FLEX October 2023

257

Volume 90 Number 2 2014

Voice quality in early laryngeal cancer

use of a CO 2 laser. The operations were performed as described elsewhere (8, 9) by only 7 experienced senior surgeons. In short, the tumors were first split, and tumor tissue was removed down to a macroscopically healthy muscle layer. After tumor excision, small biopsy specimens were taken to ensure complete (R0) removal.

that a sample size of 30 patients per group could yield a significant difference in the primary endpoint between the groups. The statistical analyses were done with a PASW Sta tistics 18 computer program (SPSS Inc, Chicago, IL). Repeated measurements between the groups over time were tested with repeated-measures analysis of variance. When an assumption for sphericity was violated, the degrees of freedom were corrected with Greenhouse-Geisser estimates of sphericity. Frequency tables were compared with the c 2 test or Fisher exact test. Relationships between the aspects of voice quality (the GRBAS components), self-rated quality of voice, impact of voice quality on activities of daily living, and videolaryngostroboscopic findings were analyzed by computing the Pearson correlation coefficient ( r ). To assess interrater and intrarater reliability in judging voice quality, Cronbach a was calculated on each of the 5 dimensions of the GRBAS scale. The P values are 2-sided.

Evaluation of voice quality

The patients had prescheduled follow-up visits at 2-month to 3-month intervals at the hospital otorhinolaryngology outpatient clinics. Voice samples were collected at baseline and 6 and 24 months after treatment. The larynx was examined with videolaryngostroboscopy, and the patients filled in questionnaires. Expert-rated evaluation of voice was based on 3 sen tences read aloud at a comfortable speech loudness level. The sentences included 17 words and lasted about 14.5 seconds. Voice samples were uploaded onto a compact disk in a random order. A total of 150 voice samples were analyzed by 3 trained speech and language therapists with expertise in voice quality evaluation who were blinded to the treatment groups. Voice quality was assessed on the GRBAS scale, consisting of grade (G), reflecting overall voice quality; roughness (R); breathiness (B); asthenia (A); and strain (S). Ratings of these 5 aspects of voice quality varied from 0 (normal) to 3 (extremely abnormal) (10). The higher the score, the more dysphonic the voice. Interrater consistency was assessed by comparing the original ratings of all voice samples (150 items) between the raters. To assess intrarater consistency, the voice sam ples were randomized, after which the samples of 10 pa tients were randomly duplicated on a compact disk and reassessed by the raters. The patients rated their own voice quality (hoarseness) and assessed its impact on daily life using a 100-mm long visual analogue scale (VAS) with end anchors “no degree of” and “high degree of” hoarseness and inconvenience. The videolaryngostroboscopic findings were evaluated by a panel of 3 phoniatricians, who were blinded to the treatment groups and uninvolved with the treatments. Adduction and abduction movements of the vocal cords, the amplitude and the phase symmetry of the mucosal wave, glottal closure, and signs of vocal cord hyperfunction were each assessed on a scale from 0 (no pathology) to 3 (major pathology).

Results

Patients

Sixty patients entered the study between June 1998 and October 2008. Of these, 28 were randomly assigned to radiation therapy and 32 to TLS. Four patients were excluded from the analysis (1 was female; 3 withdrew consent), leaving 25 evaluable patients in the radiation therapy group and 31 in the TLS group (Fig. 1). The me dian age at study entry was 65 years (Table 1).

Expert-rated quality of voice

Before beginning the study treatments, the patients had generally more breathy and rough voices compared with the normal voice, but there was no significant difference between the groups. The mean scores in expert-rated overall voice quality (G), voice roughness (R), and strain (S) remained similar between the groups during follow-up, but patients treated with TLS had a more breathy voice than those who received radiation therapy (score 1.52 vs 0.28 2 years after treatment, P < .001) (Table 2). A statistically significant difference emerged also in asthenia (0.74 vs 0.11; P Z .003), but in both groups the absolute value was under 1, suggesting limited clinical relevance of this finding. No significant change in overall voice quality (G) occurred during follow-up, but voice breathiness and asthenia improved significantly with time in the radiation therapy group (from 1.17 at baseline to 0.28 2 years after treatment, P < .001; and from 0.56 to 0.11, P Z .001, respectively) but not in the TLS group. The degree of voice breathiness varied substantially. In the TLS group, 20 (74%) of the 27 evaluable patients had mildly or moderately breathy voice (score 1 or 2) 2 years after treatment, 2 (7%) patients had an extremely breathy

Statistical analysis

The primary analysis was intention-to-treat and involved all eligible patients who provided informed consent, were male, and had laryngeal cancer. We found the voice quality data available in the litera ture to be in part conflicting and to offer little guidance for estimation of the study sample size. Therefore, we were not able to perform formal power calculations. We estimated