Observer agreement, chest auscultation, and crackles in asbestos-exposed workers

Our plain-English summary of Observer agreement, chest auscultation, and crackles in asbestos-exposed workers, by P. Workum, E.A. DelBono, S.K. Holford, et al (Chest, 1986).

The study

• Authors: P. Workum, E.A. DelBono, S.K. Holford, R.L. Murphy
• Journal: Chest
• Published: 1986;89(1):27-9
• Cited by: 16 articles, 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. 000449).

Abstract

Investigators cite observer variability as a problem in using crackles to diagnose asbestosis. We measured agreement on the presence or absence of crackles noted during auscultation of 64 asbestos-exposed workers in order to clarify this question. There was 89 percent agreement between two observers who simultaneously examined subjects breathing from functional residual capacity (FRC). Kappa (kappa), a statistic accounting for chance agreement, was 0.73. Unanimous agreement between four observers who listened to tape recordings of the breath sounds was 81 percent (kappa = 0.69). When the subjects breathed from residual volume (RV) there was 78 percent (kappa = 0.53) and 67 percent (kappa = 0.60) agreement, respectively. Comparing direct to tape-playback auscultation, there was 90 percent (kappa = 0.77) and 84 percent (kappa = 0.58) intraobserver agreement when the subjects breathed from FRC and 90 percent (kappa = 0.79) and 75 percent (kappa = 0.39) when they breathed from RV. We conclude that observer variability is sufficiently low to allow trained observers to monitor asbestos-exposed workers for crackles directly and during tape-playback auscultation.

In plain English

This study measured how often trained examiners agreed on whether crackles (abnormal crackling lung sounds) were present in 64 asbestos-exposed workers examined during an industrial survey. A lung physician and a trained technician listened at the same time at ten sites at the base of the lungs, using two breathing methods. Tape recordings were later replayed to these two examiners and to two other physicians. Crackles counted as present if heard at two or more sites. Both on-site examiners noted crackles in 15 workers during slow deep breathing and in 14 during rapid deep breathing. During direct listening, the physician and technician agreed on 89 percent of workers (kappa 0.73) with slow deep breathing and 81 percent (kappa 0.57) with rapid deep breathing. Kappa is a measure that allows for chance agreement, where 1.0 means perfect agreement. All four tape listeners agreed on 81 percent of workers with slow deep breathing and 67 percent with rapid deep breathing. The authors concluded that trained observers in a controlled setting can acceptably monitor asbestos-exposed workers for crackles, either directly or from tapes.

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: Observer agreement study. It compared how often examiners agreed with each other (interobserver) and with themselves (direct listening versus tape playback, intraobserver) on the presence or absence of crackles.
• Who was studied: 64 asbestos-exposed workers examined during an industrial survey, aged 20 to 71 years (mean 43). Three had asbestosis by the criteria of Murphy et al. The study came from the Pulmonary Service, Faulkner and Lemuel Shattuck Hospitals, Boston. The article does not give the survey's location or date.
• Exposure: Asbestos exposure lasting from 0 to 41 years (mean 12 years). The article does not name fiber types, products or jobs.
• Main results:
  • Both on-site examiners noted crackles in 15 subjects during tidal-slow deep breathing and in 14 during rapid deep breathing.
  • Direct listening, physician versus technician: 89 percent agreement (kappa 0.73) during tidal-slow deep breathing.
  • Direct listening, physician versus technician: 81 percent agreement (kappa 0.57) during rapid deep breathing.
  • Tape playback, the same two observers: 89 percent agreement (kappa 0.69) for tidal-slow deep breathing and 78 percent (kappa 0.53) for rapid deep breathing.
  • Four tape listeners, majority agreement (three or more agreeing): 92 percent (kappa 0.53) for tidal-slow deep breathing and 84 percent (kappa 0.48) for rapid deep breathing.
  • Four tape listeners, unanimous agreement (all four agreeing): 81 percent (kappa 0.69) for tidal-slow deep breathing and 67 percent (kappa 0.60) for rapid deep breathing.
  • Technician, direct versus tape playback (intraobserver): 90 percent agreement for both breathing methods (kappa 0.77 and 0.79).
  • Physician, direct versus tape playback (intraobserver): 84 percent (kappa 0.58) for tidal-slow deep breathing and 75 percent (kappa 0.39) for rapid deep breathing.
  • The authors described the strength of agreement as moderate or better in all comparisons but one.
• The authors' conclusion: The authors concluded that it is acceptable for trained observers in a controlled setting to monitor asbestos-exposed workers for the presence or absence of crackles, either by direct or by tape-playback listening. They also stated that observations made during tidal-slow deep breathing may be less variable than those made during rapid deep breathing.
• Limitations the authors state:
  • The authors noted that agreement during rapid deep breathing was poorer, probably because breath sounds and stethoscope movement made artifact harder to tell from crackles. They changed the breathing method in later surveys.
  • Among the reasons the authors gave for their agreement being better than in earlier reports: agreement on normality is usually greater than agreement on abnormality, and most subjects did not have crackles.

Topics

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

Related studies

• Agreement between chest radiography and high-resolution computed tomography in diagnosing dust-related interstitial lung fibrosis — R.R. Tiwari (2015)
• Crackles in the early detection of asbestosis — R.L. Murphy, E.A. Gaensler, et al. (1984)
• Radiological and pathological correlations in asbestosis in the Republic of South Africa and the United Kingdom. II. A preliminary study of observer variation in the classification of radiographs of asbestos-exposed workers and the relation of pathology and x-ray appearances — A. Caplan, J.C. Gilson, et al. (1965)
• Diagnosis of asbestosis by a time expanded wave form analysis, auscultation and high resolution computed tomography: a comparative study — N. al Jarad, B. Strickland, et al. (1993)
• Crackles (rales) in the interstitial pulmonary diseases — G.R. Epler, C.B. Carrington, et al. (1978)
• Lung crackle characteristics in patients with asbestosis, asbestos-related pleural disease and left ventricular failure using a time-expanded waveform analysis--a comparative study — N. al Jarad, S.W. Davies, et al. (1994)

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