Educational inequality in the occurrence of abdominal obesity:Pró-Saúde Study

Ronaldo Fernandes Santos Alves Eduardo Faerstein About the authors

Abstracts

OBJECTIVE

To estimate the degree of educational inequality in the occurrence of abdominal obesity in a population of non-faculty civil servants at university campi.

METHODS

In this cross-sectional study, we used data from 3,117 subjects of both genders aged 24 to 65-years old, regarding the baseline ofPró-Saúde Study, 1999-2001. Abdominal obesity was defined according to abdominal circumference thresholds of 88 cm for women and 102 cm for men. A multi-dimensional, self-administered questionnaire was used to evaluate education levels and demographic variables. Slope and relative indices of inequality, and Chi-squared test for linear trend were used in the data analysis. All analyses were stratified by genders, and the indices of inequality were standardized by age.

RESULTS

Abdominal obesity was the most prevalent among women (43.5%; 95%CI 41.2;45.9), as compared to men (24.3%; 95%CI 22.1;26.7), in all educational strata and age ranges. The association between education levels and abdominal obesity was an inverse one among women (p < 0.001); it was not statistically significant among men (p = 0.436). The educational inequality regarding abdominal obesity in the female population, in absolute terms (slope index of inequality), was 24.0% (95%CI 15.5;32.6). In relative terms (relative index of inequality), it was 2.8 (95%CI 1.9;4.1), after the age adjustment.

CONCLUSIONS

Gender inequality in the prevalence of abdominal obesity increases with older age and lower education. The slope and relative indices of inequality summarize the strictly monotonous trend between education levels and abdominal obesity, and it described educational inequality regarding abdominal obesity among women. Such indices provide relevant quantitative estimates for monitoring abdominal obesity and dealing with health inequalities.

Obesity; Abdominal; epidemiology; Socioeconomic Factors; Health Status Disparities; Gender and Health


INTRODUCTION

Obesity is an important global public health problem, with rising trends in several development contexts.2828 .World Health Organization. Obesity: preventing and managing the global epidemic: report of a WHO Consultation. Geneva; 2000. (WHO Technical Report Series, 894). Obese people have increased risks of adverse outcomes in the long run, and that even holds true for people with no metabolic abnormalities, as compared to individuals of normal weight and metabolically healthy.1717 .Kramer CK, Zinman B, Retnakaran R. Are metabolically healthy overweight and obesity benign conditions?: a systematic review and meta-analysis. Ann Intern Med. 2013;159(11):758-69. DOI:10.7326/0003-4819-159-11-201312030-00008 In Brazil, around 50.0% of the adult population is overweight, and 15.0% of it is obese.aa Instituto Brasileiro de Geografia e Estatística. Pesquisa de Orçamentos Familiares 2008-2009: antropometria e estado nutricional de crianças, adolescentes e adultos no Brasil. Rio de Janeiro (RJ); 2010 [cited 2014 Jan 10]. Available from: http://www.ibge.gov.br/home/estatistica/populacao/condicaodevida/pof/2008_2009_encaa/pof_20082009_encaa.pdf

According to the World Health Organization, obesity regards to abnormal or excessive body fat accumulation.2828 .World Health Organization. Obesity: preventing and managing the global epidemic: report of a WHO Consultation. Geneva; 2000. (WHO Technical Report Series, 894). Even though body mass index has been the classic anthropometric measurement in population studies, abdominal circumference has been observed to have better predictive abilities for certain obesity-related morbidities.2929 .World Health Organization. Waist circumference and waist-hip ratio: report of a WHO expert consultation. Geneva; 2011. Besides that, as it measures abdominal obesity, it is a key element in the definition of metabolic syndrome1919 .Lim S, Meigs JB. Ectopic fat and cardiometabolic and vascular risk.Int J Cardiol. 2013;169(3):166-76. DOI:10.1016/j.ijcard.2013.08.077 and in the analysis of risks for cardiovascular diseases, diabetes, cancer, and death.4.Després JP, Lemieux I, Prud’homme D. Treatment of obesity: need to focus on high risk abdominally obese patients. BMJ. 2001;322(7288):716-20. DOI:10.1136/bmj.322.7288.716,2424 .Neamat-Allah J, Wald D, Hüsing A, Teucher B, Wendt A, Delorme S, et al. Validation of anthropometric indices of adiposity against whole-body magnetic resonance imaging: a study within the German European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts. PLoS One. 2014;9(3):e91586. DOI:10.1371/journal.pone.0091586. eCollection 2014

