8 Veghari

JRHS 2010; 10(2): 116-121

Copyright © Journal of Research in Health Sciences        

The Prevalence of Obesity and its Related Risk Factor in the North of Iran in 2006

Gholamreza Veghari (MSc)a*, Mehdi Sedaghat (MD)b, Hamidreza Joshaghani (PhD)c, Ahmad Hoseini (MD)b, Farhad Niknezhad (PhD)c, Abdolhamid Angizeh (BSc)b, Ebrahim Tazik (BSc)b, Pooneh  Moharloei (MD)b

a Golestan Cardiovascular Research Center, Department of Biochemistry and Nutrition, School of Medicine, Golstan University of Medical Sciences, Gorgan, Iran

b Deputy of Health Services, Golestan University of Medical Sciences, Gorgan, Iran

c Department of Laboratory Sciences, School of Paramedical and Health, Golestan University of Medical Sciences, Gorgan, Iran

Correspondence:Gholamreza Veghari (MSc), E-mail: grveghari@yahoo.com

Received: 28 September 2010, Revised: 3 November 2010, Accepted: 13 December 2010, Available online: 18 December 2010

Abstract                

Background: The main objective of this study was to evaluate the prevalence of the obesity and the related risk factors in the north of Iran.

Methods: This was a population-based cross-sectional study that enrolled 2495 subjects (1247 males and 1248 females) using stratified cluster sampling. Interviewers recorded the data using a multidimensional questionnaire including anthropometric indexes. Body mass index equal to or greater than 25 was considered as overweight and that of 30 and 40 as obese and pathologic obese respectively. SPSS 16.0 software was used for statistical data analysis.

Results: Mean age of the subjects was 39.2 [95% CI: 38.6, 39.8] yr. Mean body mass index was 25.3 [95% CI: 25.0, 25.6] kg/m2 for men and 27.5 [95% CI: 27.2, 27.9] kg/m2 for women. The prevalence rates of overweight, obesity and pathologic obesity were 29.9% (745/2495), 22.5% (561/2495) and 1.8% (44/2495) respectively. The prevalence of obesity was higher in urban residents than rural ones, 27.3% versus 18.9% respectively (P<0.001). The prevalence rates of obesity and pathologic obesity were much higher in women than men were, 30.3% versus 15.4% and 3.0% versus 0.6% respectively (P=0.001). The odds ratio estimate was 1.68 [95% CI: 1.40, 2.02] for urban area compared to rural area; 2.60 [95% CI: 2.14, 3.15] for females compared to males; 5.95 [95% CI: 3.54, 9.99] for married people compared to single people; 1.89 [95% CI: 1.44, 2.84] for age group of 55-65 years compared to age group of 15-24 years; 1.76 [95% CI: 1.17, 2.64] for illiterate people compared to those who had academic education; 1.98 [95% CI: 1.13, 2.49] for poor people compared to people with high economic level.

Conclusion: The prevalence of obesity and overweight is very high in the north of Iran, hence is a signal of serious health problem, and should be the focus of special attention.   

Keywords: Obesity, Adults, Socio demographic factors, Iran

Introduction

Obesity emerged as a health problem during the past century whereas the prevalence of obesity and numbers of people who are overweight increased rapidly recently in many countries 1.

The cause of obesity is complex and multi-factorial worldwide. There are various risk factors, which are responsible for the weight gain and obesity in human. Both the metabolic and behavioral factors such as leptin and life style can effect on overweight and obesity 2. Previous studies introduced obesity as a health problem in Iran 3. Regarding the adverse side effects of obesity which reduce the normal life-span, it seems necessary to conduct a survey to recognize the people at risk as well as the pre-existing risk factors responsible for this serious health problem.

The third national surveillance of risk factors of non-communicable disease in Iran 4 reported the overall prevalence of obesity up to 22.3%. This survey reported that obesity was much more common in females and urban residents. Due to the logistic limitation, no study was conducted yet on the obesity in the north of Iran. Therefore, the present study was planned and performed to determine the obesity status and its related risk factors in this area.

