The correlation between FVC, FEV₁, and FEVR with Voice Handicap Index of myasthenia gravis patients

Background and objectives. Dysarthrophonia is a common manifestation of myasthenia gravis (MG), affecting patients' quality of life, especially those who use their voices frequently. Lung function is closely related to vocal function. This study analyzes the correlation between lung function and voice-related quality of life in MG patients. Materials and methods. This cross-sectional study included 23 clinically stable patients with mild to moderate MG based on Myasthenia Gravis Foundation of America (MGFA). Pulmonary function assessed was forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), and forced expiratory volume ratio (FEVR), measured using a portable digital spirometer. Voice-related quality of life was assessed using the Voice Handicap Index (VHI-30) questionnaire. Results. The average VHI score was 21.85 ± 23.24 in MG type IIA and 19.80 ± 20.60 in MG type IIB. The FEV₁ mean value was 72.54 ± 10.80 in MG type IIA and 53.15 ± 10.25 in MG type IIB. The mean FVC values in MG type IIA were 75.60 ± 7.11 and 53.57 ± 5.71 in MG type IIB. The mean FEVR values in MG type IIA were 79.67 ± 8.33 and 82.33 ± 10.92 in MG type IIB. There was no significant correlation between FVC, FEV₁, and FEVR with VHI (CI 95%, p > 0.05). Conclusions. There is no relationship between FVC, FEV₁, and FEVR with VHI in MG patients. Further research is needed to analyze other factors influencing voice-related quality of life in MG patients. A larger-scale study and objective measurements of voice function would be beneficial.