations associated.

The Veterans Benefits Admiration offers disability for individuals and service members previously in full-time active military service and were discharged generally or honorably. There are three broad categories: (1) A service-connected disability, which is a disability that resulted from direct injury or disease while on active duty; (2) Nonservice-connected disability, which is due to an injury not incurred while on active duty; (3) Presumptive service connection which is a category that covers various chronic conditions that manifest within 1 year from discharge from active duty. The amount of compensation is related to the severity of impairment and disability endured and is not subject to state or federal income tax. 

Personal injury claims are insurance provided to individuals who have injury arising out of negligence or intentional act. Personal injury claims typically arise from motor vehicle accidents, slip and fall claims, physical assault claims, and nursing home negligence.[7][8]


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When an individual is applying for disability or filing a personal injury claim, the insurance company or court will ask for a second opinion, also known as an independent medical examination (IME). An IME is a one-time evaluation by a physician not directly involved in the patient's primary treatment. The IME is to answer questions related to the claim and to make diagnoses relevant to the claim. The information obtained in an IME can be used in litigation.  Considering the nature of disability claims, the legal system is often involved. In these instances, the purpose of litigation is to establish causality and relate the current injury to any pre-existing and underlying conditions.  Two main types of causation include medical causation, which is a cause and effect relationship between the disability claim and injury, and legal causation, which is to establish whether or not an injury would have occurred regardless of the alleged act.  Further, when relating an injury to a pre-existing condition, there are two main categories, aggravation, and exacerbation.

Aggravation is defined as a permanent worsening of an existing condition that never returns to baseline. Exacerbation, on the other hand, is only a temporary worsening of the pre-existing condition as it eventually returns to the baseline level of injury or pain. An important concept when discussing disability is Maximum Medical Improvement (MMI). MMI  is the point at which the individual is not expected to make any further functional improvement after sufficient time was given for physiologic healing and all appropriate modalities were exhausted. Pre-existing conditions need to be taken into account when determining MMI.[9][10]

It is important for primary care physicians and all physicians alike to understand that certain workgroups have pre-established rights. For example, prolonged high-stress environments have been shown to be a risk factor for cardiovascular disease. As such, employees of law enforcement or fire departments have a presumed risk for cardiovascular disease, and therefore cardiovascular disease in these populations can be considered work-related. This concept applies to many occupations.

The impairment rating system is complex and can be challenging to understand. However, the system is designed to be easily interpreted by physicians who care for patients with disabilities. The American Medical Association (AMA) produced a document called “AMA Guides to the Evaluation of Permanent Impairment.” This guide was intended to break down the disability rating system further and is frequently updated to reflect current guidelines and medical standards. An impairment rating is defined as “a consensus-derived percentage estimate of a loss of activity reflecting the severity of a given health condition and the degree of associated limitations in terms of activities of daily living.”  Impairment ratings are further broken down to include: qualitative measurements, which are anatomically based and would include impairments such as amputation, joint ankyloses, neuropathies, and various other deformities; quantitative impairments, which are also anatomically based and are measured on a continuous scale that corresponds to the degree of impairment; and diagnosis based impairment (DBI) which is an ordinal ranking system that categorizes impairment by severity (such as a ligament sprain as least severe to a ligament rupture as most severe). The diagnosis-based impairment method can be seemingly complex and difficult to interpret. 

After a diagnosis is made, the diagnosis must be matched with a class on the provided DBI grid (Image 1). The regional body parts are then further subdivided. Once the appropriate grid location is identified, then the grade modifiers are determined to adjust for the level of severity. The grade modifiers include a physical exam (GMPE), functional history (GMFH), and clinical studies (GMCS). The final impairment score is a summation of the grade modifiers.[11][12][13]

Accurate diagnosis is important because each body region is subdivided, as previously mentioned. The spine has four anatomic regions: cervical, thoracic, lumbar, and pelvis. Each region has its own qualitative rating. The upper extremities are broken down into the digits and hand, wrist, elbow, and shoulder. Each region has a separate grid with adjustments that can be made for peripheral nerve injuries, CRPS, or amputation injuries, to list a few. The lower extremity is divided into three anatomic regions: ankle and foot, knee, and hip. Similar to the upper extremity, the lower extremity regions can have adjustments made for various pathologies.  If there are multiple impairments, the impairments must be combined as described in the AMA guide and not simply summated.[14]

Issues of Concern

Disability and return to work. The main goal of disability management is to assist the patient in maintaining functional status or return to functional work status as soon as possible.  Long periods of being out of work can, and have been shown to, contribute to poor physical and mental health. Common medical problems can be easily accommodated at the place of employment.

