Factor analysis of clinical data from asbestos workers: implications for diagnosis and screening

Our plain-English summary of Factor analysis of clinical data from asbestos workers: implications for diagnosis and screening, by P. Harber, M. Lew, D.P. Tashkin, et al (British Journal of Industrial Medicine, 1987).

The study

• Authors: P. Harber, M. Lew, D.P. Tashkin, M. Simmons
• Journal: British Journal of Industrial Medicine
• Published: 1987;44(11):780-4
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000318).

Abstract

Clinical data from 624 asbestos exposed workers were analysed by factor analysis. Fifteen clinical variables were found to reflect several underlying factors: "obstruction," "interstitial disorder," "x ray change," "air tapping," and "age/exposure." Scoring individual subjects along these axes can facilitate identifying early cases and avoiding false diagnosis. The analysis suggests that screening should be multimodal and that radiographic abnormality need not imply physiological impairment.

In plain English

The authors analysed clinical records of 624 asbestos-exposed men, mostly shipyard workers. The men were examined at the UCLA Medical Center between 1980 and 1984 after possible abnormalities in a shipyard screening programme or after filing a compensation claim. Their mean age was 56 years and exposure lasted one to 51 years. The authors described exposures as mostly moderate to heavy, though no industrial hygiene measurements were available. Using factor analysis, a statistical method, the authors examined how 15 clinical measures grouped together. These included breathing tests, chest x ray readings, breathlessness, age, exposure and smoking. In the whole group the measures fell into five underlying factors, which the authors named obstruction, interstitial, air trapping, x ray and age/exposure. X ray findings grouped separately from breathing-test measures. In current smokers and non-smokers analysed separately, pleural changes grouped with age and exposure. The authors concluded that screening should be multimodal and that x ray abnormality need not imply impaired lung function. They called their conclusions tentative and said the population may not be typical of workers currently exposed.

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: Statistical analysis (factor analysis) of existing clinical examination data from asbestos-exposed workers, with separate analyses for current smokers and non-smokers
• Who was studied: 624 asbestos-exposed men, described as mostly shipyard workers, examined at the UCLA Medical Center (Los Angeles) between 1980 and 1984. They were referred after possible abnormalities in a shipyard screening programme or after filing a compensation claim. The Results give their mean age as 56 years. The Methods print it with scanning damage as '55 9 ± 10-4', apparently 55.9 with SD 10.4. 46.5% were white and 43.3% black (Table 1 prints 43.8%). Subgroups were 166 current smokers and 146 non-smokers.
• Exposure: Asbestos exposure, mostly in shipyards. Fiber type is not stated. Duration ranged from one to 51 years; the Results give the mean as 21 years. Exposures were described as mostly moderate to heavy, with no industrial hygiene data.
• Main results:
  • In the whole group of 624, the 15 clinical variables reflected five underlying factors, which the authors named obstruction, interstitial disorder, x ray change, air trapping and age/exposure.
  • Chest x ray findings, particularly in the analysis of all subjects, were related to factors separate from those most associated with the breathing (physiological) test results.
  • In the current smoker and non-smoker subgroups, but not in the all-subjects analysis, age, exposure and pleural changes were related to a common factor.
  • In the current smokers group, air trapping did not appear as a separate, independent factor.
  • Spirometry results suggestive of restrictive lung disease were present in 4.4% of the study population.
  • Lung function in current smokers was worse than in non-smokers.
  • The authors provided formulas by which each subject's data could be summarised as scores on 4 to 5 indices representing different processes.
• The authors' conclusion: The authors concluded that their analysis suggests screening should use several types of tests, and that an abnormality on chest x ray need not imply physiological impairment.
• Limitations the authors state:
  • The authors said their conclusions must be considered tentative. They noted that factor analysis is subject to probabilistic variation and may be affected by the choice of analytical technique.
  • The studied population may not be typical of workers currently exposed to asbestos. Their exposures were heavy and long, and most were older.
  • Many of the chest x rays were not read using the ILO classification system.
  • Specific industrial hygiene (exposure measurement) data were not available.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Interstitial.

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