The effect of rural-to-urban migration on risk factors of cardiovascular diseases in Bangladesh

Abstract

Background/Aim: Cardiovascular disease (CVD) has been emerging as an important public health problem in Bangladesh. The underlying cause of this epidemic is the increase in life expectancy accompanied by demographic transition and changing lifestyles as a result of urbanization. Bangladesh has been experiencing rapid urbanization for the past several decades, which is mostly driven by migration from rural area. Hence, it is vital to more fully understand the effect of rural-to-urban migration on CVD risk factors. Methods: A secondary data analysis on nationally representative Urban Health Survey (UHS) data collected in Bangladesh followed by an empirical sibling-pair comparative study were conducted to identify the effect of migration on CVD risk factors, and the role of socioeconomic status (SES) and the impact of acculturation indicators on CVD risk. In the UHS study 27,792 participants were included in the analyses of whom 14,167 (M: 7278; W: 6889) were urban residents and 13,625 (M: 6413; W: 7212) were rural-to-urban migrants. The sibling-pair comparative study was conducted on 164 males migrated from Pirganj rural areas to Dhaka City and had been residing in Dhaka permanently for at least one year, and their rural siblings (total N =328). Participants were undergone interview particularly on diet, physical activity and other behavioural risk factors; measurement on anthropometric and blood pressure; and biochemical analysis of blood for blood glucose level and lipid profile. Besides, three validity studies on physical activity and dietary tools were conducted on 162 healthy participants of both genders aged 18-60 years from rural (n=97) and urban (n=65) areas to be used in sibling study as well as future CVD risk factors surveillance in Bangladesh. Results: In the UHS study, the risk profile of migrant was lower than the risk profile of the urban group for most of the CVD risk factors (overweight and obesity, hypertension, diabetes, smoking) except bidi smoking and mental health disorder, which were higher in rural-to-urban migrants. The risk profile of CVD differed in men and women and women migrants were more vulnerable than any other groups in terms of metabolic risk factors and mental health disorders. Using the rural group as baseline, the sibling-pair comparative study demonstrates that the risk profile of migrant group was higher in all CVD risk factors. Migration was associated with an increased physical inactivity and reduced fruits and vegetable and poly unsaturated fatty acid (PUFA) intake in migrants, as compared with rural siblings, and this likely contributed to the higher levels of body mass index (BMI), skinfold thickness and lower high density lipoprotein (HDL) in migrants. The findings of both studies suggest that CVD risk factors increase with time spent in urban area, though the pattern and magnitude of these changes were not uniform and varied across risk factors and gender. In the UHS study, consistent increasing pattern of risk was observed with longer duration of urban stay in migrant men for obesity (OR=1.67), smoking (OR=1.67) and alcohol intake (OR=2.86). Among women, those with a longer period living in an urban area had 74% and 35% higher odds of being classified as overweight and obese, and with mental health disorder, respectively. In the sibling-pair comparative study, the strongest effects were seen with increasing duration of urban stay for the three primary outcome measures: low HDL (OR=6.53), inadequate fruit and vegetable intake (OR=4.83) and physical inactivity (OR=3.63). The UHS study demonstrated that the proportion of CVD risk factors among migrants were also varied by urban place of residence. Hypertension as well as overweight and obesity were more prevalent in non-slum than slum, whereas mental health disorder, cigarette and bidi smoking were higher in slum and District Municipalities than non-slum. In the validity study, physical activity and dietary tools showed acceptable validity and therefore were used in the sibling study. Conclusion: The overall findings of this thesis suggests that migration from rural to urban area is a risk for CVD. This risk increase with time spent in urban area due to acculturation and varied by urban place of residence. The studies give new insights into the increased CVD risk related with migration and urbanization in Bangladesh.

Date of Award	2018
Original language	English