gms | German Medical Science

30. Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie e. V.

Deutsche Gesellschaft für Phoniatrie und Pädaudiologie e. V.

20.09. - 22.09.2013, Bochum

Evidence based medicine of voice disorders: focus on risk factors

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  • corresponding author presenting/speaker P. H. Dejonckere - University of Leuven (KULeuven; Neurosciences), Leuven, Belgium; Federal Institute of Occupational Diseases, Brussels, Belgium

Deutsche Gesellschaft für Phoniatrie und Pädaudiologie. 30. Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie (DGPP). Bochum, 20.-22.09.2013. Düsseldorf: German Medical Science GMS Publishing House; 2013. DocHV8

doi: 10.3205/13dgpp45, urn:nbn:de:0183-13dgpp457

Veröffentlicht: 5. September 2013

© 2013 Dejonckere.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Abstract

Four main categories of risk factors for voice problems have been identified : Voice loading (e.g. the average daily speaking time), general health condition (e.g. gastroesophageal reflux), environmental factors (e.g. dust, dry air, background noise) and psycho-emotional factors (e.g. type D personality, described as the tendency to experience a high joint occurrence of negative affectivity and social inhibition).

A common characteristic of a majority of occupational voice users consists of the ‘intentionality’ of their voice: they need to «operate» on the listener, to reach a goal, to attain an end: this supposes in general an enhanced dynamic range, as well in Fo as in intensity and in speech rate, and an increase of muscular activity in all concerned anatomical structures. Monitoring these voicing conditions should be able to demonstrate the differences in prosody, speech rate, vocal attacks, formantic differentiation etc.

Defining the concept of being “at risk” is an important medico-legal issue. The relative risk of occupational voice users for developing voice disorders, appears – as reported in the literature – curiously low (around 1–2) from a point of view of insurance medicine. However practically all the available publications are based on self-reports and not on objective findings. Furthermore most of the studies cannot make the difference between purely subjective experiences, as vocal fatigue, muscle tension dysphonia (the dysphonia being objectivable by acoustic analysis), and actual visible tissue reactions to phonotrauma, particularly vocal fold nodules. Studies dealing with epidemiological aspects of vocal fold nodules are scarce. In the past the relative failure to investigate voice use and the impact of overuse has resulted in a significant gap in the evidence base of occupational health and safety research. Dosimetry and monitoring should currently fill this gap.

Within occupational voice users, particularly teachers, it is important to identify subgroups with higher relative risks, as e.g. music teachers and teachers of physical education/swimming. A few existing recent articles seem to point out that this increased relative risk is relevant. Laryngoscopic investigations should be included. More data collected from dosimetry and monitoring in various countries and education contexts would make possible meta-analyses, as these strengthen the evidence and convince lawyers.


Text

Categories of risk factors

Four main categories of risk factors for voice problems have been identified [1]

1.
Voice loading: e.g. the average daily speaking time
2.
General health condition: e.g. gastroesophageal reflux
3.
Environmental factors: e.g. dust, dry air, background noise.
4.
Psycho-emotional factors: e.g. Type D personality (described as the tendency to experience a high joint occurrence of negative affectivity and social inhibition).

On the basis of telephonic interviews Roy et al. [2] showed that being a teacher, being a women, having more than sixteen working years in education, being between 40 and 59 years old and a family history of voice problems are all associated with voice problems. These factors might be indicating a bigger chance to develop a voice problem.

The concept of ‘intentionality’

A common characteristic of a majority of occupational voice users consists of the ‘intentionality’ of their voice (although this has not been really investigated from a scientific point of view): they need to « operate » on the listener, to reach a goal, to attain an end: consequently their voice use is a permanent challenge, with the risk to fall short of the mark, and this logically induces some kind of mental stress. Intentionality of voice supposes in general an enhanced dynamic range, as well in Fo as in intensity and in speech rate, simply in order to closier fit the underlying content and meaning. Physiologically it means an increase of muscular activity in all concerned anatomical structures [3]. Furthermore, in some of these categories of voice use, the performer chooses for specific resonance characteristics, as singing or acting formant, or formant tuning.