The American College of Occupational and Environmental Medicine (ACOEM) provides good resources for managing disability patients preparing to return to work. An abbreviated list would include socioeconomic and psychological factors, attitudes and beliefs, health behaviors, clinical measures taken, perception of injury and pain, previous health interventions and diagnostic workups, employer/employee relationship, legal factors, and social environment.  These aforementioned factors are often modifiable and identified early on. For example, there are screening tools that can be used to identify the patients perceived level of injury or pain: The Orebro musculoskeletal pain questionnaire is a self-survey that indicates perceived pain; The Back Disability Risk Questionnaire is a self-reported survey administered during the first two weeks of injury to identify the patients perceived level of injury; The Center of Epidemiologic Studies for Depression scale is a short self-reported questionnaire that identifies depression symptoms and has a good predictive ability for chronic pain patients. Additionally, the employer/employee relationship can be easily improved from the time of employment through the time of injury.

The ACOEM promotes the adoption of an injury-prevention cooperate infrastructure as a majority of work-related injuries are preventable. This infrastructure would include incentivizing healthy lifestyles and return to work programs. Promoting a safer environment and maintaining an interest in the employees’ health and safety enhances the inherent relationship. If an employee is to be injured at work, the ACOEM has shown that early positive contact by the employer has shown to be a strong predictor of earlier return to work.  The Canadian Institute for Work and Health has identified seven principles associated with return to work as seen in.[15][16][17]

If the patient has the opportunity to return to work with modified duties, the patient should do so under the advisement and recommendation of the treating physician. Doing so can be productive and therapeutic. Modified work programs include either decreased or flexible work hours, decreased required shift tasks, and/or workplace modifications to accommodate needs. If the patient has no opportunity to have a temporary or modified job, then the patient may require a temporary total disability claim until MMI is achieved.  The Functional Capacity Evaluation (FCE) is a standardized assessment of an injured individual’s ability to return to a transitional, modified work environment. The FCE may require performance-based tests using job-specific equipment in a simulated or real environment. An additional Job Site Evaluation (JSE) can be obtained by using a specially trained therapist to assess the functions of the job and the physical demands required.[18]

Clinical Significance

Documentation and key components. A thorough history and physical is important at the first evaluation for a disability claim. In addition to noting the precise details of the injury and body parts affected, it is also important to note the functional limitations caused by the impairment. The functional history should include various environments (home, work, social, community, etc.) and different activities (ADLs and iADLs). 

An important standardized scale is the Functional Independence Measure (FIM), which quantifies the patient’s level of independence.  The physical examination should use techniques and maneuvers that are standardized. These may include Manual Muscle Testing (MMT), Range of Motion evaluation with a goniometer, Modified Ashworth Scale for spasticity, and other special tests designed to identify the presence or specific injuries. These tests should be repeated at each visit to show progression or digression of the patient’s progress with therapy.[19][20]

Other Issues

Independent Medical Examiner and litigation. The IME can be asked to provide witness testimony in the court of law. Previously, expert witnesses were exempt from medical malpractice claims and other lawsuits. However, there have been Supreme Court rulings that held expert witnesses liable to traditional malpractice. IMEs must be up to date on current medical-legal terminology and also the current legal standards.

Enhancing Healthcare Team Outcomes

An impairment that causes disability is an injury that extends beyond the physical body part. Patients who become disabled are transitioning into life with a different set of circumstances. The patients are affected personally, socially, professionally, and spiritually. Fortunately, due to progressive movements and increased awareness, the amount of funding and resources available to these patients has increased astronomically.  The recent legislation approved mandates accessibility to all public spaces and appropriate accommodation in workplaces so that these individuals can continue to participate in the community in ways similar to how they had previously.

It is paramount for the physician and all providers participating in the care of a patient with a disability to understand and be familiar with the resources available. The care team should include, but not be limited to, the physician, physical therapist, and/or occupational therapist, and/or speech therapist, psychologist, and case manager. Further, when a patient is on disability from work, it should be the care team's responsibility to return the patient to work as quickly and as safely as possible.

Studies presented by the  American College of Occupational and Environmental Medicine and the Canadia Institue for Work and Health have identified factors that promote a patient's return to work and further discuss the consequences of prolonged time off from work. [Level 5] For these reasons, it is important to have an interprofessional team approach to patients with disabilities.



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