The overall prevalence of IDA among the study participants was 44.5%. three -quarters (75.1%) of the anaemic participants it was due to iron deficiency. This can be attributed to the methods used in the diagnosis of IDA. This study employed a combination of red cell distribution width and microcytosis (on complete blood count and peripheral film) to derive the diagnosis. RDW is a simple and widely available test in routine haematological tests that measures the degree of the RBC size heterogenicity(29). It equally can express the smallest variation in red cell size which is accompanied by early iron deficiency unlike the other red cell indices (Mean corpuscular volume(MCV), Mean corpuscular haemoglobin (MCH) and Mean corpuscular haemoglobin concentration (MCHC))(30). There’s usually an overlap between patients with microcytic hypochromic anaemia in regards to red cell indices. This was observed in a study in Dhaka Shishu hospital where there was no significant difference between IDA and thalassemia in reference to MCV, MCH, and MCHC. A difference however was noted with RDW with statistically significance (P < 0.000)(31). RDW is a very sensitive measure that changes earliest in presence of iron deficiency anaemia even before microcytosis(2). Thus, it’s a sensitive measure in differentiating IDA from other causes of microcytic anaemia. (2, 32, 33). The peripheral film was considered as an earlier way for the microcytosis before CBC mean corpuscular volume changes are observed. This further gives an earlier diagnosis of microcytic anaemia(28, 34). It's thus a recommended test in absence of iron studies for the diagnosis of IDA(31). This could be one of the reasons why the study findings were lower than that observed in Lacor hospital, Uganda at 65.4%(26) and in Tanzania at 76% among children 6–23 months (35) where the diagnosis of IDA was based on peripheral film and Hb level respectively.
On another hand, the prevalence was higher than 17.7% in Eastern Uganda (24) and 21.1% in Entebbe (36). The higher prevalence is explained by the fact that the age category used in the current study is highly prone to IDA due to its rapid growth and accelerated nutrient demand(37). In addition, a wide age category was used compared to the Eastern Uganda study that enrolled children aged 11–23 months and both the studies used iron studies for the diagnosis of IDA which is a more specific test compared to RDW plus microcytosis. Unfortunately, iron studies are costly and not readily available. Furthermore, the high prevalence can be attributed to the fact that the age category used in the study is highly prone to IDA due to its rapid growth and accelerated nutrient demand in the growth spurt period(37). The study findings agree with other studies that IDA is the leading cause of anaemia among children (1, 2). This anaemia burden is still ranked as a severe public health concern(25) and thus an area of great concern to the public.
The majority of the study participants had mild-moderate anaemia 135 (89.4%) with the commonest being moderately anaemic 78 (51.7%) and only 16(10.6%) had severe anaemia. This is because mild to moderate IDA is asymptomatic and therefore those affected do not seek health attention. This agrees with a study in Korea where the prevalence was 36.9% (N = 491), 59.3% (N = 789), and 3.8% (N = 50) for mild, moderate, and severe anaemia respectively(38)
The study showed a significant association (P-value < 0.05) between IDA and sex, current episode of diarrhoea, less than acceptable meal frequency, and limited consumption of vegetables and fruits in the 7 days before the study.
Male infants had a more than 60% higher odds (AOR 1.61 (1.03–2.53) P 0.04) of having IDA compared to the females. This could be explained by the fact that compared to girls, boys have a relatively higher pre and post-natal growth rate but with low iron storage states due to observed larger intestinal iron loss, lower absorption, and more frequent infections (38–42). The study findings agree with a study in Finland where iron deficiency and IDA were more in boys compared to girls (19% vs. 9%)(43). It also concurs with a study in western Kenya where male children had an increased risk for ID compared to females(44) and in Pakistan, being female was associated with reduced odds for IDA(40).
