1Department of Ear, Nose & Throat, Imam Abdulrahman Bin Faisal University, Khobar, Saudi Arabia; 2Department of Ear, Nose & Throat, King Fahd University Hospital, Khobar, Saudi Arabia; 3Department of Ear, Nose & Throat, King Abdullah Medical City, Makkah, Saudi Arabia; 4Royal College of Surgeons in Ireland, Dublin, Ireland *Corresponding Author’s e-mail: dr.rawan212@gmail.com العالقة بني مؤشر اإلعاقة الصوتية ومؤشر أعراض االرجتاع حبث استبياين لعامة الناس واملعلمني غري املشخصني باملرض يف اململكة العربية السعودية روان العنزي، احمد الرحّيم، �شاره بايون�ص، عبدالرحمن الغوينم، حممد البار abstract: Objectives: This study aimed to assess potential associations between self-reported symptoms of laryngo- pharyngeal reflux (LPR) and voice disorders among two undiagnosed cohorts in Saudi Arabia. Methods: This cross- sectional study was conducted from February to April 2017 in Khobar, Saudi Arabia. Validated Arabic versions of the Reflux Symptom Index (RSI) and 10-item Voice Handicap Index (VHI-10) were distributed to 400 teachers at 13 schools and 300 members of the general population attending an ear, nose and throat clinic in Khobar. Scores of >13 and >11 on the RSI and VHI-10 indicated a potential subjective diagnosis of LPR and voice disorders, respectively. Results: A total of 446 individuals took part in the study, including 260 members of the general population (response rate: 86.7%) and 186 teachers (response rate: 46.5%). The mean age was 32.5 years. In total, 62.2% complained of voice and/or reflux problems, with the remaining 37.8% not reporting/unaware of any problems in this regard. Among the teachers, 30.6% and 18.3% had positive RSI and VHI-10 scores, respectively, while 43.1% and 14.6% of the indiv- iduals from the general population had positive RSI and VHI-10 scores, respectively. Overall, VHI-10 scores were significantly associated with RSI scores (P <0.001). Conclusion: A significant association between RSI and VHI-10 scores suggests that there may be an association between LPR and voice disorders. These tools would therefore be a valuable method of monitoring patients; however, they cannot be used to confirm a diagnosis. Thus, more detailed studies are needed to confirm this association using a larger sample size. Keywords: Voice Disorders; Laryngopharyngeal Reflux; Hoarseness; Diagnostic Self Evaluation; School Teachers; Saudi Arabia. امل�شاحبة ال�شوتية والتغريات احلنجري البلعومي الرجتاع اأعرا�ص بني املحتملة العالقة لتقيم الدرا�شة هذه تهدف الهدف: امللخ�ص: البحث هذا عمل مت الطريقة: ال�شعودية. العربية باململكة امل�شخ�شة غري واملدر�شني النا�ص عامة بني من امل�شخ�شني غري للمر�شى لها ال�شتبياين ما بني �شهر فرباير اإىل �شهر اأبريل 2017 يف مدينة اخلرب، باململكة العربية ال�شعودية. ومت توزيع الن�شخة العربية ملوؤ�رس اعرا�ص الرجتاع وموؤ�رس الإعاقة ال�شوتية على 400 مدر�ص يف 13 مدر�شة خمتلفة و 300 ن�شخة مت توزيعها على عامة النا�ص يف عيادات الأنف والأذن واحلنجرة يف مدينة اخلرب يف م�شت�شفى امللك فهد اجلامعي، واإذا كانت النتيجة اأكرث من 13 واأكرث من 11 يف موؤ�رس اعرا�ص الرجتاع وموؤ�رس الإعاقة ال�شوتية على التوايل اأن هناك ت�شخي�شا حمتمال لالرجتاع البلعومي احلنجري والتغريات ال�شوتية امل�شاحبة لها. النتائج: كان اجمايل امل�شاركني يف البحث 446 �شخ�شا �شاركوا معنا، 260 �شخ�شا من عامة النا�ص )معدل ال�شتجابة: %86.7( و 186 مدر�شا )معدل ال�شتجابة: %46.5(. وكان متو�شط العمر 32.5 عاما. املجموع الكلي لأعرا�ص الرجتاع البلعومي احلنجري املبلغ عنها من املري�ص نف�شه وعنده دراية عنها والتغريات ال�شوتية هي %62.2، بينما %37.8 مل يبلغ عن هذه الأعرا�ص لو مل يكن مدركا لوجودها. بني املدر�شني كان