The Risk Factors Related to Voice Disorder in Teachers: A Systematic Review and Meta-Analysis.

Background and Objectives: Identifying the risk factors of teachers' voice disorders is very important for preventing voice disorders and the recurrence of them. This meta-study identified risk factors associated with teachers' voice disorders through systematic review and meta-analysis and provided basic data for preventing them. Materials and Methods: This study collected literature on the risk factors of teachers' voice disorders using six databases (i.e., CINAHL, EBSCO, PUBMED, SCOPUS, Web of Science, and Springer Link). Search was limited to studies published between 1 January 2000 and 15 October 2018, and a total of 16 publications were selected for the analysis of this study. The quality of selected literature was assessed using the "Standard Quality Assessment Criteria for Evaluating Primary Research Papers from a Variety of Fields". The effect size was analyzed by odds ratio and 95% confidence interval. Results: The results of the quality assessment ranged from 20 to 24 points with six strong studies and ten good studies. The meta-analysis showed that gender, upper airway problems, caffeine consumption, speaking loudly, number of classes per week, and resignation experience due to voice problems were the major risk factors of teachers' voice disorders. On the other hand, age, number of children, drinking, physical activity, smoking, water intake, singing habits, duration of teaching, perception of noise inside the school, number of classes per day, noise assessment inside the classroom, and perception of technology and instruments inside the workplace were not significantly related to voice disorders. Conclusions: Longitudinal studies should be conducted in the future to confirm causality between voice disorders and risk factors based on the results of this study.