Incidence of Hoarseness After General Spine Surgery: Interim Report of Prospective Observational Study

Hoarseness can occur after spinal surgery under general anesthesia, which has been assessed through self-report measures based on questionnaires. Given the inherent biases associated with self-report instruments, there is a need for more objective measures to assess hoarseness.

Single institute, a prospective observational study was planned to include 427 patients after spine surgery. This interim analysis was planned to include 215 patients who met the inclusion criteria. All subjects included in this study submitted a questionnaire of Korean Voice Handicap Index (KVHI)-10. Voice analysis including low or high pitch (Herz), frequency variation rate (jitter), amplitude variation rate (Shimmer), and noise-to-harmonic ratio (NHR) was performed with a software of Pratt.

This interim report enrolled a total of 215 patients who met the inclusion criteria, and among them, 162 patients (75.5%) were subjected to interim analysis after excluding those with data loss (8 patients), operation cancellation (3 patients), and loss to follow-up (42 patients). The incidence of hoarseness was 35.0% on postoperative day (POD)0 and 5.5% on POD30. In the acoustic parameters analyzed, hertz and jitter were significantly positively correlated with the KVHI-10 scores on POD0, while only the jitter value significantly correlated with POD30. The optimal cutoff values of the acoustic parameter on POD30 from the receiver operating characteristic curve were 0.65% in jitter, 4.67% in shimmer, and 16.96 dB in NHR.

This study revealed a correlation between objective acoustic parameters obtained from voice analysis and subjective questionnaire scores for hoarseness.