هناك %30.6 و %18.3 لديهم موؤ�رس اعرا�ص الرجتاع و موؤ�رس الإعاقة ال�شوتية اإيجابي، على التوايل، بينما كان لدى %43.1 و 14.6% من عامة النا�ص موؤ�رس اعرا�ص الرجتاع و موؤ�رس الإعاقة ال�شوتية اإيجابي، على التوايل. اأثبتت املح�شلة النهائية للبحث اأثبتت اأن هناك عالقة وجود ب�شبب P(. اخلال�صة: >0.001( علمي ب�شكل مرتبطني ال�شوتية الإعاقة موؤ�رس و الرجتاع اعرا�ص موؤ�رس بني وطيدة عالقة وترابط علمي ما بني موؤ�رس اأعرا�ص الرجتاع و موؤ�رس الإعاقة ال�شوتية ن�شتطيع اأن ن�شتنتج اأن هنالك عالقة ما بني الرجتاع البلعومي احلنجري و التغريات ال�شوتية. وبالتايل ميكننا اأن ن�شتخدم هذه املوؤ�رسات يف متابعة املر�شى ونرى مدى حت�شنهم مع العالج، ولكن ل ن�شتطيع ا�شتخدامها كاأداة للت�شخي�ص بحد ذاتها ب�شبب العدد القليل من امل�شاركني يف البحث. لذا نن�شح بعمل درا�شات اأخرى باأعداد اأكرب من امل�شاركني. الكلمات املفتاحية: التغريات ال�شوتية؛ الرجتاع البلعومي احلنجري؛ بحة ال�شوت؛ التقييم الت�شخي�شي الذاتي؛ املعلمون؛ اململكة العربية ال�شعودية. Association Between Voice Handicap Index and Reflux Symptom Index A cross-sectional study of undiagnosed general and teacher cohorts in Saudi Arabia *Rawan Alanazi,1 Ahmed Alrahim,2 Sara Bayounos,3 Abdulrahman Al-Ghuwainem,4 Mohammad H. Al-Bar2 clinical & basic research Sultan Qaboos University Med J, August 2018, Vol. 18, Iss. 3, pp. e350–354, Epub. 19 Dec 18 Submitted 9 Dec 17 Revisions Req. 21 Dec 17, 30 Jan & 19 Apr 18; Revisions Recd. 9 Jan, 30 Mar & 3 May 18 Accepted 10 May 18 Advances in Knowledge - To the best of the authors’ knowledge, no previous study has investigated associations between Reflux Symptom Index (RSI) and 10-item Voice Handicap Index (VHI-10) scores in Saudi Arabia. - This study found a significant association between RSI and VHI-10 scores among two undiagnosed cohorts in Saudi Arabia. doi: 10.18295/squmj.2018.18.03.014 Rawan Alanazi, Ahmed Alrahim, Sara Bayounos, Abdulrahman Al-Ghuwainem and Mohammad H. Al-Bar Clinical and Basic Research | e351 Application to Patient Care - The association between RSI and VHI-10 scores may be useful as a monitoring method in the management of laryngopharyngeal reflux and voice disorders. Laryngopharyngeal reflux (lpr) is an inflammatory reaction which causes laryngitis and pharyngitis due to the backflow of gastric acid into the larynx and pharynx, as opposed to gastro- esophageal reflux which is restricted to the oesophagus.1,2 Although both of these commonly associated diseases are attributed to a loose lower oesophageal sphincter, they are considered different diseases and present with different symptoms.2–5 The most common symptoms of LPR are idiopathic hoarseness, chronic coughing, globus pharyngeus, choking episodes and clearing of the throat.3 Previous research has not documented the crude incidence of LPR in the general population.5 Currently, the Reflux Symptom Index (RSI) is the only tool avail- able to subjectively assess LPR severity.6 The RSI is a self-administered nine-item questionnaire which has been validated and translated into several languages, including Arabic.6,7 Up to 50% of patients with voice disorders also have LPR.8 The Voice Handicap Index (VHI) is among the most widely used tools worldwide for the measurement of the physical, functional and emotional aspects of voice disorders.9 The original 30-item VHI (VHI-30) has also been validated and translated into Arabic.9,10 Franic et al. concluded that the VHI-30 is the best scale to obtain the most relevant clinical information in patients with voice disorders.11 Furthermore, the VHI-30 can be used to predict the occurrence of voice