Food insecurity, weight control practices and body mass index in adolescents.

OBJECTIVE: We investigated whether experienced food insecurity was associated with weight control behaviour of adolescents. DESIGN: A national survey of 16-year-old students with the six-item food security scale, questions concerning intentions of trying to change weight, physical activity patterns, and measurement of height and weight. SETTING: Representative sample of 29 schools in Trinidad, West Indies. SUBJECTS: Data analysed for 1903 subjects including 1484 who were food-secure and 419 who were food-insecure. RESULTS: In the whole sample, food security status did not vary by body mass index (BMI) category. 'Trying to gain weight' and 'spending most free time in activities involving little physical effort' were each associated with lower BMI. 'Trying to gain weight' was more frequent in food-insecure subjects (135, 32%) than in food-secure subjects (369, 25%, P = 0.012). After adjustment for BMI, age, sex, ethnicity and socio-economic variables, the adjusted odds ratio (OR) of 'trying to gain weight' for food-insecure subjects was 1.39 (95% confidence interval (CI) 1.07-1.82, P = 0.014). Food-insecure subjects (197, 47%) were more likely than food-secure subjects (575, 39%) to report that most of their free time was spent doing things that involved little physical effort (P = 0.003). This association was not explained by adjustment for BMI, age, sex and ethnicity (OR = 1.41, 95% CI 1.13-1.76, P = 0.002) or additional socio-economic variables (OR = 1.27, 95% CI 1.02-1.57, P = 0.033). CONCLUSIONS: Adolescents who experience food insecurity are more likely to intend to gain weight but engage in less physical activity than food-secure subjects with the same BMI.

The 18 Household Food Security Survey items provide valid food security classifications for adults and children in the Caribbean.

BACKGROUND: We tested the properties of the 18 Household Food Security Survey (HFSS) items, and the validity of the resulting food security classifications, in an English-speaking middle-income country. METHODS: Survey of primary school children in Trinidad and Tobago. Parents completed the HFSS. Responses were analysed for the 10 adult-referenced items and the eight child-referenced items. Item response theory models were fitted. Item calibrations and subject scores from a one-parameter logistic (1PL) model were compared with those from either two-parameter logistic model (2PL) or a model for differential item functioning (DIF) by ethnicity. RESULTS: There were 5219 eligible with 3858 (74%) completing at least one food security item. Adult item calibrations (standard error) in the 1PL model ranged from -4.082 (0.019) for the 'worried food would run out' item to 3.023 (0.042) for 'adults often do not eat for a whole day'. Child item calibrations ranged from -3.715 (0.025) for 'relied on a few kinds of low cost food' to 3.088 (0.039) for 'child didn't eat for a whole day'. Fitting either a 2PL model, which allowed discrimination parameters to vary between items, or a differential item functioning model, which allowed item calibrations to vary between ethnic groups, had little influence on interpretation. The classification based on the adult-referenced items showed that there were 19% of respondents who were food insecure without hunger, 10% food insecure with moderate hunger and 6% food insecure with severe hunger. The classification based on the child-referenced items showed that there were 23% of children who were food insecure without hunger and 9% food insecure with hunger. In both children and adults food insecurity showed a strong, graded association with lower monthly household income (P < 0.001). CONCLUSION: These results support the use of 18 HFSS items to classify food security status of adults or children in an English-speaking country where food insecurity and hunger are more frequent overall than in the US.

The 18 Household Food Security Survey items provide valid food security classifications for adults and children in the Caribbean

BACKGROUND: We tested the properties of the 18 Household Food Security Survey (HFSS) items, and the validity of the resulting food security classifications, in an English-speaking middle-income country. METHODS: Survey of primary school children in Trinidad and Tobago. Parents completed the HFSS. Responses were analysed for the 10 adult-referenced items and the eight child-referenced items. Item response theory models were fitted. Item calibrations and subject scores from a one-parameter logistic (1PL) model were compared with those from either two-parameter logistic model (2PL) or a model for differential item functioning (DIF) by ethnicity. RESULTS: There were 5219 eligible with 3858 (74%) completing at least one food security item. Adult item calibrations (standard error) in the 1PL model ranged from -4.082 (0.019) for the 'worried food would run out' item to 3.023 (0.042) for 'adults often do not eat for a whole day'. Child item calibrations ranged from -3.715 (0.025) for 'relied on a few kinds of low cost food' to 3.088 (0.039) for 'child didn't eat for a whole day'. Fitting either a 2PL model, which allowed discrimination parameters to vary between items, or a differential item functioning model, which allowed item calibrations to vary between ethnic groups, had little influence on interpretation. The classification based on the adult-referenced items showed that there were 19% of respondents who were food insecure without hunger, 10% food insecure with moderate hunger and 6% food insecure with severe hunger. The classification based on the child-referenced items showed that there were 23% of children who were food insecure without hunger and 9% food insecure with hunger. In both children and adults food insecurity showed a strong, graded association with lower monthly household income (P < 0.001). CONCLUSION: These results support the use of 18 HFSS items to classify food security status of adults or children in an English-speaking country where food insecurity and hunger are more frequent overall than in the US.

