Interaction Between Patient-Related and Surgical Factors in the Pattern of Voice Recovery Following Thyroidectomy: A Prospective Cohort Study

Background: A substantial proportion of patients experience persistent voice-related symptoms after thyroidectomy, even without clinically detectable laryngeal nerve injury. Identifying factors associated with delayed voice recovery is therefore important, as postoperative voice alterations may influence vocal performance and occupational voice use. This study examined the associations of patient-related (age, sex, body mass index [BMI]) and surgical variables (thyroid volume, type, and duration of surgery) with postoperative voice recovery stage within a six-month follow-up period. Methods: This prospective cohort study included 292 consecutive adults undergoing thyroidectomy at a tertiary referral center with normal preoperative voice and laryngeal findings. Patients with prior neck surgery, pre-existing voice disorders, reflux disease, or intraoperative laryngeal nerve injury were excluded. Objective voice assessment was performed multidimensionally at four predefined postoperative time points. The recovery stage was defined ordinally according to the first follow-up demonstrating normalization of all objective voice parameters. Multinomial logistic regression was used to examine multivariable associations and interactions between BMI and surgical variables. Results: Three regression models examined interactions between BMI and surgical variables, with recovery stage 4 (no normalization by six months) as the reference category. All three models were statistically significant (χ2(15) ≥ 86.32, p < 0.001). Duration of surgery was independently associated with recovery stage across models, with longer surgery associated with lower odds of recovery at stages 2 and 3 relative to stage 4 (p ≤ 0.041). Thyroid volume was also associated with recovery, with higher volume associated with greater odds of stage 1 versus stage 4 recovery (p = 0.008). Significant interactions were observed between BMI and duration of surgery (LR χ2(3) = 12.10, p = 0.007) and between BMI and type of surgery (LR χ2(3) = 15.17, p = 0.002), both driven by the comparison of stage 3 with stage 4. No significant interaction was found between BMI and thyroid volume (p = 0.294). Conclusions: Both patient-related (BMI) and surgical factors were associated with postoperative voice recovery stage. The association between BMI and recovery differed according to surgical duration and type, but not thyroid volume. These findings may support risk stratification and more tailored postoperative monitoring of objective postoperative voice recovery. Future multicenter studies using appropriate ordinal regression models and interval-censored survival methods are warranted to further clarify individualized recovery patterns following thyroidectomy.