Epidemiological differences

Data show that dysphonia has a point prevalence of around 1 per cent among patients seeking treatment, with a female predominance (63.4 per cent).^{Reference Reiter, Hoffmann, Pickhard and Brosch2,Reference Cohen, Kim, Roy, Asche and Courey4} Indian reports of smaller study groups (100–110 patients) showed lower incidence rates of hoarseness (less than 0.5 per cent) and a male predominance (51–89 per cent).^{Reference Baitha, Raizada, Singh, Puttewar and Chaturvedi5–Reference Pal, Kaushal, Nagpure and Agarwal9} The majority of our patient population was male (70 per cent), and the incidence of hoarseness in our study was 12.4 per cent. While the high incidence is probably a result of having a specialised laryngology sub-specialty unit, it also highlights the scope for laryngology in this country. The male predominance, as against the literature in Western, more developed countries, may point towards the perceived lack of importance and limited attention given to non-emergent medical issues in women, regardless of whether the conditions affect quality of life.

Among 80 per cent of Indian patients, the average duration of hoarseness as a presenting complaint has been reported to be around 12 months,^{Reference Baitha, Raizada, Singh, Puttewar and Chaturvedi5} as compared with 1–3 months in more than 60 per cent of patients in Western literature.^{Reference Stachler, Francis, Schwartz, Damask, Digoy and Krouse3,Reference Brouha, Tromp, de Leeuw, Hordijk and Winnubst10} In our study, we found the mean duration of presenting complaints to be 24 months, clearly indicating a delay in seeking medical attention for hoarseness in the Indian subcontinent and a lack of awareness about the need to seek medical attention.

Diagnostic differences

Indian studies report a much lower rate of acute laryngitis (11–23 per cent vs around 40 per cent) and a much higher rate of malignant conditions (8–74 per cent vs around 2–3 per cent),^{Reference Baitha, Raizada, Singh, Puttewar and Chaturvedi5–Reference Pal, Kaushal, Nagpure and Agarwal9} with similar percentages of vocal fold palsy (3–10 per cent) and chronic laryngitis (9–10 per cent), compared with international data.^{Reference Reiter, Hoffmann, Pickhard and Brosch2,Reference Cohen, Kim, Roy, Asche and Courey4} Benign vocal fold lesions reported in Indian literature range from 8 to 60 per cent,^{Reference Baitha, Raizada, Singh, Puttewar and Chaturvedi5–Reference Pal, Kaushal, Nagpure and Agarwal9} compared with 10–31 per cent in Western literature.^{Reference Reiter, Hoffmann, Pickhard and Brosch2,Reference Cohen, Kim, Roy, Asche and Courey4} Our study showed the incidence of malignancy, vocal fold palsy and benign vocal fold lesions to be around 18 per cent, 10.5 per cent and 45 per cent, respectively.

Indian data indicate a 1–5 per cent incidence of laryngeal TB.^{Reference Baitha, Raizada, Singh, Puttewar and Chaturvedi5–Reference Batra, Motwani and Sagar7} Up to 14.5 per cent of head and neck TB cases have been reported to have laryngeal involvement.^{Reference Prasad, Sreedharan, Chakravarthy and Prasad11} While all 32 cases of laryngeal TB reported by Bhat et al.^{Reference Bhat, Latha, Upadhya and Hegde12} had pulmonary involvement, only 20 per cent of laryngeal TB patients reported by Gandhi et al.^{Reference Gandhi, Kulkarni, Mishra and Thekedar13} showed systemic involvement. With 8 out of 10 cases of laryngeal TB (80 per cent) being secondary to pulmonary TB, our findings were similar to those of Lim et al., where the majority had secondary laryngeal TB.^{Reference Lim, Kim, Choi, Kim, Kim and Choi14}

Voice user level data

Voice professionals, such as teachers, broadcasters and musicians, whose professions are reliant on their voice, appear to be most at risk of developing a voice disorder.^{Reference Koufman and Isaacson15–Reference Timmermans, De Bodt, Wuyts, Boudewijns, Clement and Peeters17} Although level 1 voice users are typically well-qualified voice users, others often have insufficient or no voice use and vocal hygiene training, making them more likely to adopt inappropriate voice production techniques. Indian studies have reported that most dysphonic patients can be categorised as a level 4 voice user.^{Reference Batra, Motwani and Sagar7–Reference Pal, Kaushal, Nagpure and Agarwal9} That was also seen in this study, clearly illustrating the need for voice and vocal hygiene education in the general population. In a Belgian study, functional voice disorders (41 per cent), vocal fold nodules or hypertrophy (15 per cent), and reflux, laryngitis or inflammation (11 per cent) were found to be the most common pathologies among professional voice users.^{Reference Van Houtte, Van Lierde, D'Haeseleer and Claeys18}

No studies correlating voice user levels or co-morbidities with pathology were found in the Indian literature search. We observed some interesting, statistically significant associations. First, vocal nodules among both level 1 and 2 voice users suggest that overuse with a lack of adequate rest could be a contributing factor among trained individuals. Second, among level 3 and 4 voice users, vocal polyps were more common, suggesting that sudden phonotrauma causes hoarseness in untrained voice users. Third, vocal cysts were seen more frequently in level 2 voice users.

Co-morbidities, habit-forming substances and dysphonia

Apart from well-proven correlations between tobacco use and laryngeal malignancies,^{Reference Sapkota, Gajalakshmi, Jetly, Roychowdhury, Dikshit and Brennan19–Reference Bobdey, Jain and Balasubramanium22} there are few significant associations between systemic co-morbidities and laryngeal pathologies in South Asian literature. In our patients, tobacco use was significantly associated not only with the presence of laryngeal malignancies, but also with pre-malignant or keratotic lesions, scars and nodules.

Chronic cough has been postulated to be related to an increased prevalence of benign vocal fold lesions.^{Reference Adessa, Xiao, Hull, Bowen, Milstein and Benninger23} The phonotrauma caused by the classical smoker's cough because of the chemical and thermal irritation, or because of underlying pulmonary co-morbidities, leads to increased keratinisation of delicate vocal fold epithelium, which could be the reason for these lesions.^{Reference Adessa, Xiao, Hull, Bowen, Milstein and Benninger23} This could explain why we found not only smoking but also pulmonary co-morbidities to be significantly associated with the presence of keratotic lesions on the vocal folds.

The association of personality types with the formation of nodules and polyps has been extensively discussed in literature.^{Reference El Uali Abeida, Fernández Liesa, Vallés Varela, García Campayo, Rueda Gormedino and Ortiz García24–Reference Yano, Ichimura, Hoshino and Nozue29} In our cohort, the association of hypertension with vocal nodules as well as polyps could be the result of voice abuse and misuse in these individuals who are more subject to stress and tend to become anxious or angry.

Systemic TB was seen in 80 per cent of our patients with laryngeal TB, supporting the data indicating that isolated or primary laryngeal TB is uncommon.^{Reference Lim, Kim, Choi, Kim, Kim and Choi14,Reference Reis, Reis, da Costa, Lucena, Schubach and Oliveira30}

An association between airway stenosis and autoimmune conditions has also been described in the literature (e.g. granulomatosis with polyangiitis, Churg–Strauss syndrome, immunoglobulin G4 disease, and idiopathic subglottic stenosis).^{Reference Aarnæs, Sandvik and Brøndbo31–Reference Kobraei, Song, Mathisen, Deshpande and Mark36} Patients present with hoarseness, cough or breathing difficulty either to the otolaryngologist or to the rheumatologist. After the initial management, the patients often need to be monitored every three to six months, as they tend to relapse.