[Translation into Brazilian Portuguese and validation of the Work Limitations Questionnaire].

OBJECTIVES: To translate into Brazilian Portuguese, cross-culturally adapt, and evaluate the psychometric properties, reliability, and validity of the Work Limitations Questionnaire (WLQ).
METHODS: This cross-sectional observational study was performed in 2005 and 2006 at the Hospital São Paulo/Escola Paulista de Medicina of the Federal University of São Paulo, Brazil. Data from 150 individuals who were employed at the time of the study were obtained using the WLQ, the SF-36 (a generic quality of life questionnaire), and the SRQ-20 (used to screen for mental disorders). The WLQ has 25 items, which are divided into four domains: time management, physical demands, mental-interpersonal demands, and output demands. The questionnaires were administered as interviews to individuals without a university education, and were self-administered to individuals with a university degree. Descriptive statistics were used to characterize the sample. The intraclass correlation coefficient and Cronbach's alpha were used to assess reliability (internal consistency, test-retest, interobserver, and intraobserver agreement). The Pearson's correlation coefficient was used to assess construct validity.
RESULTS: The mean age of the subjects was 37.6 years (standard deviation, +/- 9.6 years), and 64.7% of the subjects were female. The mean number of years at the job held at the time of the interview was 8.6 (+/- 8.3 years); 60.7% of the subjects were satisfied with their job, and 94.0% had not missed work in the preceding two weeks. In comparison to completely healthy persons, the mean productivity loss reported by the study subjects was 4.2%. Interobserver agreement was significant and high (0.600 to 0.800) or very high (0.800 to 1.000) in all domains, except physical demands (r = 0.497, moderate agreement). Intraobserver agreement was not significant for the time management and physical demands domains. The correlations associated with intraobserver agreement were moderately significant (0.400 to 0.600). Internal consistency was very high (Cronbach's alpha = 0.800 to 1.000). There was a significant correlation between all the SF-36 questionnaire domains and the WLQ domains of time management, mental-interpersonal demands, and output demands as well as the WLQ index score. A positive correlation was also found between the WLQ domains of time management, mental-interpersonal demands, and output demands and a positive result (score >or= 7) on the SRQ-20.
CONCLUSION: The Brazilian Portuguese version of the WLQ is a reliable and valid scale to assess the impact of health problems on the productivity of Brazilian workers.