The relationship between socioeconomic position and obesity is consistent, but it is observed to have variations according to genders and levels of economic development.5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001,2323 .Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult population of developing countries: a review. Bull World Health Organ. 2004;82(12):940-6. DOI:10.1590/S0042-96862004001200011 In low-income countries, a higher probability for obesity is observed among groups of high socioeconomic positions in both genders. In medium and high-income countries, the association between socioeconomic position and obesity is frequently shown to be inverse among women, especially regarding education, whereas it is observed to be both direct and not statistically significant among men. Those changes in the association pattern between socioeconomic position and obesity take place in early economic development stages, thus revealing the importance of studies and preventive interventions in that context.5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,7.Ezzati M, Vander Hoorn S, Lawes CMM, Leach R, James WPT, Lopez AD, et al. Rethinking the “disease of affluence” paradigm: global patterns of nutritional risk in relation to economic development. PLoS Med. 2005;2(5):e133. DOI:10.1371/journal.pmed.0020133,2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001,2323 .Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult population of developing countries: a review. Bull World Health Organ. 2004;82(12):940-6. DOI:10.1590/S0042-96862004001200011

Measures which are based on the contrasts between comparison groups are commonly used analytic strategies to report the extent and direction of the association between socioeconomic position and obesity. However, they have the simultaneous interpretation of different partial inequality estimates as a disadvantage, as polytomous variables are often used as socioeconomic position indicators.3030 .World Health Organization. Handbook on health inequality monitoring: with a special focus on low- and middle-income countries. Geneva; 2013. Alternate methods have been proposed to measure and monitor health-related socioeconomic inequalities, considering only one quantitative estimate of inequalities;1414 .Harper S, Lynch J. Methods for measuring cancer disparities: using data relevant to Health People 2010 cancer-related objectives. Bethesda: National Cancer Institute; 2005.,3030 .World Health Organization. Handbook on health inequality monitoring: with a special focus on low- and middle-income countries. Geneva; 2013. however, they are not very disseminated in the epidemiological practice.

Even though the relationship between socioeconomic position and obesity is well documented in the epidemiological literature, its association with abdominal obesity, especially, is not yet very understood. Furthermore, no publications were found reporting socioeconomic inequality regarding abdominal obesity in adults in Brazil. Exploring the inequality regarding abdominal obesity may be important to enhance actions to prevent obesity and its consequences. This study intended to estimate the degree of educational inequality in the occurrence of abdominal obesity in a population of non-faculty civil servants at university campi.

METHODS

In this cross-sectional study, we used data from Pró-Saúde Study baseline (EPS1999-2001). EPS is a longitudinal investigation program of non-faculty civil servants at a university campi in Rio de Janeiro, Southeastern Brazil, mainly focusing on social determinants of health.9.Faerstein E, Chor D, Lopes CS, Werneck GL. Estudo Pró-Saúde: características gerais e aspectos metodológicos. Rev Bras Epidemiol. 2005;8(4):454-66. DOI:10.1590/S1415-790X2005000400014 So far, four data collection stages were conducted (1999, 2001, 2006, and 2012) by trained teams comprising field researchers, supervisors, and coordinators. The EPS baseline was simultaneously composed of eligible subjects in the first two stages.

We included all employees in the permanent staff of the university who accepted to take part in stages 1 and 2 (baseline) of EPS. Pregnant women and people older than 65 years of age were excluded. A pilot study, pre-testing of research instruments and procedures, independent entering of data by two professionals, and monitoring of the collection and data processing ensure the quality of analyzed information.8.Faerstein E, Lopes CS, Valente K, Solé-Plá MA, Ferreira MB. Pré-testes de um questionário multidimensional autopreenchível: a experiência do Estudo Pró-Saúde UERJ. Physis Rev Saude Coletiva. 1999;9(2):117-30. DOI:10.1590/S0103-73311999000200007,9.Faerstein E, Chor D, Lopes CS, Werneck GL. Estudo Pró-Saúde: características gerais e aspectos metodológicos. Rev Bras Epidemiol. 2005;8(4):454-66. DOI:10.1590/S1415-790X2005000400014 Covariates were obtained from 1999 census; independent and dependent variables, from 2001 census.