Monitoring these voicing conditions should be able to demonstrate the differences in prosody, speech rate, vocal attacks, formantic differentiation etc.

Medicolegal issues

Most European contries handle a specific insurance system for occupational diseases, and this raises a double question of medico-legal expertise: on the one hand «Can the worker-patient who claims for compensation be considered as ‘at risk’ for the disease?», and on the other hand «Is the objectivated disease of the claimant related to the occupational activity?».

Defining the concept of being “at risk” is an important medico-legal issue: e.g. according to the Belgian law on occupational diseases “there is an occupational risk when

1.
the exposure to the harmful influence is inherent in the practice of the occupation,
2.
this exposure is distinctly higher than that of the general population,
3.
this exposure is, among the exposed persons, according to generally accepted medical knowledge, the main cause of the disease”.

The relative risk of occupational voice users for developing voice disorders, appears – as reported in the literature – curiously low from a point of view of insurance medicine. The relatively low (around 1–2) relative risk, as reported by Thibeault at al. [4] is contrasting with the percentage of occupational voice users treated in current clinical practice. However practically all the available publications are based on questionnaires, telephonic inquiries, self-reports, and not on objective findings. Furthermore these studies cannot make the difference between purely subjective experiences, as vocal fatigue, muscle tension dysphonia (the dysphonia being objectivable by acoustic analysis), and actual visible tissue reactions to phonotrauma, particularly vocal fold nodules.

Epidemiology, with special focus on patients with phonotraumatic lesions

Studies dealing with epidemiological aspects of vocal fold nodules are scarce [5]. There is an urgent need to focus on occupational voice patients with phonotraumatic lesions, and validly comparing them with controls (e.g. patients with seasonal allergic rhinitis, or occupational voice users without voice problems) from the point of view of occupational history, working conditions, psychological traits and possible biasing factors as gastro-esophageal reflux, smoking and non-occupational voicing habits.

In the past the relative failure to investigate voice use and the impact of overuse has resulted in a significant gap in the evidence base of occupational health and safety research [6]. Dosimetry and monitoring should currently fill this gap.

Within occupational voice users, particularly teachers, it is important to identify subgroups with higher relative risks, as e.g. music teachers and teachers of physical education / swimming. A few existing recent articles [7] seem to point out that this increased relative risk is relevant. Laryngoscopic investigations should be included. More data collected from dosimetry and monitoring in various countries and education contexts would make possible meta-analyses, as these strengthen the evidence and convince lawyers.


References

1.
Kooijman PGC, de Jong FICRS, Thomas G, Huinck W, Donders K, Graamans K, Schutte HK. Risk Factors for Voice Problems in Teachers. Folia Phoniatr Logop. 2006;58:159-74. DOI: 10.1159/000091730 Externer Link
2.
Roy N, Merril RM, Thibeault S, Parsa RA, Gray SD and Smith EM. Prevalence of voice disorders in teachers and the general population. J Speech Lang Hear Res. 2004;47:281-93. DOI: 10.1044/1092-4388(2004/023) Externer Link
3.
Dejonckere PH, ed. Occupational voice: care and cure. The Hague, The Netherlands: Kugler Pub.; 2001.
4.
Thibeault SL, Merrill RM, Roy N, Gray SD, Smith EM. Occupational risk factors associated with voice disorders among teachers. Ann Epidemiol. 2004;14:786-92. DOI: 10.1016/j.annepidem.2004.03.004 Externer Link
5.
Simberg S, Laine A, Sala E, Rönnemaa AM. Prevalence of Voice Disorders Among Future Teachers. J Voice. 2000; 14: 231-5. DOI: 10.1016/S0892-1997(00)80030-2 Externer Link
6.
Hazlett D, Moorhead A, Duffy O. Working Voices An epidemiological study of occupational voice demands and their impact on the call centre industry. Report submitted to the IOSH Research Committee IOSH. The Grange Highfield Drive Wigston Leicestershire; 2011.
7.
Morrow SL, Connor NP. Comparison of voice-use profiles between elementary classroom and music teachers. J Voice. 2011;25:367-72. DOI: 10.1016/j.jvoice.2009.11.006 Externer Link