Secular change in the association between urbanisation and abdominal adiposity in China (1993-2011)

Background Little attention has been paid to how the association between urbanisation and abdominal adiposity changes over the course of economic development in low-income and middle-income countries. Methods Data came from the China Health and Nutrition Survey waves 1993-2011 (seven waves). A mixed linear model was used to investigate the association between community-level urbanisation with waist-to-height ratio (WHtR; an indicator of abdominal adiposity). We incorporated interaction terms between urbanisation and study waves to understand how the association changed over time. The analyses were stratified by age (children vs adults). Results Adult WHtR was positively associated with urbanisation in earlier waves but became inversely associated over time. More specifically, a 1 SD increase in the urbanisation index was associated with higher WHtR by 0.002 and 0.005 in waves 1993 and 1997, while it was associated with lower WHtR by 0.001 in 2011. Among child participants, the increase in WHtR over time was predominantly observed in more urbanised communities. Conclusion Our study suggests a shift in adult abdominal adiposity from more urbanised communities to less urbanised communities over a time of rapid economic development in China. Children living in more urbanised communities had higher increase in abdominal obesity with urbanisation over time relative to children living in less urbanised communities.