The concentration of fat in the abdominal region was evaluated by a double measurement of abdominal circumference at the level of the navel, through the use of a 180-meter measuring tape. Subjects, in order to be taken measurements, kept their arms folded over their chests, their feet close together, their weights equally distributed between their legs, their abdomens relaxed, and their breathing at regular paces. Abdominal obesity was defined according to abdominal circumference thresholds of 88 cm for women and 102 cm for men, as suggested by the World Health Organization.2929 .World Health Organization. Waist circumference and waist-hip ratio: report of a WHO expert consultation. Geneva; 2011.

A multidimensional, self-administered questionnaire was used to collect the information on genders (male, female), age in years (24 to 34, 35 to 44, 45 to 54, 55 to 65), and education levels (incomplete elementary education, complete elementary education, incomplete high school education, complete high school education, incomplete university education, complete university education, graduate studies).

Preliminary statistical analyses included: absolute and relative frequencies, prevalence of abdominal obesity, and respective 95% confidence intervals and Chi-squared test for the linear trend among ordinal variables and dichotomous outcome. Slope (SII) and relative (RII) indices of inequality were used to estimate the degree of educational inequality in the occurrence of abdominal obesity. Those indices may produce absolute and relative estimates of the socioeconomic gradient in health, and they are based on weighted regression analysis.1414 .Harper S, Lynch J. Methods for measuring cancer disparities: using data relevant to Health People 2010 cancer-related objectives. Bethesda: National Cancer Institute; 2005.,3030 .World Health Organization. Handbook on health inequality monitoring: with a special focus on low- and middle-income countries. Geneva; 2013. Linear and logistic regression was used to respectively calculate SII and RII, as well as the respective 95% confidence intervals. The dependent variable was abdominal obesity (dichotomous). The independent variable was a numerical score that was defined from the median of the cumulative interval in each category of the social polytomous variable in the horizontal scale of the population (Table 1). Thus, instead of attributing ordinal values (e.g., 1, 2, 3,..., k, for a series of k categories) to subjects from the respective educational categories, numerical values were attributed – they considered: (a) the information from all simultaneously ordered categories; (b) the proportional size of those categories; and (c) their relative positions within the population scale. Finally, such numerical values were employed in the related regression models by the numerical score. SII and RII were standardized by ages.

Table 1
Frequency measurements used in the algebraic proposition of the numerical score.

Below is an algebraic proposition to clarify the numerical score. In Table 1, a logic arrangement of used frequency measurements is shown in matrix format, in order to support reading of the numerical score formulation.

Score 1: 0 + [Fr1 – 0] ÷ 2 = (F1 ÷ N) ÷ 2 = (f1/N) ÷ 2

Score 2: Fr1 + [(Fr2 – Fr1) ÷ 2] = F1/N + [(F2/N – F1/N) ÷ 2]

= f1/N + {[(f1 + f2 – f1)/N)] ÷ 2]}

= f1/N + [(f2/N) ÷ 2]

= f1/N + (f2/2N)

= [(f1 + f2/2) ÷ N]

Score 3: Fr2 + [(Fr3 – Fr2) ÷ 2] = F2/N + [(F3/N – F2/N) ÷ 2]

= F2/N + {[(F2 + f3 – F2)/N)] ÷ 2]}

= (f1 + f2)/N + [(f3/N) ÷ 2]

= (f1 + f2)/N + (f3/2N)

= [(f1 + f2 + f3/2) ÷ N]

Hence,

Score k: [(f1 + f2 + f3 + f4 + ... + fk/2) ÷ N]

= [(Fk - 1 + fk/2) ÷ N]

All analyses were stratified by genders and processed in R 3.1.0 software.

The EPS 1999 and 2001 protocols were approved by the Research Ethics Committee of Pedro Ernesto University Hospital, of Universidade do Estado do Rio de Janeiro (Record 224/1999; Record 461/2001). All subjects signed informed consent forms. Data were analyzed in a way to ensure subjects total anonymity.

