Validation of the Iranian Voice Quality of Life Profile into Brazilian Portuguese

To evaluate the psychometric properties of the Iranian Voice Quality of Life Profile (IVQLP) with Brazilian Portuguese (BP) speakers with voice complaints.

Cross-sectional observational study. Participants were 219 BP-speaking adults, divided into two groups based on the presence of voice complaints. The participants completed the IVQLP in BP (IVQLP-Br), voice-related quality of life (V-RQOL), and voice handicap index-10 (VHI-10) questionnaires. The IVQLP-Br was reapplied. The psychometric properties evaluated were reliability (internal consistency and test-retest), construct validity (structural validity, convergent and known-groups validity by hypothesis testing), and criterion validity (concurrent validity and determination of cutoff points).

Structural validity confirmed the structure of 43 items and three factors, with a residual standardized root mean square of 0.095. The internal consistency ranged from 0.823 (physical) to 0.977 (total). The test-retest reliability ranged from 0.855 to 0.949. Convergent validity showed moderate to strong positive correlations between the IVQLP-Br and the VHI-10 (ρ = 0.63-0.76; P < 0.001). In the concurrent validity analysis, a negative correlation was found with V-RQOL (P < 0.001). Known-groups validity indicated significantly higher scores in the group with voice complaints (P < 0.001). The areas under the curve ranged from 0.800 to 0.907. The cutoff points were 7.5 points for the physical factor, 23.5 points for the emotional factor, 17.5 points for the functional factor, and 50.5 points for the total score, with greater sensitivity in the physical factor, greater specificity in the functional factor, and greater accuracy in the total score.

The IVQLP-Br proved to be a valid and reliable tool for assessing voice-related quality of life in BP speakers.