Block 3: Occupational Health Management - Section 6: Impairment & Disability

OHM 6.1:  Conceptual overview

Concepts in medical ajudication - impairment and disability

 “Impairment”  LINK TO THE WHO DEFINITION

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).

Grades of impairment  

In order to improve consistency in medical adjudication, and therefore the assessment of  impairment should be graded in a structured and objective manner. 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.  LINK TO MINERS HANDBOOK AND SIMRAC 610 REFS. 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 PERHAPS THIS SHOULD BE A LINKED PAGE OR POPUP

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 COIDA uses the term “disablement”, rather than the more widely used term, “disability”.

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

1 Extent

2 Duration

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 of “permanent” – conditions which have a temporary disability for longer than two years are regarded as “permanent”. This is 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.

Examples illustrating the difference between impairment and disability

An employee with Baker's Asthma who is removed from work and 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 is considered by the COID commissioner to be permanently disabled to some degree (15% disability).

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 the 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” (see above).

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.

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 REFERENCES

WHO INTERNATIONAL CLASSIFICAITON OF IMRPAIRMENT AND DISABILITY

DOCUMENT ON IMPAIRMENT AND DISABILITY

REFS TO IMPAIRMENT CLASSIFICATION SYSTEMS EG AMA OR ATS