Pulmonary elastic recoil and diffusing capacity in subjects with intermediate concentrations of alpha-1 antitrypsin

Our plain-English summary of Pulmonary elastic recoil and diffusing capacity in subjects with intermediate concentrations of alpha-1 antitrypsin, by A.W. Musk, P.W. Robertson (Australian and New Zealand Journal of Medicine, 1976).

The study

• Authors: A.W. Musk, P.W. Robertson
• Journal: Australian and New Zealand Journal of Medicine
• Published: 1976;6(4):284-7
• Read it: PubMed · Publisher

Abstract

Serum from 224 males investigated in a prospective study of respiratory disorders in a recently established asbestos industry has been estimated for alpha-1 antitrypsin (AAT) concentration by single radial immunodiffusion. Mean AAT concentration was 213-4 mg/dl). No subject with a markedly reduced level was found. A comprehensive range of lung function tests sensitive to changes anticipated in emphysema at a preclinical stage, included measurements of diffusing capacity and pulmonary elastic recoil. The 26 subjects with AAT concentration less than 150 mg/dl, were regarded as likely to comprise a majority of genotypes MZ and SS, and the 19 subjects with AAT concentration greater than 300 mg/dl were considered to comprise mainly MM. No difference in pulmonary function could be demonstrated between these two groups. Evidence of diminished pulmonary elastic recoil was found in nine smoking subjects whose AAT concentrations were normal and also in one young non-smoking subject with moderately severe asthma, whose AAT concentration was 140 mg/dl. It is concluded that in a male working population, evidence of diminished pulmonary elastic recoil is not a function of AAT concentration.

In plain English

This study measured a blood protein called alpha-1 antitrypsin (AAT) in 224 men from the 238-man workforce of a recently established asbestos mine and mill, as part of a prospective investigation in that industry. All had worked there less than two years, and the authors found no clinical, lung function or X-ray evidence of asbestos-related disease. The article does not name the asbestos fiber type. The aim was to see whether men with intermediate (moderately low) AAT levels showed early, 'preclinical' signs of emphysema. Mean AAT was 213.4 mg/dl, and no one had a grossly reduced level. The 26 men below 150 mg/dl were compared with the 19 above 300 mg/dl and with the men in between. No differences in symptoms or lung function were found, including the lungs' elastic recoil and diffusing capacity, and none of the relevant comparisons was statistically significant. Ten men had reduced elastic recoil. Their mean AAT was 214 mg/dl, and all but one young man with asthma smoked. The authors concluded that reduced elastic recoil in this male working population was not a function of AAT concentration.

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: Cross-sectional comparison of lung function by blood alpha-1 antitrypsin level, carried out within a prospective investigation of a workforce
• Who was studied: 238 males, the entire workforce of a recently established asbestos mine and mill, all employed less than two years and without evidence of asbestos-related disease. AAT was measured in 224 of them. The authors were based in Sydney; the location of the mine is not stated.
• Exposure: The factor studied was serum alpha-1 antitrypsin concentration: below 150 mg/dl, 150-300 mg/dl, and above 300 mg/dl. Smoking was also recorded. Asbestos work was the setting, with employment of less than two years. No fiber type or dose is given.
• Main results:
  • In the 224 men tested, mean AAT was 213.4 mg/dl (range 91-400 mg/dl, SD 55.7 mg/dl). No subject had a grossly reduced concentration.
  • There were no differences in clinical features or pulmonary function tests between the group below 150 mg/dl (26 men), the group above 300 mg/dl (19 men) and the middle group. This included measures of elastic recoil and diffusing capacity.
  • For clinical features, none of the relevant comparisons between AAT groups showed statistically significant differences.
  • Stepwise regression of lung function on age, height and AAT level showed no significant correlation between lung function and AAT concentration.
  • The ten men with diminished elastic recoil had a mean AAT level of 214 mg/dl. Their mean age was 49.2 years, significantly older than the whole group's mean of 33.9 years (P less than 0.001).
  • All of the ten men with diminished elastic recoil except one smoked cigarettes. The exception was a 20-year-old non-smoker with asthma and an AAT of 140 mg/dl. That subject's diffusing capacity was normal, which the authors took to suggest the loss of recoil was more likely secondary to increased airway resistance than to true structural emphysema.
• The authors' conclusion: The authors concluded that, in a male working population, evidence of diminished pulmonary elastic recoil is not a function of AAT concentration. They noted that this does not contradict the association of emphysema with severe AAT deficiency.
• Limitations the authors state:
  • AAT concentration is only an indirect guide to genotype. The relationship between genetic variants and AAT concentration is inconstant, and some subjects with phenotype MZ or SS would be expected in the 150-300 mg/dl group.
  • The low-AAT group may have been younger than groups in which other researchers found reduced elastic recoil. The authors noted, however, that five of the 26 were over 40 and none of these had diminished recoil.
  • The numbers in the low and high AAT groups were small.
  • No corrections for age or height were applied, because mean age, height and weight were comparable across the compared groups.

Topics

Medical terms in this study, explained in our Lexicon: Diffusing Capacity (DLCO), Emphysema.

Related studies

• Single breath diffusing capacity in the industrial setting — B. Make, A. Miller, et al. (1982)
• Association between neutrophil concentration in bronchoalveolar lavage fluid and recent losses in diffusing capacity in men formerly exposed to asbestos — M.R. Cullen, W.W. Merrill (1992)
• Pi*S and Pi*Z alpha 1 antitrypsin polymorphism and the risk for asbestosis in occupational exposure to asbestos — M.J. Lafuente, X. Casterad, et al. (2002)
• Diffusing capacity and forced vital capacity in 5,003 asbestos-exposed workers: relationships to interstitial fibrosis (ILO profusion score) and pleural thickening — A. Miller, R. Warshaw, et al. (2013)
• Biphasic lung diffusing capacity: detection of early asbestos induced changes in lung function — Z. Dujić, J. Tocilj, et al. (1992)
• Relationship of mortality, occupation, and pulmonary diffusing capacity to pleural thickening in the First National Health and Nutrition Examination Survey — D.P. Loomis, G.W. Collman, et al. (1989)

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