Concepts in medical ajudication - impairment and disability

Having approached medical fitness from the perspective of both exposure risk and capability risk which themselves are somewhat overlapping concepts, there is another important task in medical adjudication.

This relates to the adjudication of the effects of mainly exposure risks on the health status and continued fitness of the worker. Typically this perspective is oriented to work-related impairment and disability and therefore the compensation system in which these concepts are key. Such concepts are also of relevance to early retirement and pensions and boarding arrangements in terms of pension fund provisions.

Of course there can be deterioration in capability from non-work related causes and these are dealt with in the preceding page.

The compensation system is an aspect of social welfare that is geared to providing financial and medical support to those who are injured or become diseases as a result of their work, and is based on a medical judgement with respect to impairment and a legal judgement with respect to the level of disability consequent on the impairment. The impairment must be accepted as work-related.

The World Health Organisation document on the International Classification of Impairment, Disability and Handicap 1980 is currently being revised, and provides relevant definitions.

Impairment:

The term impairment refers to specific deviations from the functional capabilities that would be expected of an average healthy individual. Hence losses of hearing or lung function, or a joint which loses a certain degree of it’s range of motion, are all references to impairments.

These impairments are NOT necessarily disabilities, nor do they render a person automatically "unfit". This depends on the inherent requirements of the job and also the degree of the impairment. The degree to which the impairment becomes a disability is determined by the degree to which the impairment impacts on a variety of issues, such as the ability to earn an income, or to function independently in society (see later in this introduction). The Compensation system operates in terms of established procedures or algorithms which in some cases of occupational disease or injury allow calculation of disability grade from impairment level.

Grades of impairment:

In order to improve consistency in medical adjudication the assessment of impairment should be explicit and objective as far as possible. Various impairment grading systems have been developed around the world for this very reason. An example is the classification of impairment of lung function established by the American Thoracic Society (ATS):

Table 1: Grading of impairment of spirometric lung function (ATS):

Because of the widely different ancestry of people in South Africa "normal" reference values which are often programmed into spirometers will not be appropriate for everyone. Care must therefore be taken to apply appropriate reference values when calculating impairment.

Disability/Disablement:- typically assessment is made by an insurer or the COID Commissioner

The term disability refers to an impairment, which prevents the person from accomplishing certain tasks, or from performing an occupation, thereby impacting on his/her ability to live a normal life, or to earn an income. The calculation of disability is therefore complex and is determined by social, legal, ethical and actuarial considerations. The process of converting impairment to disability is important to the insurance industry, and also in the awarding of damages in legal claims.

The Compensation Commissioner has established guidelines called Instructions that convert impairment to disability. Examples include the tables for loss of hearing and loss of lung function. Interestingly, the COID Act uses the term disablement, rather than the more widely used term, "disability".

When one refers to an employee as being disabled, there are two important descriptors that should be used to define the problem completely. These are:

1. Extent
2. Duration

Examples illustrating the difference between impairment and disability:

An employee with Baker's Asthma who is removed from work and is totally asymptomatic and requires no treatment has zero impairment, yet is considerably disabled in the sense that they may not continue with their habitual work as a baker, and therefore even though unimpaired while out of work such a worker is considered by the COID commissioner to be permanently disabled to some degree (15% disability) in this state while not at work.

Another example of an impairment that does not translate automatically into a disability is that of noise induced hearing loss which is in the higher frequencies predominantly. The formula that is used widely for calculating disability for hearing loss (and, therefore, compensation), places a much higher weighting on the lower frequencies that affect audible speech. Hence impairment can be substantial, with a calculated disability of zero.

A person with a disability is not necessarily unfit for the job which they hold. An example of this is an employee who loses the tip of a finger in an accident (thereby incurring a disability), but who is still perfectly able to continue in his/her job. Hence the disability only renders the person "unfit", if it changes their health status in a way that becomes an "exclusion" in terms of the job’s "inherent requirements".

The difference between impairment and disability is important, and members of the medical evaluation team should only focus on the level of impairment and should try to avoid making inferences regarding the degree of disability, which should be left to the insurer or the COID Commissioner.

Measuring the extent of disability:

Total Disability:

This refers to a disability, which renders the affected person totally unable to perform any form of recognised occupation.

Partial Disability:

This refers to a disability, which interferes specifically with tasks or activities that render the affected person unable to perform certain occupations only.

Duration of disability:

Temporary Disability

This refers to a disability, which affects a person for a discrete and temporary period of time. This may be brief, such as somebody with an injury, with recovery within a few days to weeks, or may be long, such as a person with an illness or injury with a prolonged convalescence (tuberculosis, major injuries).

Permanent Disability

This refers to a disability, which affects the person permanently, or which is untreatable. A typical example of this would be noise-induced hearing loss, spinal injuries, silicosis and asbestosis. To the Compensation Commissioner, permanence also has an administrative definition permanent conditions are those for which there is temporary disability for longer than wo years. This is done in order to prevent protracted case dockets. This is not so in the private insurance industry, which often continues to review even long-term cases every one to two years, in order to ascertain whether or not the affected party has recovered sufficiently to reverse the status of "disabled".

Hence the permutations of these circumstances are as follows:

Temporary partial disability (TPD): this refers to those employees on "light duty" (able to perform alternative, less demanding work). It should be remembered that the practice of making available light duty is not universally practiced in companies - this is something negotiated between the company and the employee.

Temporary total disability (TTD): this is the situation for employees on sick leave or accident leave. They are totally unable to continue in their usual occupation and are sent home (or to hospital) to recover.

Permanent partial disability (PPD): this applies in the same manner as temporary partial disability, but the disability is permanent. That is to say it is not medically treatable.

Permanent total disability (PPD): this applies in the same manner as temporary total disability, but the disability is permanent. That is to say it is not medically treatable.

REFERENCES:

1. WHO ICDIH:International Classification of Impairment, Disability and Handicap, 1980
2. WHO ICDIH: Revision 2003...
3. ATS impairment grading system
4. Handbook of Occupational Health Practice in the South African Mining Industry. R Guild, RI Ehrlich, JR Johnston, MH Ross (Eds). SIMRAC Johannesburg 2001.
5. SIMRAC Health 610: Development of lung function reference tables suitable for use in the South African mining industry.