Methods

This was a population-based cross-sectional study conducted in 2006 in Golestan Province, the north of Iran. We enrolled 2495 subjects (1247 males and 1248 females) using stratified cluster sampling. In this study, 125 clusters of 20 people were randomly selected from 11 districts using family code of primary health center in rural areas and postal code in urban areas with equal proportion of age group and sex. From each district, one team had been trained to complete the questionnaire and measuring anthropometric indexes. The questionnaire included demographic characteristics, residential area, marital status, economic status, educational level, and physical activity.

All family members in blocks who were in 15-65 years age were included in the clusters. Pregnant women and those who were unwilling to participate in this survey were excluded from the study. Data on physical activity and socio-economic parameters were collected using a predefined questionnaire. Weight was measured with low clothing without shoes. Height was measured in standing upright position. Body mass index (BMI) was calculated as weight (kg) /height (m2). BMI of 25.0-29.9 kg/m2 was classified as overweight, BMI of 30.0 to 39.9 kg/m2 was classified as obese, and BMI equal to or greater than 40 kg/m2 was classified as pathologic obese 5.

The economic status was categorized based on the home ownership, number of the rooms in the house, owning of the private car, structure of the house, and the number of the family members specifying one score to each one. Accordingly, the economic status of study population was classified as low (1score), moderate (2-3 score), and high (4 score). Physical activity was categorized into five categories based on daily work and activity including no physical activities (without moving from a place to another place), low physical activity (activity that requires extension of the muscular-skeletal system and moving from a place to another place), moderate physical activity (activity that requires sometimes  increased respiratory rate like cleanliness, gardening, building painter, etc.), high physical activity (activity that requires very increased reparatory rate like manual labor, building labor, porter, etc.), and  very high activity (a combination of above activities) 6.

SPSS 16.0 software was used for the statistical analysis using chi-square test for comparing frequencies and t-test and ANOVA for comparing the means. Logistic regression analysis was applied in order to estimate the odds ratio (OR) of obesity considering the socio-demographic factors at 95% significant level.

Results

Mean age of the subjects was 39.2 [95% CI: 38.6, 39.8] yr. About 53.5% of subjects were living in rural area. The results of anthropometric measurements are shown in Table 1. The prevalence rates of overweight, obesity, and pathologic obesity were 30.34%, 22.48%, and 1.76%, respectively. The prevalence of overweight, obesity was higher in urban areas compared to rural areas, in women than men, and among married people compared to  single people (P<0.001).

Pearsons correlation coefficient showed a positive correlation between BMI and age (r=0.271, P=0.01) and BMI and economic status (r=0.061, P=0.01). Pearsons correlation coefficient was negative for BMI and physical activity (r=-0.065, P=0.01) and for BMI and education level (r= -0.143, P=0.01). Linear regression analysis revealed that BMI increases 0.271 unit for one year increase in age (P=0.001) (Table 1).

Table 1: The distribution of BMI based on demographic characteristics and lifestyle-related factors in the north of Iran

Characteristics

Level

N

Mean (95% CI)

P-value

BMI (kg/m2 )

<18.5

N (%)

18.5-24.9

N (%)

25-29.9

N (%)

30-39.9

N (%)

40

N (%)

P-value

Gender

Men

1247

25.3 (25.0, 25.6)

0.001

64 (5.2)

568 (46.0)

407 (32.9)

190 (15.4)

7 (0.6)

0.001

Women

1248

27.5 (27.2, 27.9)

54 (4.4)

413 (33.7)

350 (28.6)

371 (30.3)

37 (3.0)

Age group

15-25

499

22.8 (22.3, 23.4)

0.001

60 (12.2)

314 (63.7)

94 (19.1)

23 (4.7)

2 (0.4)

0.001

25-35

499

26.1 (25.5, 26.5)

18 (3.7)

209 (42.6)

157 (32.0)

102 (20.8)

5 (1.0)

35-45

499

27.7 (27.0, 28.2)

11 (2.2)

166 (33.5)

156 (31.5)

146 (29.5)

16 (3.2)

45-55

498

28.4 (27.7, 29.0)

13 (2.7)

130 (26.6)

157 (32.1)

177 (36.2)

12 (2.5)

