Introduction Territory view based on families vulnerability strata allows identifying different health needs that, in their turn, can guide healthcare at primary care scope. Although there are instruments aimed at measuring family vulnerability, they still need robust validity evidences; therefore, they represent a limitation for usability in a country showing multiple socioeconomic and cultural realities, such as Brazil. The present study introduces the development and search for evidences about the validity of the Family Vulnerability Scale for Brazil, known as EVFAM-BR. Methods Items were generated through exploratory qualitative study carried out with 123 professionals. Collected data subsidized the generation of 92 initial items that were subjected to a panel of multi-regional and multi-disciplinary judges (n = 73) to calculate the Content Validity Ratio (CVR) – this process resulted in a version of the scale comprising 38 items. Subsequently, it was applied to 1,255 individuals to find evidences about the internal-structure validity by using the Exploratory Factor Analysis (EFA). Dimensionality was assessed through Robust Parallel Analysis and the model was tested through cross-validation to find EVFAM-BR’s final version Results The final version comprised 14 items distributed into four domains, with explained variance of 79.02%. All indicators were within adequate and satisfactory limits, without any cross-loading and Heywood Case issues. Reliability indices also reached adequate levels (α = 0.71; ω = 0.70; glb = 0.83 and ORION ranging from 0.80 to 0.93, between domains). Instrument’s score was subjected to normalization, and it pointed towards three vulnerability strata (0 to 4 – Low; 5 to 6 – Moderate; 7 to 14 - High). Conclusion The scale showed satisfactory validity evidences, which were consistent, reliable ad robust; it led to a synthesized instrument capable of accurately measuring and differentiating family vulnerability in the primary care territory, in Brazil.

The authors have declared no competing interest.

This work was supported by the Program of Support for the Institutional Development of the Unified Health System (Law No. 12,101, of November 27, 2009), through Ordinance No. 3,362, of December 8, 2017 –Technical Opinion No. 2 /2021 - CGGAP/DESF/SAPS/MS (0019478128) and dispatch SAPS/GAB/SAPS/MS (0019480381). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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The study was approved by the Ethics Research Committee of Hospital Israelita Albert Einstein, which was approved on October 22, 2019 (n 3.674.106, CAAE 12395919.0.0000.0071). Oral consent was obtained.

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