Clinical Signs

Our plain-English summary of Clinical Signs, by P.G. Harries (1973).

The study

• Author: P.G. Harries
• Published: Biological Effects Of Asbestos (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 8, Pp. 19-24 (1973)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 002391. The article is still under copyright, so we describe it here rather than post it.

In plain English

This book chapter was a review. Its author worked at the Royal Navy Medical Research Unit in Devonport, UK. It described the clinical signs commonly linked to asbestosis: basal crackles (also called rales or crepitations), finger clubbing and cyanosis. It also covered ways of measuring these signs and how recent studies had used them. The chapter did not report a new study group of its own. Citing a shipyard study by other researchers, it reported clubbing in 19.8% of 101 insulators and 5.3% of 94 controls. The chapter reported that further analyses of Devonport Dockyard data linked basal crackles and breathlessness (dyspnoea, Grade 3) to the intensity and duration of exposure, but did not link wheeze or clubbing to exposure. Those analyses estimated that half of men with heavy continuous exposure from age 15 would have crackles by age 39, compared with about age 75 for men with no exposure. The author called cyanosis an unreliable sign and said smoking may play a part in clubbing. The author concluded that basal crackles appeared to be the most useful clinical sign in studies of asbestos disease.

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: Review (book chapter) of clinical signs of asbestosis, methods of objectively measuring them, and their use in recent studies
• Who was studied: No new population was studied. The chapter reviewed published studies of asbestos-exposed workers, mainly insulators and pipe coverers, asbestos textile workers, and shipyard and dockyard workers, often compared with control groups.
• Exposure: Asbestos dust exposure in general. The chapter's main text does not separate fiber types. Exposure was described by job (insulators, pipe coverers, asbestos textile workers, dockyard workers) and, in the Devonport data, by intensity and pattern (heavy continuous, light continuous, light intermittent, none).
• Main results:
  • Further analyses of Devonport Dockyard data found that basal lung crackles and dyspnoea (Grade 3) were associated with intensity and duration of exposure; wheeze and finger clubbing were not.
  • From the Devonport analysis, an estimated 50% of men with heavy continuous exposure from age 15 would have lung crackles by age 39. The estimated ages were 47 for light continuous exposure, 65 for light intermittent exposure, and about 75 for no exposure.
  • Further analysis of the author's earlier data on the hyponychial angle (a measure of finger clubbing) showed no significant relationship to asbestos exposure. The angle increased with age, declined with weight, and differed significantly among smoking groups.
  • In a cited shipyard study (Murphy et al., 1971) comparing 101 pipe coverers (insulators) with 94 controls, clubbing (hyponychial angle greater than 198 degrees) occurred in 19.8% of insulators and 5.3% of controls.
  • The chapter reported that the British Occupational Hygiene Society (1968) used the prevalence of basal lung crackles in asbestos textile workers (16 of 290) to set a hygiene standard: the dose that gives a 1% risk of basal crackles over a working lifetime of exposure.
  • The author described cyanosis as occurring in the later stages of asbestosis and as an unreliable sign.
  • The author described finger clubbing as usually a late and inconstant feature of asbestosis, and stated there is evidence that smoking plays an important part in developing this sign.
• The authors' conclusion: The authors concluded that, of the clinical signs usually linked to asbestos disease, lung crackles were most closely associated with intensity of exposure and with disease severity, and that basal crackles appeared to be the most useful clinical sign in morbidity studies. The author also concluded that cyanosis was of little use in epidemiological studies, and recommended recording at least the presence or absence of lung crackles and finger clubbing.
• Limitations the authors state:
  • The author stated that finger clubbing is subject to a great deal of observer variation, and that clinical signs in general vary considerably between observers.
  • The author stated that further work is needed to assess the usefulness of the hyponychial angle measurement and to establish normal ranges.

Topics

Medical terms in this study, explained in our Lexicon: Clubbing, Cyanosis, Insulator.

Browse return to medical research.