RESULTS

The study population comprised subjects who were eligible in the two first stages of EPS 1999 and 2001. During field work, 9.6% of subjects skipped participation in stage 1 – and 16.5% in stage two, which totaled 3,253 subjects in both stages (77.9% of eligible ones), who regard to the baseline of the investigation program. The abdominal perimeters of 52 people could not be measured (1.6%); 21 subjects (0.7%) were excluded the data analysis as they were older than 65 years; 63 subjects (1.9%) did not answer the question regarding education level variable. Finally, a sample of 3,117 adults was obtained (95.8% of subjects).

The women in the sample slightly outnumbered the men (Table 2). The average age was 42.7 (95%CI 42.3;43.1) years for women and 41.2 (95%CI 40.8;41.6) for men. The women were observed to have high educational levels, and 47.0% of them had at least finished university, whereas for men, a share of 36.0% was observed regarding that. The average age was higher in the categories with the lowest education levels, ranging from 53 to 40 years among women, and from 48 to 50 years among men.

Table 2
Sociodemographic characteristics in Pró-Saúde Study baseline, 1999-2001.

The prevalence of abdominal obesity in the baseline population of EPS was 35.0% (95%CI 33.3;36.7). It was significantly higher among women (43.5%; 95%CI 41.2;45.9) as compared to men (24.3%; 95%CI 22.1;26.7), in all educational strata and age ranges (Table 3). Among the women, the probability for being obese increased with the age, and it was notably higher in the group of 55 to 65-year olds (73.0%; 95%CI 65.2;79,9). Decreased prevalence of abdominal obesity was observed among 55 to 65-year old men, but the small population size of that subgroup may have influenced that specific estimate.

Table 3
Prevalence (%) of abdominal obesity, slope index of inequality, and relative index of inequality of the female population.Pró-Saúde Study, 1999-2001.

The education levels were shown to be consistent and inversely associated with abdominal obesity among women, but not among men. Important differences were especially noted among the categories with the same educational attainment. Prevalence of abdominal obesity was higher among women with complete elementary education (67.8%; 95%CI 57.1;77.2) than the one from women with incomplete high school education (54.5%; 95%CI 45.6;63.2). Higher prevalence was found among the women with complete high school education (50.3%; 95%CI 57.1;77.2) than the one from women with incomplete university education (42.5%; 95%CI 45.6;63.2). In the male population, Chi-squared test for linear trend did not rule out the null hypothesis for homogeneity among educational categories (p = 0.436).

SII and RII were only applied to the female population, which is information implying linearity between the polytomous social factor and the health-related outcome.1414 .Harper S, Lynch J. Methods for measuring cancer disparities: using data relevant to Health People 2010 cancer-related objectives. Bethesda: National Cancer Institute; 2005.,1616 .Keppel K, Pamuk E, Lynch J, Carter-Pokras O, Kim I, Mays V, et al. Methodological issues in measuring health disparities. Vital Health Stat Series 2. 2005;(141):1-16.,3030 .World Health Organization. Handbook on health inequality monitoring: with a special focus on low- and middle-income countries. Geneva; 2013. In this sense, the indices of inequality provided a quantitative synthesis of the strictly monotonous trend that is observed between education levels and abdominal obesity (Figure). The numerical score considered the female population as a whole, by making the estimates for inequality regarding abdominal obesity sensitive to population size variations in educational subgroups at different times.

Figure
Educational inequality regarding abdominal obesity among multiple educational groups in the female population. Pró-SaúdeStudy, 1999-2001.

The analyses indicated that the consistent and inverse relationship between education levels and abdominal obesity was influenced by the ages; however, it was observed to keep a noticeable pattern (Table 3). The absolute and relative degree of inequality regarding abdominal obesity among multiple educational groups was, respectively, 24.0% (SII; 95%CI 15.5;32.6) and 2.8 (RII; 95%CI 1.9;4.1), after the age adjustment.

