Has Research Failed to Identify Risk Factors for Voice Disorders? A Systematic Review of Evidence in Teachers.

Abstract

Objectives: Dysphonia poses a major occupational risk for teachers. Despite the growing interest in this area of research, there is still no comprehensive understanding of the risk factors.

Methods: This systematic review examined risk factors for voice disorders among K-12 teachers. It analyzed 111 publications from 33 countries that were published between January 2013 and February 2024. The novel SIMU Matrix was used to categorize the factors as social/individual or modifiable/unmodifiable.

Results: Based on the proportion of studies that reported significant associations, 10 factors demonstrated the strongest association with voice disorders. Unmodifiable social factors included elementary teaching (14/29 studies). Unmodifiable individual factors included gender (21/40 studies), age (12/41 studies), and professional experience (12/34 studies). Notably, a paradox regarding gender emerged: women reported more voice problems through self-assessments yet demonstrated better vocal health through laryngological and acoustic examinations. Modifiable social factors included workload (13/31 studies) and noise exposure (14/21 studies). Modifiable individual factors included ENT symptoms (17/23 studies), chronic stress (12/15 studies), loud speaking (11/14 studies), and frequency of sick leave (11/13 studies). Assessment methods varied considerably, with a concerning reliance on single-item measurements, despite the fact that voice disorders are recognized as multidimensional conditions.

Conclusions: This review identified numerous factors associated with voice disorders in teachers, demonstrating the complexity of this issue. Some of these factors are modifiable, offering concrete intervention opportunities regarding workplace conditions and health behaviors. However, despite extensive research investigating an even broader range of potential influences, there is still no consensus on key risk factors. This may reflect methodological limitations, including heterogeneous assessments, inadequate statistical corrections, and predominantly cross-sectional designs. Future research requires standardized assessment approaches, appropriate statistical rigor, and longitudinal designs to establish causal relationships and inform evidence-based prevention strategies.