Measuring socio-economic position in dietary research: is choice of socio-economic indicator important?

Abstract

Objectives: To examine the association between socio-economic position (SEP) and diet, by assessing the unadjusted and simultaneously adjusted (independent) contributions of education, occupation and household income to food purchasing behaviour. Design: The sample was randomly selected using a stratified two-stage cluster design, and the response rate was 66.4%. Data were collected by face-to-face interview. Food purchasing was examined on the basis of three composite indices that reflected a household's choice of grocery items (including meat and chicken), fruit and vegetables. Setting: Brisbane City, Australia, 2000. Participants: Non-institutionalised residents of private dwellings ðn ¼ 1003Þ; located in 50 small areas (Census Collectors Districts). Results: When shopping, respondents in lower socio-economic groups were less likely to purchase grocery foods that were high in fibre and low in fat, salt and sugar. Disadvantaged groups purchased fewer types of fresh fruits and vegetables, and less often, than their counterparts from more advantaged backgrounds. When the relationship between SEP and food purchasing was examined using each indicator separately, education and household income made an unadjusted contribution to purchasing behaviour for all three food indices; however, occupation was significantly related only with the purchase of grocery foods. When education and occupation were simultaneously adjusted for each other, the socio-economic patterning with food purchase remained largely unchanged, although the strength of the associations was attenuated. When household income was introduced into the analysis, the association between education, occupation and food purchasing behaviour was diminished or became non-significant; income, however, showed a strong, graded association with food choice. Conclusions: The food purchasing behaviours of socio-economically disadvantaged groups were least in accord with dietary guideline recommendations, and hence are more consistent with greater risk for the development of diet-related disease. The use of separate indicators for education, occupation and household income each adds something unique to our understanding of how socio-economic position is related to diet: each indicator reflects a different underlying social process and hence they are not interchangeable, and do not serve as adequate proxies for one another.

Multiple socio-economic circumstances and healthy food habits

“…This, in turn, may result to differences in healthy food habits by economic situation. Similar findings have been reported in Australia, where food purchasing behaviours among the socio-economically disadvantaged were least in accordance with dietary recommendations (Turrell et al, 2003a). In France, the costs of more nutrient-dense, healthier diets have been found to be higher, whereas energy-dense diets high in fat and sugar continue to be a low-cost option (Drewnowski et al, 2004;Andrieu et al, 2006).…”

“…Thus, examining the associations of several indicators with food habits contributes to a better understanding of the production of socio-economic differences in food behaviours. Furthermore, each socio-economic indicator has been suggested to reflect different underlying social processes (Lynch and Kaplan, 2000;Turrell et al, 2003a). The importance of using various indicators from different stages of the life course has also been recently highlighted (Galobardes et al, 2006a, b).…”

Neighborhood disadvantage, individual‐level socioeconomic position, and self‐reported chronic arthritis: A cross‐sectional multilevel study

“…Also, our finding of an association between neighborhood disadvantage and self-reported arthritis might be confounded by individual-level socioeconomic factors not included in the models. However, we included 3 of the most widely used indicators of an individual's socioeconomic characteristics (education, occupation, and income), and given the correlation among these measures (40), it is likely that these socioeconomic indicators are capturing some of the unmeasured influences of other socioeconomic factors not included in the models. Alternatively, it may be that the inclusion of individual-level measures of SES resulted in "overadjustment," which provides evidence for the possibility of an even stronger contextual effect on self-reported arthritis than was observed in this study.…”

Assessing social differences in overweight among 15- to 16-year-old ethnic Norwegians from Oslo by register data and adolescent self-reported measures of socio-economic status

“…9 Although these measures are usually correlated, independent effects on dietary habits have been shown. 10,11 Parson et al 8 present two models that may explain the association between low SES and greater fatness in studies of adults: low SES may promote development of fatness or greater fatness may lead to downward social mobility. Sobal and Stunkard 7 argue that weight control and pressure for thinness is more common among women of high SES than women of low SES, but state that little is known about why this is so.…”