Introduction.

Thyca-QoL is a specific instrument to assess QoL in thyroid cancer patients, but it is not validated in Spanish language. The aim was to assess the psychometric properties of the Thyca-QoL.

Methods.

This is a prospective cross-sectional study. The Thyca-QoL was translated and adapted to Spanish language. A psychometric validation using an exploratory principal axis factor analysis and confirmatory analysis, concurrent validation compared with EORTC QLQ-C30 and a test-retest reliability assessment was done.

Results.

A total of 296 patients were included. Exploratory factor analysis showed a seven-factor solution with good diagnostic tests results. Cronbach´s alpha for the global scale was 0.86. The comparison between the Thyca-QoL and the EORTC QLQ-C30 demonstrated a high correlation (rho= 0.75) and coefficient for test-retest was 0.87.

Discussion.

The validation process followed all the methodological steps necessary to guarantee the performance of the instrument. The measurements of the internal validity, reliability, and reproducibility reached similar results as the original validation. The factor analysis showed a solution with seven factors that resembles the original results. Reproducibility was high for voice, sympathetic, sex, and chilliness domains and moderate for the others; the instrument had the ability to discriminate between clinical conditions.

Conclusion.

The spanish version of the thyroid-cancer-specific Thyca-QoL is a reliable and objective instrument to be used in clinical practice and for research objectives in Spanish speaking patients.

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