disorders in non- symptomatic high-risk populations, such as smokers and professional voice users.12,13 Other scales to assess voice disorders have been found to correlate with the VHI-30.14,15 In 2004, a simplified 10-item version of the VHI (VHI-10) was developed; this version was found to be less time-consuming, easier to administer in a clinical setting and statistically more robust than the full scale.16 Belafsky et al. administered the RSI and VHI-30 to 25 patients with LPR.6 After a six-month course of proton pump inhibitors (PPIs), both scales were re- administered; their findings indicated that those with greater improvement in RSI scores were 11 times more likely to have corresponding improvements in VHI-30 scores.6 Other research has also indicated clinically significant improvements in both RSI and VHI scores among LPR patients after treatment, thus confirming the usefulness of these indices for the assessment of voice disorders and LPR-related symptoms.17 Wang et al. also noted higher VHI scores among subjects with RSI scores of >13 versus those with scores of <13.18 However, to the best of the authors’ knowledge, no studies have yet been published on this topic in Saudi Arabia. This study therefore aimed to evaluate the potential assoc- iation between self-reported symptoms of voice disorders and LPR using the VHI-10 and RSI, respectively, among two cohorts of undiagnosed members of the general population and teachers in Saudi Arabia. Methods This cross-sectional study was conducted between February and April 2017 in Khobar, Saudi Arabia. An Arabic-language questionnaire was compiled by a trained healthcare professional, consisting of a set of standard- ised data collection sheets to determine sociodemo- graphic and clinical data (i.e. age, gender, occupation, smoking status, health complaints and allergies) as well as validated Arabic versions of the VHI-10 and RSI.7,10 The questionnaires were then randomly distributed to two cohorts. The first cohort consisted of 400 teachers working at 13 public and private schools in Khobar. The second constituted 300 members of the general population attending the Ear, Nose & Throat Clinic of the King Fahd University Hospital (KFUH). Individuals with a history of laryngology surgery, laryngeal cancer and reflux disease or those with a recent history of PPI use were excluded from the study. As per previous research, RSI scores of >13 and VHI-10 scores of >11 were deemed to indicate LPR-related symptoms and voice disorders, respectively.6,19 Data were compiled and analysed using the Statistical Package for the Social Sciences (SPSS), Version 20.0 (IBM Corp., Armonk, New York, USA). Descriptive statistics such as frequencies and percentages were used to summarise data for the VHI and RSI scores among the teacher and general population cohorts. Continuous and categorical variables were analysed using the Student’s t-test and Chi-squared test, respectively. A multiple linear regression analysis was performed to determine significant risk factors for voice disorders among both cohorts. For all statistical analyses, a P value of <0.050 was considered significant. This study was approved by the KFHU institutional review board (#2016-01-147). All participants gave verbal consent after being informed that their participation in the study was entirely voluntary and that all data would be kept confidential. Association Between Voice Handicap Index and Reflux Symptom Index A cross-sectional study of undiagnosed general and