Socio-demographic determinants of obesity indexes in Iran:findings from a nationwide STEPS survey

Introduction

Overweight and obesity are the major risk factors for non-communicable diseases (NCDs) such as type 2 diabetes mellitus (T2DM), elevated blood pressure (BP), cardiovascular diseases (CVDs), some cancers and musculoskeletal disorders.¹ According to World Health Organization’s (WHO’s) report, 1.9 billion of adults ≥18 years were overweight and over 600 million were obese in 2014²and by the year 2030, 2.16 billion people are expected to be overweight and 1.12 billion obese.³ Along with other countries in the world, obesity is considered as one of the most important public health threats in Asian countries, including Iran.⁴‏ Over an 8-year period (1999-2007), the prevalence of overweight and obesity among Iranian adults has increased significantly.⁵ Iran is one of the developing countries that has experienced social and economic transition, cultural changes and urbanization conditions⁶ which can affect the prevalence of NCDs and their risk factors including overweight and obesity.⁷ The main indicators of obesity are body mass index (BMI), abdominal obesity which is assessed using the waist circumference (WC) and waist-hip ratio (WHR).³ Studies showed these indicators are associated with NCDs morbidity and mortality such as CVDS and T2DM.^8-10 Thus, one the aims of Global Action Plan for the Prevention and Control of Non-Communicable Diseases 2013-2020 by WHO is to stop obesity by 2025.¹¹

Epidemiological studies showed that socio-demographic characteristics and namely lifestyles of individuals in any region are among the most important determinants of overweight and obesity.³ Therefore, determining the distribution of socio-demographic determinants of overweight and obesity can be helpful in designing actions plans to promote a healthy lifestyle and prevention and control of overweight and obesity. The WHO STEPwise approach to surveillance (STEPS) for NCDs risk factors is a WHO’s recommended approach to determine public health priorities as a baseline for healthy interventions through determining prevalence of risk factors for NCDs such as biological and modifiable behavioral risk factors by standardized STEPS instrument for standard data collection.¹² This nationwide study aimed to determine socio-demographic determinants of obesity indexes as the risk factors for NCDs in Iran.

Materials and Methods

Results

Discussion

According to WHO’s report, 39% of adults ≥18 years old were overweight and 13% were obese in 2014.² Considering our findings, the prevalence of overweight in our study was lower than global rate while it was vice versa for obesity prevalence.

In the first nationwide survey of overweight and obesity prevalence among Iranian adults (2004-2005), the age-adjusted means for BMI was 24.6 in men and 26.5 kg/m² in women.⁷ Considering the results of this study, the mean of BMI in both sexes slightly increased in this time period. In addition, according to the Global Health Observatory (GHO) data by WHO, the mean BMI (age-standardized estimate) among over 18 male and female Iranians in 2014 were 25.3 [24.6-25.9] and 27.0 [26.4-27.7], respectively. The results of our study is very close to this report.¹⁴

In addition, our data showed that several socio-demographic characteristics were associated positively or negatively with overweight and obesity. Similar to the results of most studies^15-17 overweight was more common among men while the reverse was the case for prevalence of obesity and the rate of obesity was higher in women than men. In our study abdominal obesity was more prevalent in women than men though in most similar studies this rate was higher in men than women.^6,7,9,18 However, each region of any country has a different pattern of prevalence for overweight and obesity due to sociocultural issues differences. In the most studies in Iran, physical inactivity has been identified as the main cause of higher prevalence of obesity in women than men.^4,6 On the other hand, it should be noted that obesity prevention particularly in women is more important because overweight and obesity can expose women to gestational problems and birth complications.¹⁹

In terms of age group, participants aged ≤60 years had BMI, WC and WHR above normal in our study. Of course, in different studies, these rates among different age groups were more prevalent but the positive realtionship between these rates with older age has been confirmed in all of them.^{3,4,7,14,15,20,21} Our findings showed that the level of education is a essential determinant for overweight and obesity so that in our study overweight/obsity was more prevalent in people with lower level of education. A negative association of overweight and obesity with level of education attained has been proven in other similar studies.^3,4,14,20,21 In a study on country–level data related to overweight prevalence in 192 countries from 2002, 2005, and 2010, higher education level was posotively associated with overweight.²²

In terms of occupation status, overweight/obesity based on BMI and WHR above normal were higher among retired people than others and WC above normal was higher among housvife women than others. The higher prevalence rates in these two occupational groups are due to lower level of physical activity among these people than other occupations. Obesity indexes were also higher among alone people compared to others. These people were mostly the elderly and had low physical activity. In our study residence in urban areas was also a determinant for overweight and obesity. This finding that urbanization is a one of the main resons for obesity has been confimed in other similar studies in Iran and other countries.^{6,7,17,19,22,23} Higher prevalence of overweight/obesity among some ethnicity in this study is needed further studies to explore the causality of this association.

According to the our findings, among overweight and followed by obese participants and also participants with WC and WHR above normal, the history of elevated BP, CVDs and T2DM were significantly observed more than others. The mean of systolic and diastolic BP were higher among obese participants and those with WC and WHR sbove normal.

Since overweight and obesity are well-established as main risk factors for T2DM, elevated BP and following that CVDs,^24-26, the above mentioned findings highlight the necessity of planning and implementation of obesity prevention programs in our country.

Conclusion

Our study showed the growing prevalence of overweight and obesity as compared with previous studies in Iran, as well as other countries in the world. However, the prevalence of overweight in this study was less than global rate while it was vice versa for obesity prevalence. Socio-demographic conditions were identified as determinant factors of overweight and obesity. Some of these factors significantly influenced the prevalence of overweight and obesity in our study, including being female, older age, less than education level (especially illiteracy), being retired and housevife (due to physical inactivity), being alone and urbanization. Being obese or overweight was associated with having the history of T2DM, hypertension (HTN) and CVDs. Identifyong these factors can help health policy makers of our country to develop and implement preventive and control action plan considering these factors.

Ethical approval

The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki, and the Ethics Committee of Shahid Beheshti University of Medical Sciences under the ethics code IR.SBMU.RETECH.REC.1394.121 approved it. Researches considered all the principles of medical ethics, including the consent of the participants, the confidentiality of personal data and free measurements.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

All authors contributed to this work, including study concept and design, analysis and interpretation of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content, statistical analysis, administrative, technical, and material support and study supervision. All authors read and approved the final manuscript.

Acknowledgments

This study has been funded and supported by Shahid Beheshti University of Medical Sciences. The study was a medical student’s thesis.

References

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