Multi-dimensional investigation of the clinical effectiveness and prognostic factors of voice therapy for benign voice disorders

Abstract

Voice therapy is frequently recommended as the first-line treatment for benign voice disorders. This study investigated the clinical effectiveness of voice therapy and the prognostic factors of treatment outcomes. We recruited 103 consecutive patients with voice disorders, namely vocal nodules, polyps, and muscle tension dysphonia (MTD), from September 2014 to July 2016. All the patients received voice therapy as the primary treatment. Treatment outcomes were evaluated using auditory perceptual evaluation, acoustic analysis, maximum phonation time, and 10-item voice handicap index (VHI-10). Clinical effectiveness of voice therapy was defined by either 1) a posttreatment VHI-10 score ≤ 10 points or 2) decline of VHI-10 ≥ 4 points. After voice therapy, VHI-10 and perceptual rating of voice quality improved significantly (p<0.05) in the three disease categories. In patients with nodules, all the outcome parameters improved significantly (p<0.05). Patients with good adherence to voice therapy (attending more than four sessions) had a significantly higher effectiveness than those with poor adherence (87% vs. 64%, p<0.05). Patients with high occupational vocal demand also demonstrated a better effectiveness than those with routine vocal demand (90% vs. 70%, p<0.05). Subsequent multivariate analyses revealed that adherence and vocal demand were independently and significantly correlated with clinical effectiveness (p=0.03). Voice therapy is effective for patients with vocal nodules, polyps, and MTD. Adherence to voice therapy and occupational vocal demand are significant prognostic factors for treatment outcomes.