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

Objectives: To determine the impact of socioeconomic status (SES) on voice outcomes for spasmodic dysphonia (SD) patients treated with botulinum toxin injections. Methods: 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. Results: 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. Conclusion: 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.