Self-administration of a food security scale by adolescents: item functioning, socio-economic position and food intakes.

OBJECTIVE: To evaluate the reliability and validity of a six-item food security scale when self-administered by adolescents. DESIGN: Cross-sectional questionnaire survey including the six-item food security measure, socio-economic variables and a food-frequency questionnaire. SETTING: Representative sample of 29 schools in Trinidad. SUBJECTS: In total 1903 students aged approximately 16 years. RESULTS: Item affirmatives ranged from 514 (27%) for the 'balanced meal' item to 128 (7%) for the 'skipped or cut meals often' item and 141 (7%) for the 'hungry' item. Item-score correlations ranged from 0.444 to 0.580. Cronbach's alpha was 0.77. Relative item severities from the Rasch model ranged from -1.622 (standard error 0.043) for the 'balanced meal' item to 1.103 (0.068) for the 'skipped or cut meals often' item and 0.944 (0.062) for the 'hungry' item. The 'hungry' item gave a slightly lower relative severity in boys than girls. Food insecurity was associated with household overcrowding (adjusted odds ratio comparing highest and lowest quartiles 2.61, 95% confidence interval 1.75 to 3.91), lack of pipe-borne water in the home, low paternal education or paternal unemployment. After adjusting for socio-economic variables, food insecurity was associated with less frequent consumption of fruit (0.75, 0.60 to 0.94) or fish (0.72, 0.58 to 0.88) but more frequent consumption of biscuits or cakes (1.47, 1.02 to 2.11). CONCLUSIONS: The food security scale provides a valid, reliable measure in adolescents, although young people report being hungry but not eating relatively more frequently than adults. Food-insecure adolescents have low socio-economic position and may eat less healthy diets.

Reliability and validity of a short form household food security scale in a Caribbean community.

BACKGROUND: We evaluated the reliability and validity of the short form household food security scale in a different setting from the one in which it was developed. METHODS: The scale was interview administered to 531 subjects from 286 households in north central Trinidad in Trinidad and Tobago, West Indies. We evaluated the six items by fitting item response theory models to estimate item thresholds, estimating agreement among respondents in the same households and estimating the slope index of income-related inequality (SII) after adjusting for age, sex and ethnicity. RESULTS: Item-score correlations ranged from 0.52 to 0.79 and Cronbach's alpha was 0.87. Item responses gave within-household correlation coefficients ranging from 0.70 to 0.78. Estimated item thresholds (standard errors) from the Rasch model ranged from -2.027 (0.063) for the 'balanced meal' item to 2.251 (0.116) for the 'hungry' item. The 'balanced meal' item had the lowest threshold in each ethnic group even though there was evidence of differential functioning for this item by ethnicity. Relative thresholds of other items were generally consistent with US data. Estimation of the SII, comparing those at the bottom with those at the top of the income scale, gave relative odds for an affirmative response of 3.77 (95% confidence interval 1.40 to 10.2) for the lowest severity item, and 20.8 (2.67 to 162.5) for highest severity item. Food insecurity was associated with reduced consumption of green vegetables after additionally adjusting for income and education (0.52, 0.28 to 0.96). CONCLUSIONS: The household food security scale gives reliable and valid responses in this setting. Differing relative item thresholds compared with US data do not require alteration to the cut-points for classification of 'food insecurity without hunger' or 'food insecurity with hunger'. The data provide further evidence that re-evaluation of the 'balanced meal' item is required.

Reliability and validity of a short form household food security scale in a Caribbean community

BACKGROUND: We evaluated the reliability and validity of the short form household food security scale in a different setting from the one in which it was developed. METHODS: The scale was interview administered to 531 subjects from 286 households in north central Trinidad in Trinidad and Tobago, West Indies. We evaluated the six items by fitting item response theory models to estimate item thresholds, estimating agreement among respondents in the same households and estimating the slope index of income-related inequality (SII) after adjusting for age, sex and ethnicity. RESULTS: Item-score correlations ranged from 0.52 to 0.79 and Cronbach's alpha was 0.87. Item responses gave within-household correlation coefficients ranging from 0.70 to 0.78. Estimated item thresholds (standard errors) from the Rasch model ranged from -2.027 (0.063) for the 'balanced meal' item to 2.251 (0.116) for the 'hungry' item. The 'balanced meal' item had the lowest threshold in each ethnic group even though there was evidence of differential functioning for this item by ethnicity. Relative thresholds of other items were generally consistent with US data. Estimation of the SII, comparing those at the bottom with those at the top of the income scale, gave relative odds for an affirmative response of 3.77 (95% confidence interval 1.40 to 10.2) for the lowest severity item, and 20.8 (2.67 to 162.5) for highest severity item. Food insecurity was associated with reduced consumption of green vegetables after additionally adjusting for income and education (0.52, 0.28 to 0.96). CONCLUSIONS: The household food security scale gives reliable and valid responses in this setting. Differing relative item thresholds compared with US data do not require alteration to the cut-points for classification of 'food insecurity without hunger' or 'food insecurity with hunger'. The data provide further evidence that re-evaluation of the 'balanced meal' item is required.

