Prevalence of Iron Deficiency, Anemia, and Associated Factors in a Blood Donor Population in Brazzaville, Congo

Introduction Blood donation is not without risk to the donor. It results in a substantial loss of iron and decreased hemoglobin. In our country, no predonation assessment is carried out and the selection of blood donors is only clinical. Objectives To determine the prevalence of iron deficiency, anemia, and iron deficiency anemia and to identify the factors associated with anemia and iron status in a blood donor population at the National Center for Blood Transfusion (NCBT). Methodology. A prospective study is carried out that consists of 120 blood donors in three NCBT branches in the capital from June to November 2021. The donors were divided into 3 groups: first time donors (FTDs), occasional donors (ODs) who have already made between 1 and 3 previous donations, and regular donors (RDs) with at least 4 previous donations. Iron deficiency was defined by a serum ferritin value of less than 30 ng/mL in men and 20 ng/mL in women. Anemia was defined by Hb levels below 13 g/dL in men and 12 g/dL in women. Iron deficiency anemia was defined by association of anemia and iron deficiency. The chi-square test was used for the comparison of the proportions. The odds ratio with the 95% confidence interval was calculated to assess the association between two variables. The p value of the probability was considered significant for a value < 0.05. Results Mean serum ferritin and hemoglobin values were lower in RD in both sexes. The prevalence of iron deficiency, anemia, and iron deficiency anemia were 16.66%, 31.66%, and 10.83%, respectively. The factors associated with the three abnormalities were female sex, donor type, including RD, and number of previous donations. Conclusion Iron deficiency, anemia, and iron deficiency anemia are common among blood donors in Brazzaville. Anemia affects almost a third of blood donors and is not always linked to iron deficiency. Safety of donors should be improved by systematic measurement of ferritinemia and hemoglobin levels before allowing donations for appropriate management in the event of abnormalities.


Introduction
Blood transfusion is an essential replacement therapy for many patients during various medical and surgical conditions.Transfusions of erythrocyte concentrates are performed in dozens as part of intensive oncology treatment, chronic anemia, a severe hemorrhagic accident, or an organ transplant.Blood donation is regulated by regulations whose purpose is, on the one hand, to guarantee the safety of blood transfusions made by blood products derived from these donations and, on the other hand, to preserve the health of donors.To reduce the infectious risk of transfusion, WHO recommends the use of voluntary but regular blood donors.Tus, they constitute a population at risk of iron defciency and of anemia [1,2].Blood donation results in a substantial loss of iron and a decrease of approximately 1 g/dL in hemoglobin (Hb) with each collection procedure, during which up to 425 to 475 ml of total blood is collected [3,4].
To prevent these risks and avoid inappropriate donations, a number of strategies are being implemented by some teams, including limiting the annual number of blood donations and predonation screening for iron defciency and anemia leading to deferral of blood donation below a certain threshold of eligibility for blood donation [2,5,6].In Africa, its practice is not systematic, and several studies have shown that iron defciency and anemia in general are frequent and can afect, respectively, up to 63% and 36.5% of blood donors [7][8][9][10][11].Furthermore, iron defciency was the main but not exclusive cause of anemia.In the Republic of Congo, the practice of blood transfusion is important, and every year, more than 40,000 blood donations are made.Tese are preceded by a medical examination, including an interview aimed at screening for conditions that are contraindicative of donation and assessment of general health [12].However, no hemoglobin and ferritinemia estimation is performed.Tus, in order to strengthen the safety of blood donors, we carried out this study, the frst of its kind, whose objective was to determine the frequency of iron defciency, anemia, and iron defciency anemia in a population of blood donors and identify the associated factors.

