Bronchoalveolar cell differential count and the number of asbestos bodies correlate with survival in patients with asbestosis

Our plain-English summary of Bronchoalveolar cell differential count and the number of asbestos bodies correlate with survival in patients with asbestosis, by E. Keskitalo, L. Varis, R. Bloigu, et al (Occupational and Environmental Medicine, 2019).

The study

• Authors: E. Keskitalo, L. Varis, R. Bloigu, R. Kaarteenaho
• Journal: Occupational and Environmental Medicine
• Published: 2019;76(10):765-771
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To determine cell differential counts and the number of asbestos bodies (ABs) in bronchoalveolar lavage (BAL) fluid obtained from patients with asbestosis, and to correlate the results with their survival.

Methods: The BAL cell differential counts and ABs from 91 patients with asbestosis were determined. The BAL cell differential counts were analysed in relation to smoking status. BAL cell differential counts and the number of ABs were correlated with the patients' survivals.

Results: A neutrophilic cell pattern was observed independently of smoking habits with both Papanicolau (8.4%) and May-Grunwald-Giemsa (6.5%) staining. Smoking and a high number of ABs (>2 AB/mL) were associated with high total cell counts and high macrophage and low lymphocyte differential counts. The median survival of the patients was 131.8 months. Shortened survival was associated with high numbers of ABs (78 vs 165 months; p=0.042) and low lymphocyte (77 vs 179 months; p=0.005), high neutrophil (102 vs 180 months; p=0.016) and high eosinophil (104 vs170 months; p=0.007) differential counts.

Conclusion: A neutrophilic cell pattern was evident in BAL from patients with asbestosis. Smoking and ABs both affected the total cell count and the macrophage and lymphocyte differential counts. Several BAL parameters associated with patient survival, suggesting that BAL cell count analyses could be used in the estimation of the prognosis of patients with asbestosis.

© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.

In plain English

This retrospective study from Oulu University Hospital, Finland, examined bronchoalveolar lavage (BAL) fluid, a sample washed out of the lungs during bronchoscopy, from 91 patients with asbestosis treated between 1996 and 2015. All had high or moderate asbestos exposure, and 86 were men. The fluid showed a raised share of neutrophils, a type of white blood cell, regardless of smoking habits. Smokers, and patients with more than 2 asbestos bodies per millilitre, had higher total cell counts, higher macrophage percentages and lower lymphocyte percentages. Median survival after BAL was 131.8 months. Patients with more than 2 asbestos bodies per millilitre survived for a shorter time than those with 2 or fewer (78.3 vs 165.3 months). Shorter survival was also seen with low lymphocyte, high neutrophil and high eosinophil percentages. In a further analysis, a low lymphocyte percentage remained a statistically significant predictor of higher mortality with both staining methods. A high neutrophil percentage pointed towards higher mortality with both methods, but was statistically significant only with May-Grunwald-Giemsa staining. The authors concluded that BAL cell analysis could help estimate prognosis in asbestosis. They named missing data as the main limitation.