55-65

500

27.1 (26.5, 27.7)

16 (3.2)

162 (32.9)

193(39.1)

113(22.9)

9(1.8)

Region

Urban

1161

27. 7 (26.9, 27.6)

0.001

39 (3.4)

397 (34.6)

370 (32.3)

313 (27.3)

28 (2.4)

0.001

Rural

1334

25.7 (24.4, 26.0)

79 (6.0)

584 (44.4)

387 (29.5)

248 (18.9)

16 (1.2)

Marital status

Married

1965

27.3 (26.9, 27.5)

0.001

55 (3.0)

618 (33.6)

637 (34.7)

494 (26.9)

34 (1.8)

0.001

Single

531

23.1 (22.5, 23.6)

58 (11.0)

329 (62.5)

96 (18.3)

40 (7.6)

3 (0.6)

Economic status

Poor

264

25.6 (26.1, 27.2)

0.008

13 (5.0)

118 (45.4)

85 (32.7)

41 (15.8)

3 (1.2)

0.041

Moderate

2144

26.5 (25.9, 26.6)

104 (4.9)

834 (39.4)

642 (30.3)

497 (23.5)

39 (1.8)

Good

87

27.7 (26.2, 28.1)

1 (1.2)

29 (34.1)

30 (35.3)

23 (27.1)

2 (2.4)

Educational level

Illiterate

740

27.3 (27.1, 28.0)

0.001

26 (3.6)

248 (34.2)

235 (32.4)

198 (27.3)

19 (2.6)

0.004

Diploma

1606

25.9 (25.7, 26.2)

91 (5.7)

673 (42.4)

459 (28.9)

340 (21.4)

24 (1.5)

Academic

149

26.2 (25.5, 26.9)

1 (0.7)

60 (40.5)

63 (42.6)

23 (15.5)

1 (0.7)

Physical activity

Low

637

26.9 (26.4, 27.4)

0.034

28 (4.5)

229 (36.5)

196 (31.2)

158 (25.2)

17 (2.7)

0.192

Moderate

1077

26.3 (25.9, 26.7)

62 (5.8)

433 (40.7)

319 (30.0)

235 (22.1)

16 (1.5)

Severe

104

25.7 (24.8, 26.6)

4 (4.0)

48 (47.5)

29 (28.7)

19 (18.8)

1 (1.0)

Combine

125

25.6 (24.7, 26.6)

5 (4.0)

57 (45.6)

40 (32.0)

22 (17.6)

1 (0.8)

Total

-

2495

26.4 (26.2, 26.7)


118 (4.7)

981 (39.3)

757 (30.3)

561 (22.5)

44 (1.8)

-


Multiple logistic regressions were used to identify variables that contribute to obesity. The odds ratio estimate was 1.68 [95% CI: 1.40, 2.02] for urban area compared to rural area; 2.60 [95% CI: 2.14, 3.15] for females compared to males; 5.95 [95% CI: 3.54, 9.99] for married people compared to single people; 1.89 [95% CI: 1.44, 2.84] for age group of 55-65 yr compared to age group of 15-24 yr; 1.76 [95% CI: 1.17, 2.64] for illiterate people compared to those who have academic education; 1.98 [95% CI: 1.13, 2.49] for poor people compared to people with high economic level (Table 2).

Table 2: The results of multiple logistic regression analysis of association between obesity (BMI30 kg/m2) and its related risk factors among adults population in the north of Iran

Risk factor

Level

OR (95% CI)

P value

Gender

Men (Ref)

1.00

0.001


Women

2.60 (2.14, 3.15)

Age group (year)

15-25 (Ref) 

1.00



25-35

0.16 (0.10, 0.26)

0.001


35-45

0.83 (0.62, 1.12)

0.228


45-55

1.47 (1.12, 1.94)

0.006


55-65

1.89 (1.44, 2.84)

0.001

Residential area 

Rural (Ref )

1.00



Urban

1.68 (1.40, 2.02)

0.001

Marital status

Single (Ref)

1.00



Married

5.95 (3.54, 10.0)

0.001

Economic status

Good (Ref)

1.00



Moderate

1.20 (0.75, 1.93)

