Reassessing patterns of childhood body-mass index, overweight, and obesity in South Asian and black participants in the English National Child Measurement Programme: use of ethnicity-specific body-mass index adjustments

Abstract

BackgroundThe National Child Measurement Programme (NCMP) assesses patterns of overweight–obesity in English children. It uses body mass index (BMI), which overestimates body fatness in South Asian children and underestimates body fatness in black children of presumed African ethnicity. Using previously derived BMI adjustments, ensuring that adjusted BMI was similarly related to body fatness in South Asian, black, and white children, we reassessed population body fatness, overweight, and obesity patterns in these ethnic groups in the NCMP. MethodsAnalyses were based on 2012–13 NCMP data in 582 899 children aged 4–5 years and 485 362 children aged 10–11 years. Standard centile-based approaches defined weight status in each age-group before and after applying BMI adjustments, derived previously with the deuterium dilution method, for South Asian and black children. FindingsAmong white children, overweight–obesity prevalences were 23% (45 508/197 691) for boys and 21% (39 411/188 663) for girls in 4–5 year olds and 33% (52 635/160 278) and 30% (45 978/151 146), respectively, in 10–11 year olds. Before adjustment, South Asian children had lower overweight–obesity prevalences at 4–5 years (19% of boys [4485/23 191], 19% of girls [4176/22 109]; both p<0·0001) and higher prevalences at 10–11 years (42% of boys [8105/19 406], 34% of girls [6379/18 636]; both p<0·0001), whereas black children had higher overweight–obesity prevalences both at 4–5 years (31% of boys [4459/14 468], 29% of girls [4041/13 970]; both p<0·0001) and at 10–11 years (42% of boys [4788/11 347], 45% of girls [5048/11 319]; both p<0·0001). After adjustment, overweight–obesity prevalences were markedly higher in South Asian than in white children both at 4–5 years (39% of boys [9125/23 191], 35% of girls [7711/22 109]; both p<0·0001) and at 10–11 years (52% of boys [10 120/19 406], 44% of girls [8125/18 636]; both p<0·0001), whereas black children had a lower prevalence at 4–5 years (11% of boys [1526/14 468], 12% of girls [1700/13 970]; both p<0·0001); at 10–11 years, black boys had a slightly lower prevalence (32% [3619/11 347]; p=0·04) but girls a higher prevalence (35% [3937/11 319]; p<0·0001) than white children. InterpretationAdjusted BMI data reveal a substantial excess of overweight–obesity among English South Asian children (at 4–5 years and especially at 10–11 years) and among black girls (aged 10–11 years), with important implications for prevention. These patterns are not apparent with the use of unadjusted BMI data, which systematically underestimated overweight–obesity prevalences in South Asian children and overestimated them in black children. FundingBritish Heart Foundation, National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care (South London & North Thames).