Methodology
It was an analytical cross-sectional study that took place over a six-month period from June 1 to November 30, 2021.It was multicentric and was carried out in three of the four stations responsible for blood collection in Brazzaville, capital of the Republic of Congo: those of the teaching hospital, the specialized hospital Mère-Enfants Blanche Gomes, and the reference hospital of Makélékélé.Blood donors were recruited consecutively during the predonation interview.Tose who met the eligibility criteria for blood donation, being between the ages of 18 and 60 years old, weighing 55 kg or more, and qualifed by medical selection were selected for the study, having given their consent to participate.Tose whose sampling process has not been completed due to difculty in drawing blood and those whose determination of ferritinemia could not be carried out for hemolysed serum were excluded.Te variables analyzed were sociodemographic (age, sex, type of donor, and number of previous donations) and biological (Hb level and ferritinemia).Tree types of blood donors have been identifed, all unpaid: (i) First-time donors (FTD).Donors who never had donated blood in the past (ii) Occasional donors (OD).Donors who have previously made between 1 and 3 donations in their lifetime regardless of the time between donations and/or since the last donation (iii) Regular donors (RD).Donors who have previously made at least 4 donations in their lifetime regardless of the time between donations and/or since the last donation Before the total blood donation, 10 ml of blood was collected from a crease elbow vein: 5 ml on an EDTA tube for hemoglobin determination and 5 ml on a dry tube for ferritinemia.Te analyses were carried out at the Faculty's Laboratory of Training, Research, and Analysis of Medical Biology of Health Sciences at Marien Ngouabi University in Brazzaville.Te blood count was carried out on the HORIBA MEDICAL Yumizen H550 machine.Te determination of ferritinemia was carried out using the Bio Mérieux mini vidas semiautomaton using the ELFA technique.Iron defciency was defned by a ferritinemia value of less than 30 ng/mL in men and 20 ng/mL in women.Anemia was defned by a Hb level of less than 13 g/dL in men and 12 g/dL in women.Iron defciency anemia was defned by association of anemia and iron defciency.
Te infuence of the dependent variables was highlighted, thanks to the application of Fisher's exact test on our data.Te statistical diference observed between the qualitative variables was assessed by the Pearson Khi2 test.Te p value of the probability was considered signifcant for a value < 0.05.

Results
Table 1 shows the distribution of a population of blood donors by sociodemographic characteristics in Brazzaville, Congo.
Te sex ratio was 4/1.Te average age was 34 years ± 10 years with extremes of 18 and 60 years.
Among the 26 women, there were 24 (92.31%)FTD, 02 (07.69%)RD, and no OD.Among the 94 men, there were 59 (62.77%)FTD, 27 (28.72%)RD, and 8 (8.51%) OD.Te median value of ferritinemia in blood donors was 74.03 ± 16.74 ng/mL.It was 88.46 ± 14.76 ng/mL ± in men and 53.08 ± 22.94 ng/mL ± in women.Te median Hb value was 13.80 ± 2.81 g/dL.It was 14.25 ± 1.94 g/dL in men and 11.70 ± 4.58 g/dL in women.Table 2 presents the mean values of ferritinemia and Hb levels in a blood donor population by the blood donor type and sex in Brazzaville.
Table 3 shows the prevalence of iron defciency, anemia, and iron defciency anemia in a blood donor population in Brazzaville, Congo.
Among the 20 blood donors with iron defciency, 13 or 65% were in the anemia stage and the remaining 7 were in the preanemic stage.
Concerning the 38 blood donors who had anemia, it was linked to iron defciency in 13 cases (34.21% of anemia).Anemia was therefore undetermined in 65.79%.
Table 4 shows the correlation between the presence of iron defciency, anemia, and iron defciency anemia in blood donors and the sex, type of donor, and number of previous blood donations.

