The Impact of Socioeconomic Status on Voice Outcomes in Patients With Spasmodic Dysphonia Treated With Botulinum Toxin Injections

To determine the impact of socioeconomic status (SES) on voice outcomes for spasmodic dysphonia (SD) patients treated with botulinum toxin injections. This was a prospective cross-sectional study in a tertiary care, academic voice clinic in Canada. Adult SD patients returning to the voice clinic for their botulinum toxin injections were recruited from October 2017 to April 2018. Patients completed a questionnaire on demographic data, the Hollingshead Four-Factor Index for socioeconomic status (validated instrument based on education, occupation, gender, and marital status), and the Voice-Handicap Index 10 (VHI-10) (validated instrument on self-reported vocal handicap). Primary outcome was the association between VHI-10 and Hollingshead Index. Secondary variables were median household income by postal code, duration of disease, gender, age, and professional voice user. Descriptive statistics and multiple linear regression were conducted. One hundred and one patients (age = 62.8 ± 13.7 years, 20.8% male) were recruited with VHI-10 of 22.1 ± 8.1 (out of 40) and Hollingshead Index of 46.3 ± 11.7 (range, 8-66). Median household income was $75？875 ± $16？393, which was above the Canadian average of $70？336. About 91.1% were Caucasian, 54.4% had university degree, 86.1% spoke English, and 43.5% were employed. In multiple linear regression, there was mild to moderate negative correlation (r = ？.292, P = .004) between VHI-10 and Hollingshead Index when controlling for disease duration, age, gender, and professional voice use. SD patients treated with botulinum toxin were mostly affluent, Caucasian, well educated, and English speakers. Lower self-perceived vocal handicap was associated with higher socioeconomic status