Association of Anaemia and Anthropometric Indices Among Chinese Adults: Based on the Sixth China Chronic Disease and Risk Factor Surveillance

<b>Background</b>: Anaemia remains a widespread global public health concern. According to previous research reports, the prevalence rate of anaemia among Chinese adults is lacking. Additionally, the association between anaemia and four common anthropometric indices remains unclear. This study aimed to estimate the prevalence of anaemia and its association with anthropometric indices. <b>Methods</b>: The data was from a large, cross-sectional, nationally representative survey which was conducted from August 2018 to June 2019. A total of 190,236 individuals aged 18 years or old were invited, and 159,468 participants with complete data were included in this study. Anaemia was defined as the decrease in adjusted haemoglobin concentrations, <120 g/L for non-pregnant females and <130 g/L for males. Crude and weighted prevalence of anaemia in the overall population and different strata of Chinese adults were calculated. Weighted logistic regression and restricted cubic spline (RCS) were used to evaluate the association between anaemia and four anthropometric indices, including body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and body roundness index (BRI). <b>Results</b>: In China, the weighted anaemia prevalence was 9% (95% CI: 8.5-9.6%), 4.9% (95% CI: 4.4-5.4%), and 13.2% (95% CI: 12.4-13.9%) for the overall population, males, and females, respectively. The weighted prevalence of anaemia was higher among females, rural residents, southwestern residents, and individuals with primary-school-level or lower education than others. The prevalence was highest among young females (14.4%, 95% CI, 13.3-15.5%) and older males (11.8%, 95% CI, 12.4-14.3%). In the fully adjusted logistic regression model, per SD increase in BMI (OR = 0.96, 95% CI: 0.95-0.97), WC (OR = 0.99, 95% CI: 0.98-0.99), WHtR (OR = 0.15, 95% CI: 0.07-0.32), and BRI (OR = 0.90, 95% CI: 0.87-0.94) were associated with a decreased risk of anaemia. Furthermore, the RCS curves depicted L-shaped relationships between the study variables and anaemia (all <i>p</i> for nonlinear <0.05). <b>Conclusions</b>: The prevalence of anaemia among Chinese adults, especially among young females and underweight older adults, remained unexpectedly high. More attention should be paid to these populations.