teacher cohorts in Saudi Arabia e352 | SQU Medical Journal, August 2018, Volume 18, Issue 3 Results A total of 446 participants took part in the study, including 186 teachers (41.7%; response rate: 46.5%) and 260 members of the general population (58.3%; response rate: 86.7%). In total, there were 222 men (49.8%) and 224 women (50.2%). The mean age was 32.5 years old. The prevalence of smoking was slightly higher among the general population compared to the teachers (11.9% versus 7%). Overall, 112 members of the general popul- ation (43.1%) and 57 teachers (30.6%) had RSI scores of >13, while 38 members of the general population (14.6%) and 34 teachers (18.3%) had VHI-10 scores of >11, respectively [Table 1]. In total, 62.2% of participants complained of voice and/or reflux problems, whereas the remaining 37.8% did not report or were unaware of any issues in this regard. A statistically significant association was found between positive VHI-10 and RSI scores (r = 0.597; P <0.001). A univariate regression analysis indicated that positive RSI and VHI-10 scores were significantly associated among teachers (P <0.001). In the multiple linear regression analysis, smoking was significantly associated with positive VHI-10 scores among members of the general population (β = 2.755; P = 0.027). A subgroup analysis showed that this association was not significant among teachers (β = −2.937; P = 0.259). The adjusted analysis also indicated that positive RSI scores were significantly associated with VHI-10 scores among members of the general population (β = 0.361; P <0.001) [Table 2]. According to a pairwise comparison, there were stat- istically significant differences in mean VHI-10 scores according to smoking status (P <0.001) [Table 3]. Discussion Voice disorders are among the most serious occup- ational hazards for professional voice users. In particular, teachers have a distinctly higher occurrence of voice dis- orders in comparison to individuals in other occup- ations.20,21 Martins et al. showed that the prevalence of dysphonia among teachers varies in different regions (20–80%).22 In a study of teachers in Iowa, USA, almost 40% reported having to cut back on their teaching load due to voice problems.23 In contrast, Roy et al. found Table 1: Prevalence of self-reported symptoms and risk factors of laryngopharyngeal reflux and voice disorders* among members of the general population and teachers in Khobar, Saudi Arabia (N = 446) Symptom/ risk factor n (%)* Teachers (n = 186) Members of the general population (n = 260) VHI-10 >11 34 (18.3) 38 (14.6) <11 152 (81.7) 222 (85.4) RSI >13 57 (30.6) 112 (43.1) <13 129 (69.4) 148 (56.9) Smoking Yes 13 (7) 31 (11.9) No 173 (93) 229 (88.1) Allergies Yes 35 (18.8) 137 (52.7) No 151 (81.2) 123 (47.3) VHI-10 = 10-item Voice Handicap Index; RSI = Reflux Symptom Index. *Self-assessed using validated Arabic versions of the RSI and VHI-10, respectively.7,10 Table 2: Multiple linear regression analysis for risk factors of voice disorders* among members of the general popul- ation and teachers in Khobar, Saudi Arabia (N = 446) Risk factor Unadjusted Adjusted β P value β P value Teachers Smoking status −2.937 0.259 - - Allergies 0.064 0.967 - - RSI score† 0.514 <0.001 - - Members of the general population Smoking status 3.795 0.009 2.755 0.027 Allergies 0.505 0.610 - - RSI score† 0.376 <0.001 0.361 <0.001 RSI = Reflux Symptom Index. *As per scores of >11 on a self-assessed validated Arabic version of the 10- item Voice Handicap Index.10 †Self-assessed