This methodological, prospective, single-center study focused on translation and semantic validation of the Brazilian Portuguese SOSGOQ 2.0 through cognitive interviews with patients diagnosed with spinal metastases. The study was approved by the Research Ethics Committee of Hospital Israelita Albert Einstein (CAAE: 83235924.2.0000.0071; #7.364.227) and conducted by the AO Spine Latin America Tumor Study Group (Grant ID 295). The study followed the COREQ guidelines.⁽¹⁶⁾

The principal investigator, a bilingual orthopedic spine surgeon, conducted all cognitive interviews. No prior therapeutic relationship existed between the interviewer and the participants, which helped minimize response bias. Training in qualitative interview techniques was completed before data collection.

The interviewer disclosed the researcher role rather than a treating physician role and explained the academic objectives of the study to promote participant comfort in providing honest feedback about the questionnaire.

The study followed the methodology proposed by Beaton et al.⁽¹⁵⁾ for cross-cultural adaptation of instruments and was structured into sequential phases.

In Phase 1 (forward translation), two independent Brazilian translators fluent in English and blinded to the study objectives performed conceptual translations of the original SOSGOQ 2.0, prioritizing equivalence of meaning rather than literal word-for-word translation.

In Phase 2 (synthesis), the translated versions were jointly reviewed by the two translators and two spine surgeon researchers until consensus was reached on the first Brazilian Portuguese version.

In Phase 3 (back translation), two native English-speaking translators fluent in Portuguese and blinded to the original instrument independently translated the Portuguese version back into English. These versions were compared and reconciled by consensus to produce a single back-translated version.

In Phase 4 (expert committee review), the English back-translated version underwent review by the original Brazilian translators after a 30-day interval to ensure consistency with the original instrument. This process resulted in consolidation of the final Portuguese version of SOSGOQ 2.0 (Appendix 1).

The final Portuguese version of SOSGOQ 2.0 was administered to five patients with spinal metastases treated at Hospital Vila Santa Catarina, a public oncology hospital managed by Hospital Israelita Albert Einstein.

Inclusion criteria included age >18 years, literacy in Portuguese, diagnosis of spinal metastases treated with surgery and/or radiotherapy, and the ability to provide informed consent.

Exclusion criteria included cognitive impairment that prevented provision of informed consent, inability to read Portuguese, and acute medical instability.

Purposive sampling was used to recruit patients with diverse demographic characteristics and disease presentations to ensure broad representation of the target population.

All interviews were conducted in a private consultation room at Hospital Municipal Gilson de Cássia Marques de Carvalho, separate from clinical treatment areas, to ensure patient comfort and confidentiality.

Cognitive interviews followed an established methodology based on the frameworks proposed by Willis⁽¹⁷⁾ and Beatty et al.⁽¹⁸⁾ for questionnaire validation, using think-aloud and verbal probing techniques.

After independent completion of the printed questionnaire, each participant underwent a semi-structured cognitive interview lasting 10-15 min. The interview aimed to assess clarity and comprehensibility of each item, evaluate appropriateness of terminology, and identify any doubts, ambiguities, or discomfort experienced during completion.

A standardized interview guide covered five domains: general comprehension, cultural appropriateness, clinical relevance, adequacy of response options, and overall assessment (Appendix 2).

All interviews were conducted individually. The principal investigator documented responses in detailed field notes, and questionnaire completion time was recorded to assess feasibility.

Interview data underwent thematic content analysis according to established qualitative research methodology.⁽¹⁹⁾ Systematic coding identified recurring themes related to comprehensibility, cultural relevance, and clinical applicability.

Feasibility assessment included quantitative measures such as questionnaire completion time, completion rate, and the frequency of clarification requests.

All participants received information about the objectives, procedures, risks, and benefits of the study and provided written informed consent before participation. The study protocol was reviewed and approved by the institutional research ethics committee.

Five patients completed the study between March and April 2024. All eligible patients agreed to participate, resulting in a participation rate of 100%. Participant demographics and clinical characteristics appear in table 1.

All five participants (100%) completed the 20-item SOSGOQ 2.0 without assistance or clarification during the completion process. No items were left blank, and no confusion requiring intervention occurred.

The mean completion time was 12±3 min (range: 9-15 min). All participants completed the questionnaire within the anticipated timeframe for clinical feasibility.

No participant requested clarification of the instructions or item content during questionnaire completion, which indicates adequate clarity of the translated version.

Thematic analysis of the cognitive interviews identified three primary themes related to semantic validity and cultural appropriateness of the Brazilian Portuguese SOSGOQ 2.0.

High comprehensibility and linguistic clarity emerged as a consistent theme across interviews. All participants demonstrated clear understanding of the questionnaire items without the need for clarification, repetition, or explanation. The translated terminology was consistently understood across different educational levels.

Cultural and contextual relevance also emerged from participant feedback. Participants confirmed that the questionnaire items appropriately reflected healthcare experiences and cultural contexts in Brazil. The translated version maintained relevance within the Brazilian public healthcare system.

Clinical applicability and symptom recognition represented a third major theme. Participants recognized a clear correlation between the questionnaire items and the clinical symptoms and functional limitations associated with spinal metastases. All participants confirmed the clinical relevance of the assessed domains.

None of the participants suggested modifications to wording, phrasing, or terminology. The translated version maintained conceptual equivalence with the original instrument while using culturally appropriate Brazilian Portuguese expressions. Participants confirmed that all 20 items addressed symptoms and functional limitations relevant to their experience with spinal metastases, and no suggestions were made for item addition or removal.

