Minimal Clinically Important Differences in CAPE-V Auditory-Perceptual Ratings of Voice Quality

This study aimed to determine the minimally detectable changes (MDCs) and minimal clinically important differences (MCIDs) of auditory-perceptual ratings of voice quality using the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) scales (i.e., Overall Severity, Roughness, Breathiness, Strain).

Participants (n = 63) included patients diagnosed with phonotraumatic vocal fold lesions who underwent either voice therapy or laryngeal surgery and reported posttreatment voice improvements. Nine expert voice-specialized speech-language pathologists rated the pre- and posttreatment voice samples using CAPE-V scales (i.e., via 100-mm visual analog scales with included textual labels for severity). Separately, raters judged the magnitude of perceived change between pre- and posttreatment samples using Jaeschke's Global Ratings of Change Scale, which served as the anchor for MCID calculations. Intrarater reliability and the standard error of measurement were used to calculate MDCs at the 95% confidence interval for each dimension. Receiver operating characteristic curves were used to identify MCID thresholds, which were defined as values that optimized sensitivity and specificity while also exceeding the MDC.

MDC values, representing thresholds for determining whether a true change has occurred, were 14.9 mm for Overall Severity, 14.6 mm for Roughness, 12.1 mm for Breathiness, and 18.7 mm for Strain. MCID thresholds, representing thresholds for determining clinically meaningful change, were 16.5 mm for Overall Severity, 16.5 mm for Roughness, and 15.5 mm for Breathiness. All potential MCID thresholds for Strain were smaller than the MDC value; thus, a valid MCID threshold was not obtained.

This study represents the first known attempt to establish MDC and MCID thresholds for auditory-perceptual ratings of voice quality. The thresholds provide guidance for determining whether real and meaningful changes in voice quality have occurred in patients undergoing treatment for phonotraumatic voice disorders. Future research should explore these values across various voice disorder populations and severity levels and incorporate patient-reported outcomes as anchors to enhance clinical decision making and treatment outcomes in voice rehabilitation.