Reliability and validity of a semi-quantitative FFQ for sodium intake in low-income and low-literacy Brazilian hypertensive subjects

Abstract

Objective: To assess the reliability and validity of an FFQ to evaluate dietary patterns of Na consumption among low-income and low-literacy Brazilian hypertensive subjects. Design: The initial FFQ was submitted to content analysis with the pre-test administered to fifteen subjects. Reliability was evaluated according to the reproducibility criterion, with interviewer administration of the FFQ twice within a 15 d interval. Validity was assessed against a 24 h recall (132 subjects), a 3 d diet record (121 subjects) and a biomarker (24 h urinary Na; 121 subjects). To test the correlation with the biomarker, discretionary salt was added to the FFQ Na values. Setting: A large urban teaching hospital in south-eastern Brazil. Subjects: The study was based on 132 randomly selected subjects (eighty-three women and forty-nine men) aged 18 to 85 years. Results: Kappa coefficients ranged from 0?79 to 0?98, confirming the reproducibility of the FFQ. There was no correlation between urinary Na excretion, the FFQ and the 24 h recall for the general sample, although significant correlations had been observed when methods were summed up (24 h recall 1 discretionary salt 1 FFQ; 0?32, P 5 0?01). The addition of discretionary salt significantly improved the biomarker-based FFQ validity, with correlation coefficients varying from 0?19 (general sample) to 0?31 (female sub-sample). Conclusions:The developed FFQ demonstrated satisfactory evidence of validity and reliability and can be used as an important complementary tool for the evaluation of Na intake among Brazilian hypertensive subjects.

Characterization of salt consumption among hypertensives according to socio-demographic and clinical factors

“…Among the factors related to the development and progression of hypertension, the elevated consumption of salt has been directly associated with the increase in blood pressure levels and the occurrence of cardiovascular complications (2)(3)(4)(5)(6)(7) . Although there are international and Brazilian recommendations for the limiting of sodium consumption both for the population in general and for hypertensive individuals of 5g and 4g respectively (8)(9) , studies with different populations show a consumption of sodium which is higher than the recommended (9)(10)(11)(12)(13)(14) , with an average of up to 4600mg of sodium (11.5g of salt)/day (7) . An important study in the area, the INTERSALT (2)(3) , undertaken with 10,079 men and women between 20 and 59 years of age, from 52 centers, aimed at testing hypotheses within and between populations regarding the relationship between 24-hr urinary sodium excretion and levels of blood pressure.…”

Conceptual framework for research and clinical practice concerning cardiovascular health-related behaviors

“…A disadvantage of this objective measure is that it reflects one-time food consumption and does not identify the food sources, which is only possible through self-report tools. In addition to validating self-report measures, this study also revealed very high salt intake-about 12 g salt/a day-among the participants, three times greater than the value recommended for hypertensive individuals (19) .…”

“…Evidence found in previously mentioned studies (19)(20) grounded step 1 of the intervention mapping: salt intake is high among hypertensive individuals and the main source of consumption is adding salt while preparing food. A reduction in adding salt is explained in 22% of the cases by motivation (intention to act), which in turn is explained by the constructs of self-efficacy and habit.…”

“…It presented the development and validation of self-report measures of salt intake. These measures were validated through correlation tests with 24-hr urinary sodium excretion, which is considered the gold standard for salt intake (19) . A disadvantage of this objective measure is that it reflects one-time food consumption and does not identify the food sources, which is only possible through self-report tools.…”

Sodium and potassium intake estimated using two methods in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

“…24 In a study in Porto Alegre, in southern Brazil, Micheli and Rosa 25 did not find good agreement between the food register and 12-hour urinary sodium excretion.…”