using a validated Arabic version of the RSI.7 Table 3: Pairwise comparison of self-reported symptoms of lary- ngopharyngeal reflux and voice disorders* among members of the general population and teachers in Khobar, Saudi Arabia (N = 446) Index Mean score ± SD P value† Teachers (n = 186) Members of the general population (n = 260) Non- smokers (n = 173) Smokers (n = 13) Non- smokers (n = 229) Smokers (n = 31) RSI 11.6 ± 9.6 10.5 ± 8.6 11.5 ± 10.3 14.4 ± 12.5 0.705 VHI-10 7.5 ± 8.1 4.6 ± 5.6 5.0 ± 6.7 8.7 ± 10.9 <0.001 SD = standard deviation; RSI = Reflux Symptom Index; VHI-10 = 10-item Voice Handicap Index. *Self-assessed using validated Arabic versions of the RSI and VHI-10, respectively.7,10 †Using the Kruskal-Wallis test. Rawan Alanazi, Ahmed Alrahim, Sara Bayounos, Abdulrahman Al-Ghuwainem and Mohammad H. Al-Bar Clinical and Basic Research | e353 that nearly 30% of a general adult population in Iowa and Utah, USA, developed a voice disorder during their lifetime, with 7% already suffering from a voice disorder.24 A combination of personal, behavioural and environmental factors may lead to an increased risk of voice disorders in teachers.24,25 Identifying and treating voice disorders at an early stage will improve patient outcomes and quality of life in this population.21,26 The pathophysiology of voice disorders in LPR remains unknown, although a recent systematic review suggested that the disease alters the mucosa at the vibr- atory margin of the vocal folds due to exposure to acid and pepsin.27 These changes may be related to epithelial cell dehiscence, microtrauma, inflammatory infiltrates, Reinke’s space dryness, mucosal drying and epithelial thickening. However, due to the microscopic nature of such changes, many patients with LPR may not be diagnosed using conventional techniques, such as video- laryngostroboscopy.27 A recent study conducted in Saudi Arabia showed that almost 58% of teachers had symptoms of acid reflux.28 In a study of 119 singers, 70 teachers and 111 control subjects, Hočevar-Boltežar et al. observed that subjective reports of LPR was more common among the singers and teachers.29 Another study indicated that LPR were frequent among teachers with dysphonia.30 However, in the current study, there was a similar percentage of subjects with RSI scores of >13 in both the general population and teacher cohorts. According to two studies, LPR was prevalent in 55–79% of patients with hoarseness persisting for more than three months; associations were also observed between RSI and VHI scores.31,32 In comparison to 2,643 volunteers, Wang et al. found that 127 patients with dysphonia had greater LPR-related morbidity based on their RSI, Reflux Finding Score (RFS), VHI and Short Form Health Survey-36 scores, a physical exam- ination and 24-hour ambulatory double pH monitoring.18 In the current study, there was a statistically significant association between RSI and VHI-10 scores in two undiagnosed populations. In addition, there was a strong association with smoking status among members of the general population, although not teachers. This may be because there were fewer smokers among the teachers compared to the general population. Limitations of the present study include the subj- ective self-reported nature of the assessment tools and the lack of objective clinical and endoscopic evaluations of the larynx and head and neck region to confirm the diagnosis of LPR and voice disorders. For example, the RSI does not cover all symptoms of