Validation of the Functional Assessment Short Test (FAST) for the Brazilian general population

26/08/2026

AI Summary

FAST demonstrated validity and reliability in a Brazilian non-clinical young adult sample, supporting its use in mental health research and prevention.
Exploratory factor analysis identified five domains: Autonomy, Work, Cognition, Finances, and Interpersonal Relations/Leisure; KMO 0.919, 63% variance.
CFA showed excellent fit (CFI 0.957, TLI 0.952, RMSEA 0.038, SRMR 0.050), high internal consistency (α 0.871), and convergent validity with SF-12 mental (ρ -0.445).

AI Summary

The Functional Assessment Short Test (FAST) is widely used to assess functional impairment across multiple domains, particularly in bipolar disorder.

Confirmatory factor analysis demonstrated excellent model fit: Comparative Fit Index (CFI) = 0.957, Tucker-Lewis Index (TLI) = 0.952, Root Mean Square Error of Approximation (RMSEA) = 0.038 (90% confidence interval: 0.035-0.041), Standardized Root Mean Square Residual (SRMR) = 0.050, and Goodness of Fit Index (GFI) = 0.993.

CONCLUSIONS: The findings provide robust evidence of validity and reliability of the FAST in the non-clinical population, supporting further investigation of its use in mental health research and preventive settings involving young adults in Southern Brazil.

Basic summary

Trends Psychiatry Psychother. 2026 Aug 26. doi: 10.47626/2237-6089-2026-1393. Online ahead of print.

ABSTRACT

BACKGROUND: Functional capacity refers to an individual’s ability to perform daily activities essential for independent living and social participation. The Functional Assessment Short Test (FAST) is widely used to assess functional impairment across multiple domains, particularly in bipolar disorder.

OBJECTIVE: To psychometrically validate the FAST in the non-clinical population.

METHODS: A total of 1,560 young adults were assessed through standardized interviews. Exploratory and confirmatory factor analyses were conducted using polychoric matrices and robust estimators.

RESULTS: Exploratory analysis identified a five-factor structure (Autonomy, Work, Cognition, Finances, and Interpersonal Relations/Leisure), with excellent sampling adequacy (KMO = 0.919) and 63% explained variance. Confirmatory factor analysis demonstrated excellent model fit: Comparative Fit Index (CFI) = 0.957, Tucker-Lewis Index (TLI) = 0.952, Root Mean Square Error of Approximation (RMSEA) = 0.038 (90% confidence interval: 0.035-0.041), Standardized Root Mean Square Residual (SRMR) = 0.050, and Goodness of Fit Index (GFI) = 0.993. Factor loadings ranged from 0.432 to 0.887, and internal consistency was high (α = 0.871; ω = 0.892). Convergent validity was supported by a moderate negative correlation with the mental component of the SF-12 (ρ = -0.445; p < 0.001).

PMID:42644657 | DOI:10.47626/2237-6089-2026-1393

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