Alternative partial respiratory disability rating schemes

Our plain-English summary of Alternative partial respiratory disability rating schemes, by P. Harber (The American Review of Respiratory Disease, 1986).

The study

• Author: P. Harber
• Journal: The American Review of Respiratory Disease
• Published: 1986;134(3):481-7
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001158).

Abstract

There is no standardized method for rating "percentage partial disability" for persons with respiratory impairment of a degree less than totally disabling. Twelve alternative schemes for using results of clinical physiologic testing for "rating" partial respiratory disability are compared by examining their effects on "ratings" of 650 actual asbestos lung disease compensation claimants. The schemes differ by basis (function remaining or function lost), presence of a quantitative "threshold," and "standard" for comparison; some estimate future disability rather than current. Large differences in performance between schemes were noted. The average ratings ranged from 17 to 57 "% Disability." The relative effects on subjects with high versus low degree of physiologic impairment differed between rating schemes. The ratings were different for subjects with different patterns of physiologic abnormality.

In plain English

This article compared 12 ways of turning lung function test results into a "percentage partial disability" rating. The schemes differed in whether they were based on lung function remaining or function lost, and in whether they used a threshold. The author applied them to test results from 650 people evaluated at UCLA from 1980 to 1984 for possible asbestos-associated lung disease. One scheme, based on exercise testing, could rate only people who had exercise tests; data from 176 such tests were available. Leaving aside the American Thoracic Society scheme, mean ratings ranged from 17 to 57%, and the share of people rated 0% ranged from 0 to 50%. Each other scheme's ratings differed significantly from those of the American Medical Association Guides, used for comparison. The greatest differences appeared when disability was mild. People with an obstructive pattern of lung abnormality had the highest relative ratings, which the author thought probably reflected the population studied. None of the schemes attributed disability to asbestos specifically. The author concluded that the methods can lead to strikingly different estimates, so careful attention to the choice of method is necessary.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Methodological comparison of 12 partial respiratory disability rating schemes, applied to existing clinical lung function and exercise test data. The schemes differed by basis (function remaining or function lost) and by whether they used a threshold.
• Who was studied: 650 subjects evaluated at UCLA between 1980 and 1984 for possible asbestos-associated lung disease; most had filed compensation claims. The subjects included 3 females; 46% were white, 44% black and 9% other races; mean age 54 years. Exercise test data were available for 176 subjects. Only those subjects could be rated by Scheme 1 (Jobs Unavailable).
• Exposure: Subjects were evaluated between 1980 and 1984 for possible asbestos-associated lung disease. No fiber types, jobs or doses are reported; the comparison is between rating methods.
• Main results:
  • Excluding the ATS criteria, the percentage of subjects with 0% ratings varied from 0 to 50% across schemes. The mean ratings varied from 17 to 57%.
  • Scheme 1 (Jobs Unavailable) rated only subjects who had exercise tests; data from 176 exercise tests were available for the analysis.
  • In paired t tests, each scheme's ratings were significantly different from those of Scheme 5 (AMA Guides), the comparison scheme.
  • The greatest disparities between schemes were seen when mild disability was present (for example, ratings under 20%).
  • The AMA Guides method gave results quite similar to the '% Lower Limit of Normal' scheme.
  • Among the physiologic subgroups, subjects in Group 2 (obstructive) had the highest relative ratings.
  • None of the schemes attributed disability to specific causes such as the worker's asbestos exposure.
• The authors' conclusion: The author concluded that the available methods can lead to strikingly different estimates, so careful attention to the choice of method is necessary.
• Limitations the authors state:
  • The author stated that no amount of statistical manipulation, such as that in this report, can guarantee a fair rating scheme without accurate empiric data on the requirements of work and other life activities.
  • The job requirement data used for the 'Jobs Unavailable' scheme were published 27 years earlier and may not reflect the current work force.
  • Using 95% confidence intervals to define normality is, in the author's words, quite arbitrary.
  • Schemes based on function lost need the worker's lung function before injury. This is rarely available and was estimated from prediction equations.
  • The author suggested that the higher ratings in obstructive subjects probably reflect the nature of the population studied rather than inherent biases in the rating systems.
  • The similarity between Schemes 1 and 9 would need to be confirmed in other populations.

Related studies

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• Childhood exposure to Libby amphibole asbestos and respiratory health in young adults — P.H. Ryan, C.H. Rice, et al. (2017)
• Compensation scheme for complementary and alternative medicine use in asbestos-related diseases in New South Wales, Australia — C. Oak, H.J. Choi, et al. (2012)
• Respiratory toxicity of multi-wall carbon nanotubes — J. Muller, F. Huaux, et al. (2005)
• Occupational respiratory disease in mining — M.H. Ross, J. Murray (2004)
• Work-related respiratory disease in the United Kingdom, 1989-1992: report on the SWORD project — S.K. Meredith, J.C. McDonald (1994)

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