RESUMO
This study describes the validity of a food frequency questionnaire (FFQ) in 93 low-income women (20-65 years), participating in a case-control study in São Paulo, Brazil. Two FFQ (FFQ1 and FFQ2, 12 months apart) and three 24-hour dietary recalls (24hR) were conducted between 2003 and 2004 to estimate dietary intake during the past year. The Pearson correlation coefficients (crude, energy-adjusted and de-attenuated) were used for comparisons between FFQ and 24hR. The agreement between the methods was further examined by the Bland-Altman analysis. For the assessment of long-term reliability, the energy-adjusted intra-class correlation coefficients were mostly around 0.40, but higher for vitamin A and folate (0.50-0.56). Energy-adjusted, attenuation-corrected Pearson validity correlations between FFQ and DR ranged from 0.30-0.54 for macronutrients to 0.20-0.48 for micronutrients, with higher value for calcium (0.75). There were small proportions of grossly misclassified nutrient intakes, while Bland-Altman plots indicated that the FFQ is accurate in assessing nutrient intake at a group level.
Assuntos
Inquéritos sobre Dietas/normas , Ingestão de Energia/fisiologia , Pobreza , Inquéritos e Questionários/normas , Adulto , Idoso , Brasil , Inquéritos sobre Dietas/métodos , Métodos Epidemiológicos , Feminino , Humanos , Pessoa de Meia-Idade , Adulto JovemRESUMO
This study describes the validity of a food frequency questionnaire (FFQ) in 93 low-income women (20-65 years), participating in a case-control study in São Paulo, Brazil. Two FFQ (FFQ1 and FFQ2, 12 months apart) and three 24-hour dietary recalls (24hR) were conducted between 2003 and 2004 to estimate dietary intake during the past year. The Pearson correlation coefficients (crude, energy-adjusted and de-attenuated) were used for comparisons between FFQ and 24hR. The agreement between the methods was further examined by the Bland-Altman analysis. For the assessment of long-term reliability, the energy-adjusted intra-class correlation coefficients were mostly around 0.40, but higher for vitamin A and folate (0.50-0.56). Energy-adjusted, attenuation-corrected Pearson validity correlations between FFQ and DR ranged from 0.30-0.54 for macronutrients to 0.20-0.48 for micronutrients, with higher value for calcium (0.75). There were small proportions of grossly misclassified nutrient intakes, while Bland-Altman plots indicated that the FFQ is accurate in assessing nutrient intake at a group level.
Este estudo compara a validade de questionário de freqüência alimentar (QFA) em 93 mulheres participantes de estudo caso-controle em São Paulo, Brasil. Dois QFA (12 meses de intervalo entre QFA1 e QFA2) e 3 recordatórios de 24 horas (R24h) foram obtidos entre 2003 e 2004. Coeficientes de correlação de Pearson (brutos, ajustados pelas calorias totais e com correção intra-indivíduos) foram utilizados na comparação entre os métodos. A concordância entre QFA e R24h foi avaliada pela análise de Bland-Altman. Na avaliação de reprodutibilidade em longo prazo, coeficientes de correlação intraclasse ajustados pelas calorias totais foram próximos de 0,40, com valores maiores para vitamina A e folato (0,50-0,56). Coeficientes de correlação de Pearson ajustados pelas calorias totais e de-atenuados variaram de 0,30-0,54 para macronutrientes a 0,20-0,48 para micronutrientes, com valores maiores para cálcio (0,75). Houve uma pequena proporção de erro de classificação, e a análise de Bland-Altman sugere que o QFA é adequado para a classificação do consumo de nutrientes para o grupo de indivíduos estudado.