0.453


Poor

1.98 (1.13, 3.50)

0.017

Educational level

College (Ref)  

1.00



Illiterate

1.76 (1.17, 2.67)

0.006


Primary to high school

1.51 (0.96, 2.38)

0.074

Physical activity

Combine (Ref)

1.00



Low

0.60 (0.37, 0.97)

0.037


Moderate

0.75 (0.47, 1.20)

0.229


Severe

0.95 (0.49, 1.84)

0.873

 

Discussion

The prevalence rates of overweight; obesity and pathologic obesity were 30.3%, 22.5%, and 1.8%, respectively. The prevalence of obesity and overweight reported 18.1% and 32.0% for Iranian general population respectively 7. In another study 8, the prevalence of overweight, obesity, and pathologic obesity among adults was reported 28.6%, 10.8%, and 3.4% respectively. A third study 9 estimated the prevalence of overweight and obesity 34.2% and 28% respectively. Two studies which were conducted in Babol County, the north of Iran reported the prevalence of overweight and obesity 22.7% and 18.8% respectively 10, 11.

The prevalence and pattern of obesity vary substantially between countries. The prevalence rate of obesity ranges from as low as 5% in China, Japan, and some region in Africa to as high as 75% in urban Samoa. However, even in countries where the overall prevalence of obesity is relatively low, such as China, the prevalence of obesity is almost 20% in some cities 12. Obesity is common in countries with high economical states like New Zealand, USA, and Australia. Obesity is also common in Arabic countries that consuming oil-rich nutrition like United Arab Emirates, Saudi Arabia and Kuwait. The prevalence of obesity is 23.5% in the USA 13; 40.6% in Spain 14; 18% in Irish 15; and 32.8% in Brazil 16.

According to the results of present study, overweight was more common in women than men. Furthermore,   the prevalence of obesity in women was two times more than that of men. This finding was confirmed by another study in Iran 8. Similar results are reported by the studies conducted in a number of Middle East countries. The prevalence of obesity is in women compared to men is 48.7% versus 21.2% in Bahrain 17; 26.6% versus 17.8% in Saudi Arabia 18; and 18.8% versus 14.3 in Lebanon 19. In the Eastern Mediterranean Region, the prevalence of obesity was higher in women (35%-75%) than men were (30%-60%) 20. A study reported that 27% of women and 35% of men in Canada have BMI equal to or greater than 27 21. The higher prevalence of obesity in women compared to men in our study can be explained by marital status in early age, especially in Turkmen ethnic group. This ethnic group live only in the north of Iran and their social behavior is very deferent from other ethnic groups. BMI is inversely related to sex hormone binding globulin concentration in women both in pre- and post-menopausal period 22.

We indicated that the prevalence of obesity and overweigh is significantly higher in urban area compared to rural area. Rashidi et al. 3 reported the prevalence of obesity 40% and 26% in urban and rural area respectively. Changing in lifestyle may lead to low physical activities in urban population compared to that of rural.

In our study, the pattern of obesity showed and increasing trend with age. Similar results were reported in other studies in Iran 23, 24.  In addition, age was considered as a predictor factor for obesity in some of studies 17-19, 25.

The association between socio-demographic factors and obesity that was shown in our study was also approved by other studies 26, 18-20. The association between low physical activity and obesity was shown in a study from Iran 23 as well as in other countries 27, 28. The inverse association between educational level and obesity has been approved in other studies in Iran 23, 28-29.

Conclusion

We concluded that prevalence rate of overweight and obesity was very high in the northern population of Iran. Urbanization, marriage, high economic status, illiteracy, and elderly are among the most common risk factors of obesity especially in women. Therefore, obesity is an important and common risk factor in northern population of Iran and should be focus of especial attention by policy makers those who plan educational programs.

Acknowledgments

The authors would like to thank the medical and administrative staff in the Primary Health Care Centers of Golestan University of Medical Sciences for their valuable assistance during the fieldwork.

Conflict of interest statement

The authors declare that they have no conflicts of interest.

Funding

This survey was supported by Health Office of Golestan University of Medical Sciences and justified for publication based on official document number 258888. 

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