LPR, including common complaints such as earache, ear pressure and throat pain.6 A more accurate diagnostic evaluation of LPR would therefore include the RFS or assessment of the patient’s pH levels.31,33 Furthermore, certain factors—such as allergies, rhinosinusitis, smoking status and laryngeal overuse—can affect both RSI and VHI-10 scores.3,12,17,22,24 The relatively short study period as well as the need for a larger sample size may have also affected the results. The latter issue is particularly concerning given the low response rate among teachers, as previous research has indicated that awareness of vocal hygiene is low in this subset and that 79% of teachers in Saudi Arabia have never consulted an otolaryngology service.34 Other limit- ations include the low response rates and difficulties in the interpretation of certain items. Conclusion There was a significant association between RSI and VHI-10 scores in the current study, suggesting a pot- ential link between LPR and voice disorders. This may constitute a valuable monitoring method in LPR and voice disorder cases; however, these tools are subjective in nature and thus cannot be used to confirm a diagnosis. Therefore, more detailed objective studies are required to confirm the correlation in a larger sample size. c o n f l i c t o f i n t e r e s t The authors declare no conflicts of interest. f u n d i n g No funding was received for this study. a c k n o w l e d g e m e n t s The authors would like to thank the editors at Editage® (Cactus Communications, Mumbai, India) for their help with the English language editing of this article. References 1. Ford CN. Evaluation and management of laryngopharyngeal reflux. JAMA 2005; 294:1534–40. doi: 10.1001/jama.294.12.1534. 2. Vaezi MF. Extraesophageal manifestations of gastroesophageal reflux disease. Clin Cornerstone 2003; 5:32–8. doi: 10.1016/ S1098-3597(03)90097-4. 3. Salihefendic N, Zildzic M, Cabric E. Laryngopharyngeal reflux disease: LPRD. Med Arch 2017; 71:215–18. doi: 10.5455/med arh.2017.71.215-218. 4. Sereg-Bahar M, Jansa R, Hocevar-Boltezar I. Voice disorders and gastroesophageal reflux. Logoped Phoniatr Vocol 2005; 30:120–4. doi: 10.1080/14015430500320182. 5. Joniau S, Bradshaw A, Esterman A, Carney AS. Reflux and laryn- gitis: A systematic review. Otolaryngol Head Neck Surg 2007; 136:686–92. doi: 10.1016/j.otohns.2006.12.004. 6. Belafsky PC, Postma GN, Koufman JA. Validity and reliability of the Reflux Symptom Index (RSI). J Voice 2002; 16:274–7. doi: 10.1016/S0892-1997(02)00097-8. 7. Farahat M, Malki KH, Mesallam TA. Development of the Arabic version of Reflux Symptom Index. J Voice 2012; 26:814.e15–19. doi: 10.1016/j.jvoice.2012.03.010. https://doi.org/10.1001/jama.294.12.1534 https://doi.org/10.1016/S1098-3597%2803%2990097-4 https://doi.org/10.1016/S1098-3597%2803%2990097-4 https://doi.org/10.5455/medarh.2017.71.215-218 https://doi.org/10.5455/medarh.2017.71.215-218 https://doi.org/10.1080/14015430500320182 https://doi.org/10.1016/j.otohns.2006.12.004 https://doi.org/10.1016/S0892-1997%2802%2900097-8 https://doi.org/10.1016/j.jvoice.2012.03.010 Association Between Voice Handicap Index and Reflux Symptom Index A cross-sectional study of undiagnosed general and teacher cohorts in Saudi Arabia e354 | SQU Medical Journal, August 2018, Volume 18, Issue 3 8. Koufman JA, Amin MR, Panetti M. Prevalence of reflux in 113 consecutive patients with laryngeal and voice disorders. Otol- aryngol Head Neck Surg 2000; 123:385–8. doi: 10.1067/mhn. 2000.109935. 