No linguistic modifications to the translated text were required based on feedback from the cognitive interviews. Semantic validation therefore confirmed adequacy of the translation process.

No cultural adaptations were considered necessary, as participants confirmed appropriateness of all content within the Brazilian healthcare context.

This study significantly extends the work of Batista et al.⁽¹³⁾ through several methodological enhancements. Batista et al. provided translation and cross-cultural adaptation using the Beaton et al. framework,⁽¹⁵⁾ whereas the present study advances the field in several ways. First, the study employed the internationally recognized Beaton et al. methodology,⁽¹⁵⁾ which includes rigorous forward and back translation with expert committee review. Second, the study conducted the first clinical application of the instrument in patients diagnosed with spinal metastases. Third, systematic cognitive interviews followed COREQ guidelines⁽¹⁶⁾ with thematic analysis of qualitative data. Fourth, the study provided empirical evidence of semantic validity through direct patient feedback.

Batista et al. also acknowledged as a limitation that "the instrument was not submitted to psychometric validation" and recommended future studies to conduct clinical validation. The present study addresses this gap by establishing an essential semantic validation foundation for future large-scale psychometric investigations. The combination of rigorous translation methodology and clinical validation through patient cognitive interviews provides stronger evidence supporting linguistic equivalence and cultural appropriateness of the Brazilian Portuguese SOSGOQ 2.0.

The cognitive interview methodology used in this study provides important evidence of semantic validity and the extent to which questionnaire items are understood as intended by the target population.⁽²⁰⁾ The findings indicate that the Brazilian Portuguese SOSGOQ 2.0 demonstrates high semantic validity, as all participants understood the items clearly and recognized their clinical relevance. This aspect is particularly important for patient-reported outcome measures, in which misunderstanding of items may compromise data quality and clinical utility.⁽²¹⁾

The average completion time of 12 min supports feasibility for use in busy oncology settings. This duration is comparable to that reported for other validated spine-specific questionnaires and remains acceptable for routine clinical use.^(7,8) The absence of requests for assistance or clarification during completion further indicates that the instrument can be reliably self-administered across different educational levels.

An important finding of this study was confirmation of cultural appropriateness within the Brazilian healthcare context. Participants indicated that the questionnaire items reflected their experiences within the Brazilian public healthcare system. Cultural alignment represents a key requirement for patient-reported outcome measures, because cultural mismatch may compromise validity even when linguistic translation remains accurate.⁽²²⁾

The diversity of participant educational backgrounds, which ranged from primary school to university level, and the consistent understanding of the questionnaire items suggest broad applicability across different socioeconomic groups in Brazil. This aspect is particularly relevant for the Brazilian public healthcare system, which serves a highly diverse patient population.

This study was conducted in collaboration with an international group of researchers and members of the Latin America Spine Tumor Study Group. The inclusion of authors from different countries, including contributors whose native language is not Portuguese, reflects the original objective of developing a standardized methodological instrument suitable for multicenter studies across Latin America. This collaboration strengthened methodological rigor, expanded the cross-cultural applicability of the translated version, and promoted scientific integration across the region.

The validated Brazilian Portuguese SOSGOQ 2.0 may also prove applicable to other Portuguese-speaking countries, although this possibility requires confirmation through future verification studies. Such expansion could facilitate international research collaboration and comparative effectiveness studies across Portuguese-speaking populations.

This study represents the semantic validation phase of instrument adaptation recommended by the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines for patient-reported outcome measures.⁽²³⁾ Although the qualitative validation provides important evidence regarding comprehensibility and cultural appropriateness, comprehensive psychometric validation, including assessment of reliability, validity, and responsiveness, requires larger sample sizes according to COSMIN standards.

According to COSMIN methodology, semantic validation studies typically include 5-10 participants for cognitive interviews to evaluate comprehensibility. In contrast, psychometric validation requires substantially larger samples, with at least 100 patients for reliability assessment and more than 150 patients for construct validity testing.^(23,24) The present study therefore provides an important foundation for future such larger-scale quantitative validation studies, which are currently underway with expanded patient recruitment across multiple Brazilian centers.

The single-center design, although appropriate for semantic validation, limits generalizability across different regions and healthcare settings in Brazil. Future multicenter studies should confirm these findings across diverse geographical and institutional contexts.

The availability of a semantically validated Brazilian Portuguese SOSGOQ 2.0 enables spine oncology centers in Brazil to collect standardized patient-reported outcome data, which supports evidence-based clinical decision-making and research. The instrument can facilitate systematic assessment of treatment outcomes in patients with spinal metastases, comparison of therapeutic interventions within Brazilian healthcare settings, participation in international multicenter studies, and development of Brazilian clinical guidelines for spinal oncology care.

Future research should focus on large-scale psychometric validation following COSMIN guidelines, establishment of Brazilian population norms and minimal clinically important differences, responsiveness testing in longitudinal studies, validation within specific cancer subtypes and treatment modalities, and implementation research in routine clinical practice settings.

The semantic validation approach used in this study follows established international precedents for questionnaire adaptation, in which qualitative assessment precedes quantitative psychometric testing.⁽²⁵⁾ This sequential validation strategy ensures that linguistic and cultural barriers are addressed before large-scale statistical validation studies are undertaken.