The indices of inequality are cross-sectionally correlated in time,1616 .Keppel K, Pamuk E, Lynch J, Carter-Pokras O, Kim I, Mays V, et al. Methodological issues in measuring health disparities. Vital Health Stat Series 2. 2005;(141):1-16. pointing towards the same conclusion about inequality: the probability for being obese was “gradually” higher among the women of lower education levels. However, those indices may describe contradicting results in regards to the degree and direction of educational inequality regarding abdominal obesity throughout time, which comes to highlight the importance of using both measurements.2.Barros AJD, Victora CG. Measuring coverage in MNCH: determining and interpreting inequalities in coverage of maternal, newborn, and child health interventions. PLoS Med. 2013;10:e1001390. DOI:10.1371/journal.pmed.1001390,1414 .Harper S, Lynch J. Methods for measuring cancer disparities: using data relevant to Health People 2010 cancer-related objectives. Bethesda: National Cancer Institute; 2005.

DISCUSSION

The baseline population of EPS was observed to have a high prevalence of abdominal obesity, with an important difference when genders are compared. It was higher among women in all educational strata and age ranges. Gender inequality in the prevalence of abdominal obesity increases with older age and lower education levels, given its steeper direct association with older age in the female population, its inverse one with education levels among women, and not statistically significant association among the men. SII and RII summarized a uniform trend between education levels and abdominal obesity, and they described educational inequality in the occurrence of abdominal obesity among women.

Excess intra-abdominal fat has been particularly important to understand the consequences of obesity. Hypertrophy and hyperplasia of visceral adipocytes increase the risk of hypertriglyceridemia, insulin resistance, and atherosclerosis, regardless of body compositions.1919 .Lim S, Meigs JB. Ectopic fat and cardiometabolic and vascular risk.Int J Cardiol. 2013;169(3):166-76. DOI:10.1016/j.ijcard.2013.08.077In this sense, abdominal circumference has been observed to have a higher correlation with visceral adipose tissue, as compared to other anthropometric assessments for abdominal adiposity,4.Després JP, Lemieux I, Prud’homme D. Treatment of obesity: need to focus on high risk abdominally obese patients. BMJ. 2001;322(7288):716-20. DOI:10.1136/bmj.322.7288.716,2424 .Neamat-Allah J, Wald D, Hüsing A, Teucher B, Wendt A, Delorme S, et al. Validation of anthropometric indices of adiposity against whole-body magnetic resonance imaging: a study within the German European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts. PLoS One. 2014;9(3):e91586. DOI:10.1371/journal.pone.0091586. eCollection 2014 being shown to be more informational when based on an underlying biological argument. Nevertheless, differences regarding measuring techniques and thresholds may influence estimates for prevalence and association with abdominal obesity. A limitation in this study regards to measuring abdominal circumference at the navel level, once the employed thresholds concern measurement at the midpoint between the last rib and the iliac crest.2929 .World Health Organization. Waist circumference and waist-hip ratio: report of a WHO expert consultation. Geneva; 2011.

Socioeconomic position is a complex and multidimensional construct, in which individuals are classified by being compared to other individuals, based on material and non-material attributes.1818 .Krieger N, Williams DR, Moss NE. Measuring social class in US public health research: concepts, methodologies, and guidelines. Annu Rev Public Health. 1997;18:341-78. DOI:10.1146/annurev.publhealth.18.1.341Frequently used socioeconomic position indicators: education, occupation, and income – each with its advantages and constraints.1111 .Galobardes B, Shaw M, Lawlor DA, Lynch JW, Smith GD. Indicators of socioeconomic position (part 1). J Epidemio l Community Health. 2006;60(1):7-12. DOI:10.1136/jech.2004.023531,1818 .Krieger N, Williams DR, Moss NE. Measuring social class in US public health research: concepts, methodologies, and guidelines. Annu Rev Public Health. 1997;18:341-78. DOI:10.1146/annurev.publhealth.18.1.341 Even though they concern different epidemiological aspects, such indicators have generally pointed towards the same direction in the association with obesity.1.Ball K, Crawford D. Socioeconomic status and weight change in adults: a review. Soc Sci Med. 2005;60(9):1987-2010. DOI:10.1016/j.socscimed.2004.08.056,5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001 Notwithstanding, education represents the assets regarding the knowledge of a person,1111 .Galobardes B, Shaw M, Lawlor DA, Lynch JW, Smith GD. Indicators of socioeconomic position (part 1). J Epidemio l Community Health. 2006;60(1):7-12. DOI:10.1136/jech.2004.023531 which assumedly influence ways of living and life styles linked to obesity,2626 .Sobal J. Obesity and socioeconomic status: a framework for examining relationships between physical and social variables. Med Anthropol. 1991;13(3):231-47. DOI:10.1080/01459740.1991.9966050 and they also determine other socioeconomic position attributes, such as occupation and income.1111 .Galobardes B, Shaw M, Lawlor DA, Lynch JW, Smith GD. Indicators of socioeconomic position (part 1). J Epidemio l Community Health. 2006;60(1):7-12. DOI:10.1136/jech.2004.023531,1818 .Krieger N, Williams DR, Moss NE. Measuring social class in US public health research: concepts, methodologies, and guidelines. Annu Rev Public Health. 1997;18:341-78. DOI:10.1146/annurev.publhealth.18.1.341

