Effectiveness of testosterone therapy for masculinizing voice in transgender patients: A meta-analytic review

ABSTRACT Background: Testosterone therapy is the predominant treatment for voice masculinization in transgender patients. Although lowering of voice fundamental frequency (f0) occurs with testosterone therapy, evidence suggests voice and gender identity may not fully align—i.e., voice-gender congruence may not be achieved—with its use. Aim: This meta-analytic review evaluates the effectiveness of testosterone therapy to masculinize voice in transgender patients. Methods: Multiple electronic databases were queried (inclusion dates: from database inception up to October 27, 2017) to identify original research on voice masculinization using testosterone therapy. Nineteen articles were included in this meta-analytic review, which followed PRISMA guidelines. In addition to qualitative analyses, random effects proportion meta-analyses were performed on data related to f0, voice-gender congruence, voice problems, and satisfaction with voice. Results: A meta-analysis on f0 data showed after 1 year of testosterone therapy a combined estimate of 21% of participants (95% confidence interval [CI]: 5%–43%; I2: 59.9%) did not achieve cisgender male normative frequencies (f0 ≤ 131 Hz). Meta-analyses on incomplete voice-gender congruence and voice problems indicated combined estimates of 21% (95% CI: 10%–34%; I2: 0.0%) and 46% (95% CI: 14%–79%; I2: 90.2%), respectively. Regarding incomplete satisfaction with voice, a meta-analysis showed a combined estimate of 16% (95% CI: 7%–28%; I2: 0.0%). Discussion: We found that not all transgender patients using testosterone therapy to masculinize voice should expect f0 lowering to cisgender male normative frequencies after 1 year. The vocal transition may involve voice problems for many patients, and some might not achieve voice-gender congruence without additional, voice-specific intervention. Given these findings, a voice evaluation should occur prior to initiating testosterone therapy and involve counseling on expectations for voice. Transgender patients who pursue voice masculinization may need management from laryngology and speech and language therapy to improve voice-gender congruence, mitigate voice problems, and increase satisfaction with voice.