9. Jacobson BH, Johnson A, Grywalski C, Silbergleit A, Jacobson G, Benninger MS, et al. The Voice Handicap Index (VHI): Devel- opment and validation. Am J Speech Lang Pathol 1997; 6:66–70. doi: 10.1044/1058-0360.0603.66. 10. Saleem AF, Natour YS. Standardization of the Arabic version of the Voice Handicap Index: An investigation of validity and reliability. Logoped Phoniatr Vocol 2010; 35:183–8. doi: 10.3109/ 14015439.2010.490851. 11. Franic DM, Bramlett RE, Bothe AC. Psychometric evaluation of disease specific quality of life instruments in voice disorders. J Voice 2005; 19:300–15. doi: 10.1016/j.jvoice.2004.03.003. 12. Tafiadis D, Chronopoulos SK, Siafaka V, Drosos K, Kosma EI, Toki EI, et al. Comparison of Voice Handicap Index scores bet- ween female students of speech therapy and other health prof- essions. J Voice 2017; 31:583–8. doi: 10.1016/j.jvoice.2017.01.013. 13. Tafiadis D, Kosma EI, Chronopoulos SK, Papadopoulos A, Drosos K, Siafaka V, et al. Voice Handicap Index and interpretation of the cutoff points using receiver operating characteristic curve as screening for young adult female smokers. J Voice 2018; 32:64–9. doi: 10.1016/j.jvoice.2017.03.009. 14. Murry T, Medrado R, Hogikyan ND, Aviv JE. The relationship between ratings of voice quality and quality of life measures. J Voice 2004; 18:183–92. doi: 10.1016/j.jvoice.2003.11.003. 15. Deary IJ, Wilson JA, Carding PN, MacKenzie K. VoiSS: A patient- derived Voice Symptom Scale. J Psychosom Res 2003; 54:483–9. doi: 10.1016/S0022-3999(02)00469-5. 16. Rosen CA, Lee AS, Osborne J, Zullo T, Murry T. Development and validation of the Voice Handicap Index-10. Laryngoscope 2004; 114:1549–56. doi: 10.1097/00005537-200409000-00009. 17. Park JO, Shim MR, Hwang YS, Cho KJ, Joo YH, Cho JH, et al. Combination of voice therapy and antireflux therapy rapidly recovers voice-related symptoms in laryngopharyngeal reflux patients. Otolaryngol Head Neck Surg 2012; 146:92–7. doi: 10.11 77/0194599811422014. 18. Wang Y, Zhang L, Yu L, Li J, Li J, Zhao Y, et al. [Clinical study of the influence of laryngopharyngeal reflux on quality of life in patients with dysphonia]. Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 2015; 50:973–7. doi: 10.3760/cma.j.issn.1673- 0860.2015.12.002. 19. Arffa RE, Krishna P, Gartner-Schmidt J, Rosen CA. Normative values for the Voice Handicap Index-10. J Voice 2012; 26:462–5. doi: 10.1016/j.jvoice.2011.04.006. 20. Cantor Cutiva LC, Vogel I, Burdorf A. Voice disorders in teachers and their associations with work-related factors: A systematic review. J Commun Disord 2013; 46:143–55. doi: 10.1016/j.jcom dis.2013.01.001. 21. Roy N, Merrill RM, Thibeault S, Parsa RA, Gray SD, Smith EM. Prevalence of voice disorders in teachers and the general popul- ation. J Speech Lang Hear Res 2004; 47:281–93. doi: 10.1044/1092- 4388(2004/023). 22. Martins RH, Pereira ER, Hidalgo CB, Tavares EL. Voice disorders in teachers: A review. J Voice 2014; 28:716–24. doi: 10.1016/j. jvoice.2014.02.008. 23. Smith E, Kirchner HL, Taylor M, Hoffman H, Lemke JH. Voice problems among teachers: Differences by gender and teaching characteristics. J Voice 1998; 12:328–34. doi: 10.1016/S0892-1997 (98)80022-2. 24. Roy N, Merrill RM, Gray SD, Smith EM. Voice disorders in the general population: Prevalence, risk factors, and occupational impact. Laryngoscope 2005; 115:1988–95. doi: 10.1097/01.mlg.00 00179174.32345.41. 25. da Rocha LM, de Lima Bach S, do Amaral PL, Behlau M, de Mattos Souza LD. Risk factors for the incidence of perceived voice disorders in elementary and middle school teachers. J Voice 2017; 31:258.e7–12. doi: 10.1016/j.jvoice.2016.05.018. 