Frequent ways to operationalize education include years of schooling and education attainment. The continuous measurement assumes that each year of schooling similarly contributes to the socioeconomic position, and the categorical measurement assumes that formal education attainment are more relevant for the socioeconomic position than the time one spends with education.1111 .Galobardes B, Shaw M, Lawlor DA, Lynch JW, Smith GD. Indicators of socioeconomic position (part 1). J Epidemio l Community Health. 2006;60(1):7-12. DOI:10.1136/jech.2004.023531

This study considered intermediate levels within a same educational attainment, based on the hypothesis that more time spent with education is relatively important for the association between socioeconomic position and abdominal obesity, which depends on the educational attainment that was reached. That distinction was shown to be important in the distribution of female abdominal obesity in the variation spectrum of education levels.

The indices of inequality provided information that was opportune for longitudinal analyses regarding EPS, as well as for meta-analysis studies and comparisons of the degree of educational inequalities regarding abdominal obesity among populations, geographical areas, and health indicators.1616 .Keppel K, Pamuk E, Lynch J, Carter-Pokras O, Kim I, Mays V, et al. Methodological issues in measuring health disparities. Vital Health Stat Series 2. 2005;(141):1-16. Furthermore, ascribing ordinal values to the categories of polytomous variables may produce quantitatively meaningless dosage-response curves, especially when those categories are internally heterogeneous.1313 .Greenland S. Analysis of polytomous exposures and outcomes. In: Rothman KJ, Greenland S, Lash TL, editors. Modern epidemiolgy. 3.ed. Philadelphia: Lippincott Williams and Wilkins; 2008. p.303-27.