Children with current diarrhoea episodes were 1.7 times more likely to have IDA compared to those without diarrhoea. This is because diarrhoea interferes with iron absorption due to the short transit time of feeds and damage to the microvilli responsible for iron absorption(45). The study findings agree with a study in Indonesia where current diarrhoea was 1.2 times more likely to be associated with IDA compared to those without diarrhoea (46). Additionally, this study concurs with a study in Nepal where one in every 3 children with acute diarrhoea had depleted iron stores and 31.0% of the anaemia observed among the study participants was due to iron deficiency(47). Whereas studies have shown that diarrhoea is associated with IDA due to reduced absorption, it is also possible that diarrhoea can occur as a result of IDA. This is because iron deficiency is associated with reduced immunity leading to recurrent infections including those of the gastrointestinal tract (48).
Children with poor acceptable meal frequency were 1.8 times more likely to develop IDA compared to their counterparts that had an acceptable meal frequency. This is because poor meal frequency limits the iron provision from complementary feeds to cater for the accelerated iron demand for the fast-growing infant. Additionally, reduced meal frequency renders the child more dependent on only breastmilk which isn't sufficient to supply the required nutrients including iron above 6 months of age(49, 50). The study findings concur with a study in northern Uganda where lack of complementary feeding and insufficient complementary feeding increased the risk of IDA by four times and two times respectively(26). Additionally, the study agrees with a study in Kenya where low diet intake was observed as a major cause of anaemia in children aged 6 months to 14 years(51).
Children who never ate vegetables in 7 days before the study were 2.5 times more likely to have IDA while Consuming Fruits once in the 7 days before the study increased the likelihood of developing IDA by more than 90% compared to those that consumed vegetables and fruits more than 5 times in the 7 days before the study. This is because vegetables and fruits contain iron and vitamin C which play a crucial role in enhancing iron absorption from the non-haem iron from the cereals-based diets which predominates the staple foods in the region (52, 53). Plant sources are highly rich in iron but iron is not readily bioavailable as only 5–15% is available for body absorption(52). One of the reasons for the low uptake of vegetables among children is the misconception that it is not acceptable to feed children vegetables and not palatable to the children in face of more palatable foods (54). Another negative impact of vegetables is the high content of phytate and phenolic compounds which inhibit iron absorption in the gut. Thus considering a particular food item may be misleading but rather a complete meal philosophy is more inclusive, especially balancing between enhancement (ascorbic acid, heme iron, and fermented foods) and inhibition(52). This study's findings agree with a study in South Africa where consumption of "vegetables and fruits other than vitamin A-rich'' was associated with lower odds of being anaemic at both 24-hour recall and 3-day recall(55). Furthermore, it concurs with a study in Tanzania and Brazil where not consuming vegetables and consumption of fruits/fruits juice < 2 portions/day increased the risk for IDA by two times (56).
Accordingly, WHO recommends special attention to foods that enhance iron absorption/ consumption of fruit and vegetables as a way to mitigate the burden of IDA among children the world over(32).
The study found a strong positive significant correlation between RDW in presence of microcytosis and Mentzer index in the diagnosis of iron deficiency anaemia (spearman correlation coefficient 0.521, P value 0.000). This implies that both tests are very likely to give the same result when used independently. The study findings of a strong correlation between RDW and Mentzer index are supported by a meta-analysis comparing numerous red cell indices in differentiating IDA and beta thalassemia found a sensitivity of 1.0(0.5–1.4) at 95% confidence interval, p-value false positive rate < 0.001-0.5(-0.9 to -0.1) and a P value of < 0.001 using RDW as reference (57). Additionally, a study comparing RDW and Mentzer index found a sensitivity of 94.2% and 99.4% and PPV of 98.8% and 97.7% for the diagnosis of IDA when compared with serum ferritin among primigravids in Pakistan(20). During iron deficiency, smaller RBCs are produced by the bone marrow resulting in a smaller RBC count and low MCV thus a Mentzer index of > 13(58). Therefore, RDW and Mentzer index can be used for early presumptive diagnosis of IDA and thus early initiation of treatment to avert the complications and long-term sequelae associated with IDA.
Limitations
The gold standard of serum ferritin for IDA was not used. However, the researcher diagnosed IDA based on RDW in presence of microcytosis (low MCV and peripheral blood film smear).