Association of Laryngeal Botulinum Neurotoxin Injection with Work Productivity for Patients with Spasmodic Dysphonia

Importance: A disordered voice can affect an individual across both work and non-work-related life domains. There is insufficient research on the effect of spasmodic dysphonia or its treatment with botulinum neurotoxin (BoNT) injections on work productivity. Objective: To assess whether employed patients with spasmodic dysphonia experience voice-related work productivity impairment before BoNT injection, and had a 10% or greater improvement in productivity 1 month after treatment with BoNT injection. Design, Setting, and Particpants: This prospective case series carried out in 2 laryngology outpatient clinics from November 1, 2015, to August 30, 2018 included a consecutive sample of adult employed patients diagnosed with spasmodic dysphonia. Analysis was conducted between November 1, 2015, to July 31, 2018. Exposures: Treatment with BoNT injection into the intrinsic laryngeal musculature. Main Outcomes and Measures: Eligible participants completed the following validated outcomes instruments immediately before and 1 month after outpatient laryngeal BoNT injection: the Work Productivity and Activity Impairment instrument (WPAI), Voice Handicap Index (VHI), and WorkHoarse. Demographic, comorbidity, and occupational voice use data were also collected at baseline. The changes in outcome measures (primary, WPAI Work Productivity Impairment domain) were tested using a paired 2-tailed t test. Exploratory subgroup analyses were analyzed with multivariable linear regression, adjusting for demographic, comorbidity, and voice use variables. Results: Of the 101 patients enrolled, 75 completed the study. The mean (SD) age of the 75 completing participants was 55.7 (11.8) years and 53 (71%) were women. The participants who completed the study had mean (SD) voice-related work productivity impairment of 43% (27%) at baseline and 22% (23%) at 1 month after BoNT injection (difference, 20% [27%] improvement; 95% CI, 14%-27%; effect size, 0.74). Conclusions and Relevance: This case series study found that employed patients with spasmodic dysphonia reported voice-related work productivity impairment, which improved significantly 1 month after treatment with BoNT injection. The association of spasmodic dysphonia with voice-related work productivity appeared greater in women than men with comparable outcomes with BoNT treatment, but this exploratory sex-associated difference requires independent validation.