Chronic respiratory disease is a major cause of disability worldwide. Evaluation of pulmonary disability for social security or workers’ compensation assessments is an important aspect of clinical care. Examples include the cigarette smoker with severe emphysema who is no longer able to do his or her job, the auto body worker with isocyanate-induced asthma, the retired coal miner with pneumoconiosis, the business executive with severe sleep apnea, or the plumber or ship builder with lung cancer or asbestosis.
An approach to the evaluation of pulmonary disability that largely reflects the recommendations in the American Medical Association Guides to the Evaluation of Permanent Impairment, 6th Edition, will be reviewed here . The routine clinical evaluation and management of the specific conditions noted above are reviewed separately. (See "Disability assessment and determination in the United States" and "Occupational low back pain: Evaluation".)
WHO model of disablement — The World Health Organization (WHO) has developed the International Classification of Functioning, Disability, and Health, known more commonly as the ICF . The ICF is WHO's framework for measuring health and disability at both the individual and population levels. Unlike its predecessor, which was endorsed for field trail purposes only, the ICF was endorsed for use as the international standard to describe and measure health and disability. This model is composed of health and health-related domains that reflect body, individual, and societal perspectives (figure 1) . The components of functioning and disability include body function and structure and also activities and participation. Consideration of environmental factors takes into account that an individual’s functioning and disability occur in a context that may be influenced by their immediate and general environment.
The American Medical Association Guides to the Evaluation of Permanent Impairment, 6th Edition, has embraced this classification system because it incorporates the complex and dynamic interactions between an individual’s medical condition, the environment, and personal factors . Further, it recognizes that the relationships between impairment, activity limitations, and participation are fluid and multidirectional. For instance, an individual may have measurable impairment without significant impact on activity level, either in work or recreation, or conversely they may report major activity limitation without significant demonstrable objective impairment.
Impairment ratings — Physicians are typically asked to provide an impairment rating based upon quantitative objective measurements. This rating is generally submitted to a Social Security Board, Workers' Compensation carrier, or other administrative body that will determine the final degree of disability. Physicians' impairment ratings are usually given heavy weighting in determining the degree of disability. Other socioeconomic factors are given varying degrees of import in the final evaluation.