26. Lin FC, Chen SH, Chen SC, Wang CT, Kuo YC. Correlation bet- ween acoustic measurements and self-reported voice disorders among female teachers. J Voice 2016; 30:460–5. doi: 10.1016/j. jvoice.2015.05.013. 27. Lechien JR, Saussez S, Harmegnies B, Finck C, Burns JA. Laryn- gopharyngeal reflux and voice disorders: A multifactorial model of etiology and pathophysiology. J Voice 2017; 31:733–52. doi: 10.1016/j.jvoice.2017.03.015. 28. Altwigry AM, Almutairi MS, Ahmed M. Gastroesophageal reflux disease prevalence among school teachers of Saudi Arabia and its impact on their daily life activities. Int J Health Sci (Qassim) 2017; 11:59–64. 29. Hočevar-Boltežar I, Šereg-Bahar M, Kravos A, Mumović G, Mitrović S. Is an occupation with vocal load a risk factor for laryngo- pharyngeal reflux: A prospective, multicentre, multivariate comp- arative study. Clin Otolaryngol 2012; 37:362–8. doi: 10.1111/coa. 12006. 30. Pereira ER, Tavares EL, Martins RH. Voice disorders in teachers: Clinical, videolaryngoscopical, and vocal aspects. J Voice 2015; 29:564–71. doi: 10.1016/j.jvoice.2014.09.019. 31. Katz PO. Ambulatory esophageal and hypopharyngeal pH monitoring in patients with hoarseness. Am J Gastroenterol 1990; 85:38–40. 32. Ozturk O, Oz F, Karakullukcu B, Oghan F, Guclu E, Ada M. Hoarseness and laryngopharyngeal reflux: A cause and effect relationship or coincidence? Eur Arch Otorhinolaryngol 2006; 263:935–9. doi: 10.1007/s00405-006-0097-8. 33. Feng GJ, Zhang LH, Zhao LL, Liu YL. [A pilot study on diag- nosing laryngopharyngeal reflux disease by pH monitoring in laryngopharynx]. Zhonghua Yi Xue Za Zhi 2008; 88:805–8. doi: 10.3321/j.issn:0376-2491.2008.12.004. 34. Hamdan AL, Sibai AM, Srour ZM, Sabra OA, Deeb RA. Voice disorders in teachers: The role of family physicians. Saudi Med J 2007; 28:422–8. https://doi.org/10.1067/mhn.2000.109935 https://doi.org/10.1067/mhn.2000.109935 https://doi.org/10.1044/1058-0360.0603.66 https://doi.org/10.3109/14015439.2010.490851 https://doi.org/10.3109/14015439.2010.490851 https://doi.org/10.1016/j.jvoice.2004.03.003 https://doi.org/10.1016/j.jvoice.2017.01.013 https://doi.org/10.1016/j.jvoice.2017.03.009 https://doi.org/10.1016/j.jvoice.2003.11.003 https://doi.org/10.1016/S0022-3999%2802%2900469-5 https://doi.org/10.1097/00005537-200409000-00009 https://doi.org/10.1177/0194599811422014 https://doi.org/10.1177/0194599811422014 https://doi.org/10.3760/cma.j.issn.1673-0860.2015.12.002 https://doi.org/10.3760/cma.j.issn.1673-0860.2015.12.002 https://doi.org/10.1016/j.jvoice.2011.04.006 https://doi.org/10.1016/j.jcomdis.2013.01.001 https://doi.org/10.1016/j.jcomdis.2013.01.001 https://doi.org/10.1044/1092-4388%282004/023%29 https://doi.org/10.1044/1092-4388%282004/023%29 https://doi.org/10.1016/j.jvoice.2014.02.008 https://doi.org/10.1016/j.jvoice.2014.02.008 https://doi.org/10.1016/S0892-1997%2898%2980022-2 https://doi.org/10.1016/S0892-1997%2898%2980022-2 https://doi.org/10.1097/01.mlg.0000179174.32345.41 https://doi.org/10.1097/01.mlg.0000179174.32345.41 https://doi.org/10.1016/j.jvoice.2016.05.018 https://doi.org/10.1016/j.jvoice.2015.05.013 https://doi.org/10.1016/j.jvoice.2015.05.013 https://doi.org/10.1016/j.jvoice.2017.03.015 https://doi.org/10.1111/coa.12006 https://doi.org/10.1111/coa.12006 https://doi.org/10.1016/j.jvoice.2014.09.019 https://doi.org/10.1007/s00405-006-0097-8 https://doi.org/10.3321/j.issn:0376-2491.2008.12.004