The findings in this research are shown to be in agreement with different cross-sectional and longitudinal studies in distinct populations.1.Ball K, Crawford D. Socioeconomic status and weight change in adults: a review. Soc Sci Med. 2005;60(9):1987-2010. DOI:10.1016/j.socscimed.2004.08.056,5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001,2323 .Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult population of developing countries: a review. Bull World Health Organ. 2004;82(12):940-6. DOI:10.1590/S0042-96862004001200011 From early socioeconomic development stages, the association between socioeconomic position and obesity becomes predominantly inverse among women, but not among men.5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001,2323 .Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult population of developing countries: a review. Bull World Health Organ. 2004;82(12):940-6. DOI:10.1590/S0042-96862004001200011 In Brazil, time series analyses showed increased prevalence and incidence of obesity, which is associated with lower education only in the female population,3.Conde WL, Borges C. O risco de incidência e persistência de obesidade entre adultos brasileiros segundo seu estado nutricional ao final da adolescência. Rev Bras Epidemiol. 2011;14 Supl 1:71-9. DOI:10.1590/S1415-790X2011000500008,1212 .Gigante DP, França GVA, Sardinha LMV, Iser BPM, Meléndez GV. Variação temporal na prevalência do excesso de peso e obesidade em adultos: Brasil, 2006 a 2009. Rev Bras Epidemiol. 2011;14 Supl 1:157-65. DOI:10.1590/S1415-790X2011000500016 mainly in urban contexts and the most developed regions in the country.2222 .Monteiro CA, Conde WL, Popkin BM. Independent effects of income and education on the risk of obesity in the Brazilian adult population. J Nutr. 2001;13(3):881S-886S.,aa Instituto Brasileiro de Geografia e Estatística. Pesquisa de Orçamentos Familiares 2008-2009: antropometria e estado nutricional de crianças, adolescentes e adultos no Brasil. Rio de Janeiro (RJ); 2010 [cited 2014 Jan 10]. Available from: http://www.ibge.gov.br/home/estatistica/populacao/condicaodevida/pof/2008_2009_encaa/pof_20082009_encaa.pdf A particularly consistent and inverse association between female socioeconomic position and abdominal obesity was found in population-based studies in Rio de Janeiro,1515 .Kac G, Velásquez-Meléndez G, Coelho MASC. Fatores associados à obesidade abdominal em mulheres em idade reprodutiva. Rev Saude Publica. 2001;35(1):46-51. DOI:10.1590/S0034-89102001000100007 Minas Gerais,1010 .Freitas SN, Caiaffa WT, César CC, Faria VA, Nascimento RM, Coelho GLLM. Risco nutricional na população urbana de Ouro Preto, sudeste do Brasil: estudo de corações de Ouro Preto. Arq Bras Cardiol. 2007;88(2):191-9. DOI:10.1590/S0066-782X2007000200010 Rio Grande do Sul,2020 .Linhares RS, Horta BL, Gigante DP, Dias-da-Costa JS, Olinto MTA. Distribuição de obesidade geral e abdominal em adultos de uma cidade no sul do Brasil. Cad Saude Publica. 2012;28(3):438-48. DOI:10.1590/S0102-311X2012000300004 and Maranhao,2727 .Veloso HJF, Silva AAM. Prevalência e fatores associados à obesidade abdominal e ao excesso de peso em adultos maranhenses. Rev Bras Epidemiol. 2010;13(3):400-12. DOI:10.1590/S1415-790X2010000300004 especially regarding education, which thus reinforces the proposition of social determination of general and abdominal obesity.

Socioeconomic position influences the individual access to goods and services regarding nutrition, physical activity, and other healthy practices,2626 .Sobal J. Obesity and socioeconomic status: a framework for examining relationships between physical and social variables. Med Anthropol. 1991;13(3):231-47. DOI:10.1080/01459740.1991.9966050 as well as environmental conditions which may influence the association between socioeconomic position and abdominal obesity. Groups of higher socioeconomic position tend to eat most nutritious foods, at least partly due to their buying those foods more easily.6.Drewnowski A. Obesity, diets, and social inequalities. Nutr Rev. 2009;67 Suppl 1:S36-9. DOI:10.1111/j.1753-4887.2009.00157.x They also have higher access to weight-losing methods than groups of lower socioeconomic position.2525 .Salles-Costa R, Werneck GL, Lopes CS, Faerstein E. Associação entre fatores sócio-demográficos e prática de atividade física de lazer no Estudo Pró-Saúde. Cad Saude Publica. 2003;19(4):1095-105. DOI:10.1590/S0102-311X2003000400031 Besides that, socioeconomic position may cause an impact in attitudes towards one’s own body and in weight-losing practices, especially among women of higher socioeconomic position. They may be more inclined to making efforts towards leaner bodies, whereas obesogenic environments make it harder for women of lower socioeconomic position to do the same.2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001

Among men, the relationship between socioeconomic position and obesity is less clearly observed in medium and high-income contexts. Most studies report not statistically significant associations, the second most frequent result of them being the direct association with income and other indicators of material assets.5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001 Heavier bodies may be valued differently among genders, and they may represent force and domination for men of higher socioeconomic position.2121 .McLaren L. Socioeconomic status and obesity. Epidemiol Rev. 2007;29(1):29-48. DOI:10.1093/epirev/mxm001