Food insecurity, food choices, and body mass index in adults: nutrition transition in Trinidad and Tobago.

BACKGROUND: This study evaluated whether food insecurity and obesity were associated in a population sample in Trinidad. METHODS: A sample was drawn of 15 clusters of households, in north central Trinidad. Resident adults were enumerated. A questionnaire was administered including the short form Household Food Security Scale (HFSS). Heights and weights were measured. Analyses were adjusted for age, sex, and ethnic group. RESULTS: Data were analysed for 531/631 (84%) of eligible respondents including 241 men and 290 women with a mean age of 47 (range 24-89) years. Overall, 134 (25%) of subjects were classified as food insecure. Food insecurity was associated with lower household incomes and physical disability. Food insecure subjects were less likely to eat fruit (food insecure 40%, food secure 55%; adjusted odds ratio [OR] = 0.60, 95% CI: 0.36-0.99, P = 0.045) or green vegetables or salads (food insecure 28%, food secure 51%; adjusted OR = 0.46, 95% CI: 0.27-0.79, P = 0.005) on >/=5-6 days per week. Body mass index (BMI) was available for 467 (74%) subjects of whom 41 (9%) had BMI <20 kg/m(2), 157 (34%) had BMI 25-29 kg/m(2), and 120 (26%) had BMI >/=30 kg/m(2). Underweight (OR = 3.21, 95% CI: 1.17-8.81) was associated with food insecurity, but obesity was not (OR = 1.08, 95% CI: 0.55-2.12). CONCLUSIONS: Food insecurity was frequent at all levels of BMI and was associated with lower consumption of fruit and vegetables. Food insecurity was associated with underweight but not with present obesity.

Food insecurity definitions and body mass index. Response

In his commentary, Dr Edward A. Frongillo criticizes our use of a well-described household food security scale in Trinidad. There will always be some uncertainty concerning the application of a given measure as there is no perfect instrument to evaluate food security or dietary patterns in any population. The household food security measure was used in the US national Current Population Survey (which provided the comparison data used in Dr Frongillo's commentary) but the application of the instrument to all groups in the multilingual, culturally diverse US population 'has not been examined sufficiently' (ref. 3, p. 8). Questionnaire evaluation must be considered when differences in literacy, language, dialect, or culture, as well as socioeconomic status, may influence responses and this consideration might suggest that an instrument should be tailored to local requirements. It is advisable, however, to be judicious in modifying such measures so as not to compromise the validity or comparability of an instrument. Departures from a previously tested template should only be undertaken to guarantee enhanced performance of a measure. Dr Frongillo's comments appear to underestimate both the weight of evidence required to justify an alteration to an established measure and the limitations of local 'validation' studies. Before concluding that a measure gives unsatisfactory results in a given local population, or a particular group within a population, it is essential to ensure that the findings cannot be ascribed to error or bias. There is a relatively high risk that local questionnaire evaluation studies, implemented within the short time scales suggested, will lead to erroneous conclusions if sample sizes are too small or if subjects are insufficiently representative.

Food insecurity, food choices, and body mass index in adults: nutrition transition in Trinidad and Tobago

BACKGROUND: This study evaluated whether food insecurity and obesity were associated in a population sample in Trinidad. METHODS: A sample was drawn of 15 clusters of households, in north central Trinidad. Resident adults were enumerated. A questionnaire was administered including the short form Household Food Security Scale (HFSS). Heights and weights were measured. Analyses were adjusted for age, sex, and ethnic group. RESULTS: Data were analysed for 531/631 (84%) of eligible respondents including 241 men and 290 women with a mean age of 47 (range 24-89) years. Overall, 134 (25%) of subjects were classified as food insecure. Food insecurity was associated with lower household incomes and physical disability. Food insecure subjects were less likely to eat fruit (food insecure 40%, food secure 55%; adjusted odds ratio [OR] = 0.60, 95% CI: 0.36-0.99, P = 0.045) or green vegetables or salads (food insecure 28%, food secure 51%; adjusted OR = 0.46, 95% CI: 0.27-0.79, P = 0.005) on >/=5-6 days per week. Body mass index (BMI) was available for 467 (74%) subjects of whom 41 (9%) had BMI <20 kg/m(2), 157 (34%) had BMI 25-29 kg/m(2), and 120 (26%) had BMI >/=30 kg/m(2). Underweight (OR = 3.21, 95% CI: 1.17-8.81) was associated with food insecurity, but obesity was not (OR = 1.08, 95% CI: 0.55-2.12). CONCLUSIONS: Food insecurity was frequent at all levels of BMI and was associated with lower consumption of fruit and vegetables. Food insecurity was associated with underweight but not with present obesity.