[Psychometric properties of the quality of life assessment instrument: 12-item health survey (SF-12)].

This article aims to assess the psychometric properties of the 12-Item Health Survey (SF-12). Data from an epidemiological oral health survey conducted in 2008/2009 in the municipality of Montes Claros, MG were used, consisting of 2157 individuals of both sexes. The relational structure of the SF-12 was assessed by Factor Exploratory Analysis (FEA), the reliability was assessed using Cronbach's alpha coefficient and Pearson's correlation coefficient was adopted in order to assess the correlations between each questionnaire item and the final scores. The validity of the construct was investigated by comparing the physical (PCS) and mental (MCS) component scores of the SF-12 among population subgroups, using the Mann-Whitney and Kruskal-Wallis tests. The PCS and MCS domains presented averages (standard deviation), respectively, equal to 49.6 (9.0) and 51.9 (8.6). Cronbach's alpha coefficient (α= 0.836) presented a high degree of reliability. The relational structure was explained by two latent factors, which explained the 58.36% of the total variance. The psychometric properties of the SF-12 suggest that this is a sensitive tool to assess the different QL levels, is reliable, has satisfactory internal consistence and is fast and easy to use.