Acoustic analysis in asthmatics and the influence of inhaled corticosteroid therapy

The impact of sustained inhaled corticosteroid (ICS) therapy on the larynx and pharynx was assessed using a prospective, cross-sectional, and investigator-blinded study conducted at the University Hospital Aintree, Liverpool, UK. Forty-six adults recruited from two local general practices and from general ENT clinics at our University hospital were investigated for the study. Patients were allocated to three groups according to ICS use. Laryngeal effects were measured by correlating the results of a vocal performance questionnaire, a respiratory symptom questionnaire, and measurements obtained by computerized speech analysis. Sustained vowels and connected speech were analyzed in normal and asthmatic subjects. Acoustic analysis was correlated with cellular markers of inflammation after biopsy. Regular ICS users had significantly more pharyngeal inflammation and throat discomfort (P<0.0001). Vocal performance was also worse in this group (P<0.0001). They were more likely to have hoarseness, weakness of voice, aphonia, sore throat, throat irritation, and cough (P<0.0001). All these variables were directly related to one another (P<0.0001). Multiple linear regression analysis showed that jitter was a good objective measure of hoarseness (P<0.05). Regular ICS users were significantly more likely to have abnormal jitter, shimmer, and closed-phase quotient scores (P<0.0001). There was no difference between the groups in the observed parameters of inflammation (P>0.01). A higher pharyngitis score did not correlate with any of the histological markers of inflammation (P>0.01). Local side effects are more common in asthmatics that use ICS regularly. Measures of laryngeal function are significantly worse in regular ICS users. However, histological markers and oropharyngeal redness are not reliable measures of inflammation.