Discussion
Te male predominance of blood donors (78.33% of cases) observed in our study is common in sub-Saharan Africa, as shown by several studies: 79.9%, 80.6%, and 89.3%, respectively, in Nigeria [13], DRC [8], and Ghana [10], up to 95.1% in our country [12].Tese high proportions could be explained among other things by the contraindications of blood donation that are numerous in women, especially breastfeeding, menstruation, or pregnancy less than 6 months old.However, cultural causes should be sought, since studies carried out in Western countries report almost equal proportions of male and female blood donors [6,14] more globally; WHO reports that 33% of blood donations come from women [1].
Te majority of blood donors in our country remain replacement donors as reported in a previous 10-year study [12].With a shortage of blood products in the country, families often have no choice but to donate replacement blood and hope to beneft from a blood product in the future.According to WHO data, of the 118.5 million blood donations collected annually worldwide, 40% are collected in high-income countries, where 16% of the world's population lives.Tere are 31.5 blood donations per 1,000 population in high-income countries, compared to 5.0 in low-income countries, which still collect more than 50% of their blood supply through ofsetting or paid donations [1].
Te design limitation in our study is the fact that the subclinical infammation using at least CRP was not screened, knowing that ferritin is an acute phase protein and will be artifcially increased by infammation.Tis is apparent in the results since ferritin levels were as high as 1200 ng/mL in some participants which is indicative of either infammation, and/or iron overload.It also implies that the prevalence estimated for iron defciency or iron defciency anemia might not refect the true picture in the study population since some iron-defcient individuals might have been qualifed as not being iron-defcient.
Iron defciency in blood donors is a global problem [3,8,[14][15][16][17][18][19].Te frequency found in our series, of 16.66%, seems low compared to those reported in Africa: 17.5% in a large population of nearly 4,500 blood donors in South Africa [15], 20.6% in Nigeria [16], just over a quarter (27.4%) in Ghana [10], 35.2% in Algeria [9], or 63% in the DRC [8] to name but a few.But, as suggested above, the hemoglobin estimation might have been adversely afected by the absence of subclinical infammation screening; therefore, anemia prevalence might have been underestimated.In the last two studies, the high proportions of iron defciency could be explained by the fact that regular blood donors were the most numerous and the prevalence of iron defciency was higher among these regular donors than among other types of donors.In lesser developed countries where iron defciency is already a public health problem, the prevention of anemia in general and iron defciency anemia, in particular, must be an essential issue for the safety of the blood donor but also for quantitative and qualitative self-sufciency in blood products.Indeed, iron defciency can be the cause of anemia with multiple clinical implications in relation to the decrease in oxygen transport in the body.
Tis prevention is based, on the one hand, on the postponement of donors whose Hb level is below a regulatory threshold and, on the other hand, on the prevention of iron defciency.Several measures can be used: the increase in the minimum interval between two total blood donations and/or the reduction in the maximum annual frequency of donations; the assay of serum ferritin measuring iron reserves and fnally donor iron supplementation [2,17,18,[20][21][22].In France, after modeling diferent scenarios measuring the loss of donations, it was decided to opt for a ferritinemia strategy directed at groups at risk of iron defciency with postponement of 6 months if ferritinemia  <15 ng/ml and spacing of donations if between 15 and 25 ng/ ml [17].Regular monitoring of ferritinemia allows individualization of the blood donation calendar in Canada [23].In the face of the ongoing challenge of the blood supply facing many African countries [1,24], it is not easy to address the problem of iron defciency and anemia in front-line blood donors and reach a consensus.Some experts oppose systematic substitution treatment after donation, fearing to mask an iron defciency not related to the donation [17].Determining suitability for donation through isolated dosing of Hb prior to donation would at least not aggravate preexisting anemia.
In our study, nearly, a third of donors had anemia (31.66%) of which 34.21% were iron-deprived, confrming some observations that iron defciency accounts for a signifcant share of anemia in blood donors, especially the most regular [25][26][27].More than 65% of the anemia is not being attributed to iron defciency.Tis high proportion of anemia illustrates the need for a predonated biological assessment to diagnose, explore, and adequately manage potential future donors.Troughout the world, the most common cause of anemia is martial defciency, due to prolonged defciency resulting from inadequate dietary iron intake, increased requirements during growth or pregnancy, and increased losses due to menstruation or helminthiasis.In Africa, and more particularly in tropical zones, apart from genetic causes (especially sickle-cell anemia), other important causes include infections and nutritional defciencies in folic acid and vitamin B12.In areas of high prevalency, anemia is an important complication of malaria [28,29].Blood donor management should be comprehensive, addressing both nutritional and non-nutritional causes of anemia as appropriate.
Factors associated with iron defciency on the one hand, and with anemia and iron defciency anemia on the other hand, were, respectively, the number of donations (especially after the third) and the female sex.Tese are factors traditionally reported in the literature [6,7,9,17,25,30].In the Nzengu-Lukusa study in the Democratic Republic of Congo, iron defciency was associated with the male sex: 70.42% in men compared to 33.33% in women.Tis may be due to the fact that family donors were not included in the study and regular donors are primarily male [8]. 4 Anemia

Conclusion
Iron defciency, anemia, and iron defciency anemia are common among blood donors in Brazzaville, especially among women and RD.In addition, the risk increases with the number of donations.Te safety of donors should be improved by simple measures such as systematic measurement of ferritinemia and measurement of Hb levels prior to allowing donations.Tis predonation screening of iron defciency and anemia will make it possible to carry out an etiological survey and then a curative and preventive management adapted to the diferent causes.

Table 1 :
Distribution of a population of blood donors by sociodemographic characteristics in Brazzaville, Congo.

Table 2 :
Mean values of ferritinemia and Hb levels in a blood donor population by the blood donor type and sex in Brazzaville, Congo.

Table 3 :
Prevalence of iron defciency, anemia, and iron defciency anemia in a blood donor population in Brazzaville, Congo.

Table 4 :
Correlation between the presence of iron defciency, anemia, and iron defciency anemia in blood donors and the sex, type of donor, and number of previous blood donations.