Cross-cultural adaptation of the Skin Cancer Index into Brazilian Portuguese for patients with cervicofacial nonmelanoma skin cancer

Abstract

Purpose: This study aimed to translate the Skin Cancer Index (SCI) into Portuguese, adapt it for Brazilian culture, and clinically validate it.

Methods: A five-stage cross-cultural adaptation model was followed, with subsequent clinical validation. Inter-rater agreement was assessed using the content validity index (CVI). The hypothesis of the non-inferiority of the CVI at 80% probability level was evaluated using an exact binomial test. We used Spearman's rank-order and Pearson's product-moment correlation analysis, internal consistency using McDonald's ω and Cronbach's α metric, and construct validity using confirmatory factor analysis. The factorial model was validated using the chi-squared test, root mean square error of approximation (RMSEA), comparative fit index (CFI), and standardized root mean square residual (SRMR).

Results: The first stage yielded two independent translations. After synthesis, back-translation, and review, the prefinal version was tested on 40 patients. Inter-rater agreement indices on content validity were significantly higher than 80% (p < 0.05). The SCI remained stable, and the Spearman's rank-order (r_s), Pearson product-moment (r), and intraclass correlation coefficients were > 0.9, indicating excellent reliability. The reliability of McDonald's ω was considered ideal (> 0.8) in all subdimensions and scale. Cronbach's α was considered ideal in the "Emotional" and "Social" subdimensions and scale. Construct validity was observed in all subdimensions and scale through the criteria (χ²) p value > 0.05, RMSEA < 0.08, CFI ≥ 0.9, and SRMR ≤ 0.08.

Conclusion: The cross-cultural adaptation of the SCI to Portuguese for Brazilian culture showed content validity and reliability, contributing to quality of life assessment in patients with NMSC.

Keywords: Cross-cultural adaptation model; Nonmelanoma skin cancer; Portuguese; Skin Cancer Index.