The national and regional trends in anemia in Chad are presented for 2016–2021, excluding 2020 when hemoglobin assessments were not collected due to COVID-19. Risk factors for anemia, including IYCF indicators, are explored for the most recent available data, including 2019 and 2021.

Trends in anemia, 2016–2021

Anemia status was determined from hemoglobin values available from 5,771 to 9,109 children aged 6 to 59 months and 5,214 to 7,198 women 15 to 49 years of age, with variation in the sample size by year. The national prevalence of anemia in children declined from 68.6% to 2016 to 59.6% in 2021 (p < 0.001) (Fig. 2 and Supplementary Tables 1, Additional File 1). The Sudanian zone consistently had the highest prevalence of child anemia from 2016 (78.1%) to 2021 (64.1%), with rates exceeding 80% in the provinces of Logone Occidental, Mandoul, and Mayo Kebi Ouest in 2018 or 2019 (Supplementary Tables 2, Additional File 1). In the Sahelian zone, the prevalence decreased steadily from 65.4% to 2016 to 56.3% in 2021 (p < 0.001). N’Djamena also saw a slight decrease in prevalence of anemia from 56.9% to 2016 to 51.1% in 2021, but this was not statistically significant (p = 0.113). In contrast, between 2016 and 2021 the prevalence in the Saharan zone increased from 48.7 to 56.8% (p = 0.001), with high variability in province-level rates in 2018 and 2019.

Fig. 2

Trends in anemia prevalence in children under five and women of reproductive age by agroecological zone in Chad, 2016–2021

The national prevalence of women’s anemia declined significantly from 47.6% to 2016 to 30.8% in 2021 (p < 0.001), with the greatest decreases occurring from 2019 to 2021 (Fig. 2). The Saharan zone had the lowest rates of anemia in women, similar to what was observed for children, and experienced the most significant decline over the six-year period, from 38.2% to 2016 to 17.2% in 2021 (p < 0.001) (Supplementary Tables 1, Additional File 1). The Sahelian and Sudanian zones had the highest rates in the country, where over half the provinces exceeded a prevalence of 50% in 2016, followed by a general decline in 2017, and a resurgence of rates over 50% in several provinces in 2018 and 2019 (Supplementary Tables 3, Additional File 1). However, the two zones had an overall significant decline from 2016 to 2021, from 48.7 to 30.8% (p < 0.001) in the Sahelian zone and 49.9–38.6% (p < 0.001) in the Sudanian zone. In N’Djamena, the anemia prevalence decreased from 37.2% to 2016 to 28.9% in 2021, (p = 0.012).

Characteristics of children, women, and households in 2019 and 2021

Data were available for 5,879 and 6,636 children 6–59 months of age in 2019 and 2021, respectively. Across both years, age and sex were normally distributed (Table 1). IYCF indicators were lower in 2019 compared to 2021, with 50.6% and 65.3% of children 6–23 months achieving MMF, 7.9% and 12.6% achieving MDD, and 4.7% and 9.3% achieving MAD, respectively (Table 2). Among women of reproductive age, data were available for 5,527 and 6,033 women in 2019 and 2021, respectively. Across both years, age was normally distributed and almost half of women were non-pregnant and non-lactating (49.5% and 49.0%), about a third were lactating only (35.4% and 34.1%), less than a fifth were pregnant only (14.5% and 15.7%), and few were both pregnant and lactating (0.7% and 1.3%) (Table 3). In both years, approximately a fifth (18.0% and 22.9%) of women received nutrition counseling in the previous three months, a quarter reported some knowledge of women’s nutrition (25.2% and 22.9%), and less than 7% reported knowledge of anemia prevention.

Table 1 Risk factors for anemia in children under-five in Chad, 2019 and 2021 Table 2 IYCF indicators and odds of anemia among children 6–23 months in Chad in 2019 and 2021 Table 3 Risk factors for women’s anemia in Chad in 2019 and 2021

Household characteristics of the sampled children and women in 2019 and 2021 are presented in Tables 1 and 3, respectively, and the distributions are similar. Most households were male headed (72.3–78.6%) and the majority were married (89.2–94.0%). Approximately half of household heads were illiterate (46.0-51.5%) and the most common primary income source was farming (56.0-64.5%). About half of households resided in the Sahelian zone, less than one-third in the Sudanian zone, ~ 15% in the Saharan zone, and ~ 5% in N’Djamena.

Determinants of anemia in children 6–59 months of age, 2019 and 2021

In both years, there was a linear relationship between age and the odds of anemia, whereby younger children had greater odds of being anemic than older children (Table 1). In 2019, children under 24 months were over three times as likely to be anemic compared to children 48–60 months after adjusting for other variables (6–12 months AOR: 3.50, 95%CI: 2.83, 4.33; 12–24 months AOR:3.05, 95%CI: 2.56, 3.64). In 2021, children 6–12 and 12–24 months were 5.20 times (95%CI: 4.26, 6.37) and 4.55 times (95%CI:3.86, 5.38) as likely to be anemic compared to children 48–60 months even after adjusting for other significant variables. Child sex, marital status and sex of the head of the household were not significantly associated with child anemia in 2019 or 2021. In 2019 and 2021, children had significantly lower odds of anemia with a head of household who reported being literate compared to illiterate; in adjusted models, this finding remained significant only in 2019 (AOR: 0.76, CI: 0.67, 0.88). In 2019, children of pastoralists had lower odds of anemia, (AOR: 0.76 95%CI: 0.59, 0.98), whereas in 2021, children of business/transport workers (AOR: 0.81 95%CI: 0.69, 0.96), civil servants (AOR: 0.67 95%CI: 0.51, 0.89), and temporary workers (AOR: 0.67 95%CI: 0.51, 0.89) had lower odds of anemia compared to children of farmers.