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: Retrospective study of hospital records (cohort of patients with asbestosis who had undergone BAL), with survival analysis
• Who was studied: 91 patients with asbestosis (86 men, 5 women) treated in the respiratory medicine unit of Oulu University Hospital, northern Finland, between 1996 and 2015, who had BAL for diagnostic purposes. 13 were smokers, 55 ex-smokers and 23 non-smokers. Mean age at bronchoscopy was 68.8 years. Diagnoses were verified by the Helsinki criteria.
• Exposure: High or moderate occupational asbestos exposure; fiber types were not reported for the patients. Asbestos bodies were counted in BAL fluid (per mL; 89 patients), split at 2 asbestos bodies per mL. Smoking status was also analysed.
• Main results:
  • Across all patients, BAL neutrophil percentages were raised regardless of smoking: mean 8.36% with Papanicolau staining and 6.52% with May-Grunwald-Giemsa staining.
  • Smokers had a higher total BAL cell count than non-smokers or ex-smokers (p=0.004 and p=0.010). They also had higher macrophage and lower lymphocyte percentages.
  • The median number of asbestos bodies was 1.90 per mL (range 0 to 1850). Patients with more than 2 per mL had a higher total cell count than those with 2 or fewer (282.0 vs 175.0 ×10^6/L; p=0.002). They also had higher macrophage and lower lymphocyte percentages.
  • The number of asbestos bodies did not differ significantly between the smoking groups.
  • Median survival from BAL was 131.8 months overall: 179.6 months in non-smokers, 139.7 in ex-smokers and 75.7 in smokers. The difference by smoking habit was not statistically significant.
  • Patients with 2 or fewer asbestos bodies per mL lived longer than those with more than 2 per mL (165.3 vs 78.3 months; p=0.042).
  • Patients with lymphocytes above 15% lived longer than those at 15% or below: 178.6 vs 77.3 months with Papanicolau staining, and 196.4 vs 103.9 months with May-Grunwald-Giemsa staining.
  • Patients with neutrophils at 3% or below lived longer than those above 3%: 179.6 vs 102.4 months with Papanicolau staining, and 169.6 vs 103.9 months with May-Grunwald-Giemsa staining.
  • With May-Grunwald-Giemsa staining, patients with eosinophils above 1% lived 103.9 months, compared with 169.6 months for those at 1% or below.
  • Macrophage counts showed no correlation with survival.
  • In the multivariate (Cox) analysis with May-Grunwald-Giemsa staining, low lymphocytes (15% or below) had a hazard ratio of 1.99 (95% CI 1.13 to 3.50; p=0.017). High neutrophils (above 3%) had a hazard ratio of 1.69 (95% CI 1.00 to 2.86; p=0.049).
  • In the multivariate analysis with Papanicolau staining, low lymphocytes had a hazard ratio of 1.79 (95% CI 1.02 to 3.13; p=0.043). High neutrophils were also associated with a higher mortality risk (hazard ratio 1.56; 95% CI 0.86 to 2.81; p=0.141), but this was not statistically significant.
  • By the end of the study, 61 of 91 patients (67%) had died. The most common causes of death were asbestosis (43%) and cardiovascular diseases (28%).
• The authors' conclusion: The authors concluded that a neutrophilic cell pattern was evident in BAL of patients with asbestosis, and that smoking and asbestos body numbers both affected total cell, macrophage and lymphocyte counts. They also concluded that several BAL parameters were associated with survival, suggesting BAL cell count analyses could be used in estimating the prognosis of patients with asbestosis.
• Limitations the authors state:
  • The authors stated that, because the study was retrospective, its major limitation was missing information: asbestos body counts were unavailable for two patients and lung function tests for three. They believed this did not significantly affect the validity of the results.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Bronchoalveolar Lavage (BAL), Habit, Macrophage, Median Survival, Prognosis.

Related studies

• Influence of cigarette smoking on bronchoalveolar lavage cellularity in asbestos-induced lung disease — D.A. Schwartz, J.R. Galvin, et al. (1992)
• Brief inhalation of asbestos compromises superoxide production in cells from bronchoalveolar lavage — J.M. Petruska, J. Marsh, et al. (1990)
• Asbestos bodies in bronchoalveolar lavage fluid in relation to occupational history — A. Karjalainen, S. Anttila, et al. (1994)
• Bronchoalveolar lavage cell and lymphocyte phenotype profiles in healthy asbestos-exposed shipyard workers — J.M. Wallace, J.S. Oishi, et al. (1989)
• Distribution of asbestos bodies in the human lung as determined by bronchoalveolar lavage — H. Teschler, N. Konietzko, et al. (1993)
• Asbestos bodies in bronchoalveolar lavage in relation to asbestos bodies and asbestos fibres in lung parenchyma — A. Karjalainen, R. Piipari, et al. (1996)

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