A rising trend for obesity in association with low socioeconomic position among women in medium and high-income regions will increasingly drive relevant iniquities in different health conditions related to obesity.5.Dinsa GD, Goryakin Y, Fumagalli E, Suhrcke M. Obesity and socioeconomic status in developing countries: a systematic review. Obes Rev. 2012;13(11):1067-79. DOI:10.1111/j.1467-789X.2012.01017.x,7.Ezzati M, Vander Hoorn S, Lawes CMM, Leach R, James WPT, Lopez AD, et al. Rethinking the “disease of affluence” paradigm: global patterns of nutritional risk in relation to economic development. PLoS Med. 2005;2(5):e133. DOI:10.1371/journal.pmed.0020133,2323 .Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult population of developing countries: a review. Bull World Health Organ. 2004;82(12):940-6. DOI:10.1590/S0042-96862004001200011 According to Ezzati et al,7.Ezzati M, Vander Hoorn S, Lawes CMM, Leach R, James WPT, Lopez AD, et al. Rethinking the “disease of affluence” paradigm: global patterns of nutritional risk in relation to economic development. PLoS Med. 2005;2(5):e133. DOI:10.1371/journal.pmed.0020133 the ‘diseases of affluence’ paradigm must be reconsidered. According to Monteiro et al,2323 .Monteiro CA, Moura EC, Conde WL, Popkin BM. Socioeconomic status and obesity in adult population of developing countries: a review. Bull World Health Organ. 2004;82(12):940-6. DOI:10.1590/S0042-96862004001200011 food insecurity and high physical activity patterns became less common after a certain stage of economic development, even for more socially underprivileged segments.

The low percentage of non-respondents (< 5.0%) considerably contributed to the sample representativeness. Regarding the inferential scope, the results in this study do not support generalization to the general population, but they can properly reflect the current patterns in average urban layers of reasonable heterogeneity, as those are an economically active, regularly employed population. No important differences were found when the sociodemographic characteristics of the studied population were compared with the adult population of employed workers in the municipality of Rio de Janeiro.8.Faerstein E, Lopes CS, Valente K, Solé-Plá MA, Ferreira MB. Pré-testes de um questionário multidimensional autopreenchível: a experiência do Estudo Pró-Saúde UERJ. Physis Rev Saude Coletiva. 1999;9(2):117-30. DOI:10.1590/S0103-73311999000200007

So far, few studies aimed to examine the relationship between socioeconomic position and abdominal obesity, and not studies were found to describe the degree of educational inequality regarding abdominal obesity by applying indices of inequality in an adult population in Brazil. Potential mediators of that relationship, such as race/ethnicity, area of residence, birth-related cohort, parity, and marital status, need yet to be explored in order to better understand educational inequality regarding abdominal obesity. In conclusion, the indices of inequality provided quantitative estimates that are indispensable for the monitoring of abdominal obesity and for the drafting of public policies.

ACKNOWLEDGMENTS

To professors Célia Landmann Szwarcwald, PhD, Gulnar Azevedo e Silva, PhD, and to Yara Hahr Marques Hökerberg, PhD, for the important comments in the first draft of the manuscript. To the members of Pró-Saúde Study team for their strong dedication in the production of the data we used in our analyses.

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    Veloso HJF, Silva AAM. Prevalência e fatores associados à obesidade abdominal e ao excesso de peso em adultos maranhenses. Rev Bras Epidemiol 2010;13(3):400-12. DOI:10.1590/S1415-790X2010000300004
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  • a
    Instituto Brasileiro de Geografia e Estatística. Pesquisa de Orçamentos Familiares 2008-2009: antropometria e estado nutricional de crianças, adolescentes e adultos no Brasil. Rio de Janeiro (RJ); 2010 [cited 2014 Jan 10]. Available from: http://www.ibge.gov.br/home/estatistica/populacao/condicaodevida/pof/2008_2009_encaa/pof_20082009_encaa.pdf
  • Based on the master’s essay by Ronaldo Fernandes Santos Alves, titled: “Desigualdade socioeconômica e obesidade abdominal: uma apreciação crítica e pragmática em epidemiologia”, which was presented in the Graduate Program in Collective Health of the Instituto de Medicina Social of the Universidade do Rio de Janeiro, in 2014.
  • This study was presented at the 9th Edition of Brazilian Epidemiology Congress, in Vitória, Espírito Santo state, in 2014.
  • This study was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq – Process 484636/2013-8) and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ – Grade 10 research grant, Master's – Process 100,489/2013).

Publication Dates

  • Publication in this collection
    09 Oct 2015

History

  • Received
    6 Aug 2014
  • Accepted
    31 Jan 2015
Faculdade de Saúde Pública da Universidade de São Paulo São Paulo - SP - Brazil
E-mail: revsp@org.usp.br