Agroecological zone was significantly associated with child anemia in 2019 and 2021, though to varying degrees. In the 2019 adjusted models, the odds ratio for children in the Sudanian zone was 2.86 (95%CI: 2.31, 3.54), making them almost three times as likely to be anemic compared to children in the Saharan zone. Children in the Sahelian zone also had a significantly higher likelihood of having anemia, with an odds ratio of 1.32 (95%CI: 1.05, 1.49). In 2021, after adjusting for the other significant variables, children in the Sudanian zone were still more likely to have anemia than children in the Saharan zone but differences were less pronounced (AOR: 1.51, 95%CI:1.24, 1.84). The odds of anemia in the Sahelian zone were not significantly different from the Saharan zone in 2021 and N’Djamena rates were similar to the Saharan zone both years.

IYCF and the relationship to anemia among children 6–23 months of age, 2019 and 2021

The relationship between consumption of select food groups and anemia in children differed in 2019 and 2021 (Table 2). In 2019, children who consumed vitamin A rich foods exhibited higher odds of anemia, but this relationship was non-significant in the adjusted model (AOR: 1.24, 95%CI: 0.95, 1.63). In 2021, children who consumed vitamin A rich foods had significantly lower odds of anemia than children who did not (AOR: 0.67, 95%CI: 0.53, 0.84). Consumption of meat products was not associated with anemia in 2019 but was associated with reduced odds of anemia in 2021 (AOR: 0.72, 95%CI: 0.58, 0.88). Consumption of dairy/eggs was not associated with reduced odds of anemia after adjusting for individual and household factors. In both 2019 and 2021, achieving MDD was associated with 35% reduced odds of anemia in the adjusted models (95%CI: 0.46, 0.92; 95%CI: 0.50, 0.86). In 2021, children who achieved MMF or MAD also had significantly reduced odds of anemia (AOR: 0.49, 95%CI: 0.38, 0.63; AOR: 0.64, 95%CI: 0.47, 0.89) compared to children who did not. However, in 2019, MMF and MAD were not associated with the odds of anemia after adjusting for other significant variables.

Table 4 presents the odds ratio of anemia in children by agroecological zone, both unadjusted and adjusted for MDD, MMF, and MAD independently. In 2019, the unadjusted odds of anemia were 1.32 times and 2.77 times greater in the Sahelian and Sudanian zones as compared to the Saharan zone. These were not attenuated by the addition of any one of the three IYCF indicators, and the AORs between agroecological zone and anemia remained similar. In N’Djamena, the addition of any of the IYCF variables identified a more acute relationship, whereby the odds of anemia were about twice as high in the capital than in the Saharan zone, as compared to the unadjusted OR of 1.29 (95%CI: 0.95, 1.74). In 2021, a different pattern was observed where the addition of any one of the IYCF indicators to the model appeared to mediate the relationship between agroecological zone and anemia, specifically in the Sudanian context. With the addition of MDD, MMF, or MAD in the models, the odds of anemia went from 1.54 (95%CI: 1.31, 1.80) to 1.04–1.25, all non-significant.

Table 4 Odds of anemia by agroecological zone after adjusting for child diet among children 6–23 months in Chad, 2019–2021 Determinants of women’s anemia in 2019 and 2021

Differences were observed in the factors associated with the odds of anemia in women in 2019 and 2021 (Table 3). In 2019, women’s receipt of nutrition counseling in the last 3 months was associated with reduced odds of anemia in the unadjusted and adjusted models (AOR: 0.68, 95%CI: 0.59, 0.79), but this was not seen in 2021. PLW status was not associated with anemia in 2019, but in 2021, women who were both pregnant and lactating had reduced odds of anemia compared to those NPNL (AOR: 0.31, 95%CI: 0.16, 0.61), though the sample size was small (n = 80). In 2021, women who reported knowledge of women’s nutrition had reduced odds of anemia (AOR: 0.78, 95%CI: 0.69, 0.89), but the same was not true for those that reported specific knowledge of anemia prevention (OR: 0.86, 95%CI: 0.69, 1.07). Report of any nutrition knowledge was not associated with anemia in 2019. Age was not associated with anemia in either year.

In both years, women who lived in a household where the head of household was literate had lower odds of anemia compared to illiterate household heads (AOR: 0.75–0.81). Women living in households where the primary income source was farming had greater odds of anemia than any of the other occupations, though not always significant. In 2019, households with income sources from business/transport, civil service, and no employment had significantly lower odds of anemia in women after adjusting for other variables, compared to farmers. In 2021, business/transport, temporary work, and the unemployed were less likely to have anemia than those working as farmers (Table 3). Marital status and sex of head of household were not associated with women’s anemia.

In both 2019 and 2021, agroecological zone was a significant predictor of women’s anemia. Women living in the Sudanian zone were 2.41 (95%CI: 2.00, 2.94) and 3.16 (95%CI: 2.57, 3.89) times more likely to have anemia as compared to women living in the Saharan zone in 2019 and 2021, respectively. In 2019, women living in the Sahelian zone and N’Djamena also experienced 1.80 (95% CI: 1.52, 2.14) and 1.46 (95%CI: 1.07, 1.98) times greater odds of anemia compared to those in the Sahara, after adjusting for other significant variables. The same trend was found in 2021, with even greater odds ratios between any of the other regions and the Saharan zone (Table 3).