Prevalence and Structure of Clinical Forms of Iron-Deficiency Anaemias in Children in the Microregions of the City of Makhachkala

The dissertation is devoted to the study of the prevalence and structure of clinical forms of iron-deficiency anaemias (IDA) in children residing in various microregions of the city of Makhachkala. The research was carried out under the conditions of the Republic of Dagestan, where, over the past two decades, no systematic epidemiological studies on the frequency of IDA in the child population had been conducted. The work examines the multifactorial genesis of iron-deficiency states, including alimentary, socio-hygienic, ecological, and biological factors, and evaluates the role of anomalous geochemical provinces and air pollution in the formation of iron deficiency.

In the course of the study, the prevalence of IDA was investigated in three microregions of the city (Reduktorny, Kirovsky, and 5th Poselok), taking into account the severity of anaemia and the age and sex of the child; a questionnaire was developed to assess socio-biological and economic conditions; the chemical composition of the diet was analysed; the quality of the ecosystem was assessed according to the level of air pollution by toxicants; and a diagnostic table for the verification of IDA was proposed. The data obtained were compared with the results of studies conducted in other regions of the country and abroad, as well as with official statistical reporting data.

One of the most sensitive indicators of the response of the child's organism to the influence of environmental factors is the haematopoietic system, in particular the erythron, which reflects the state of hypochromia and the pre-anaemic condition — latent iron deficiency, the prevalence of which is 2.5–3 times higher than that of iron-deficiency anaemias (IDA) (M.M. Shcherba et al., 1975; L.V. Basova, 1975; Yu.E. Malakhovsky, G.V. Babash et al., 1980; I.N. Bukhalovsky, V.N. Petrov, 1984).

IDA in children has a multifactorial genesis, with iron deficiency in the diet, disorders of iron metabolism, microelements, vitamins, and protein metabolism (T.I. Bida, 1978; V.P. Bisyarina, L.M. Kazakova, 1979; V.N. Petrov, 1982; L.M. Kazakova, 1986 et al.). In such cases, the somatic and mental development of children is impaired. As a background condition, these disorders contribute to a higher frequency of infectious morbidity, chronicity of pathological conditions, a higher frequency of recurrence of chronic diseases, and a shortening of remission periods. Children with reduced haemoglobin levels constitute a risk group, including for IDA (I.V. Koshel, 1986).

According to a number of researchers, iron-deficiency states (IDS) are observed on average in 43% of young children (de Maeyer C. Adiels, Teqman, 1985). In India, IDA is diagnosed in 70% of children aged 1 to 5 years.

In the former Soviet Union, the epidemiology of IDA in children began to be studied in the late 1960s — early 1970s (A.M. Pleshkov, 1970; N.D. Yashanova, 1970; B.N. Petrov, 1972).

The study of the epidemiology of IDA in children is recognised as a priority direction in the Central Asian and Caucasus regions. The higher prevalence of IDA in these regions is likely determined by both natural and socio-hygienic, ethnic characteristics.

According to data from various authors (D.K. Kudayarov, 1977; R.M. Pakhrамов, Kh.K. Farmakulov, 1990; G.A. Izmukhambetov, 1990), in the Central Asian region the prevalence of IDA in children ranges from 22 to 41%. Information on the prevalence of IDA in children in Dagestan in the literature is fragmentary and dates back 14–18 years (P.S. Guseynova, 1978). The author established that iron deficiency was observed in 70.4% of children in rural areas of the republic. A.Sh. Khasaev (1982) found the lowest percentage of IDA in children residing in the city of Makhachkala — 9.3%; his rural data are consistent with the findings of P.S. Guseynova, since they refer, in practice, to the same period.

According to data from the Ministry of Health of the Republic of Dagestan, the prevalence of anaemia among pregnant women was 31.4% in 1993, 38.2% in 1994, and 45.3% in 1995; according to I.A. Shamov et al. (1994), this figure ranges between 21–90%.

Children born to mothers with anaemia, including IDA, can be considered a risk group for IDA, with all its socio-medical consequences.

The results of studies by a number of domestic and foreign authors (S.I. Ryabov, 1973; G.E. Ryss, 1974; Yu.N. Tokarev, 1978; V.N. Petrov, 1982; T.M. Sokh, T.I. Peters, 1978; D.M. Walford, K. Deacon, 1980 et al.) have elucidated many issues concerning the aetiology, pathogenesis, diagnosis, prevention, and treatment of IDA. It is noted that the priority aetiological factor in children, in 80–90% of cases, is the alimentary deficiency of protein, iron, and other microelements in the diet, and the imbalance of nutrition. This conclusion is also confirmed by the data of K.R. Sedov and R.N. Butakova (1984). Under the conditions of Eastern Siberia and the North, the authors established a dependence of the frequency of IDA on the amount of biologically important microelements in the ecosystem. I.A. Oparin et al. (1966), as well as G.N. Gereev (1968), arrived at a similar conclusion for Dagestan. The authors confirmed the role of anomalous geochemical provinces in the occurrence of IDA, noting the low content of iron, copper, and cobalt in the territory of the Tersko-Sulak lowland of Dagestan. By this phenomenon, the authors attempted to explain the high morbidity of the population from IDA.

Various aspects of the epidemiology, pathogenesis, and early diagnosis of IDA among the child population of the Republic of Dagestan remain insufficiently studied, which is particularly relevant under rapidly changing socio-economic and ecological conditions.

The statistical reporting of the Ministry of Health of the republic accounts for IDA only according to attendance data. Even according to these data, the frequency of IDA in Dagestan, especially among children and pregnant women, has been increasing from year to year.

S.S. Sadikova et al. (1990) diagnosed IDA in every fifth child; V.I. Krivoruchko et al. (1991) in 47% of the examined children, and latent iron deficiency (LID) in 37%.

L.V. Yevets et al. (1992) and A.A. Rezaeva (1996) revealed the influence of a polluted atmospheric environment on the frequency of peripheral blood pathology. In the Moscow region, hypochromic states under polar ecological conditions ranged from 2.17 to 7.6%.

The prevalence of IDA among children residing in cities with an aggravated ecological situation is 1.7 times higher (A.F. Babtseva, 1995).

M.Ya. Berlinson et al. (1995) detected IDA in 15.1% of 887 examined children. Of these, 84.4% were diagnosed with mild anaemia, 11.9% with moderate anaemia, and 3.7% with severe anaemia.

L.M. Kazakova (1997) detected anaemia in 12% of examined children of early age in the 1980s, in 32% in 1995, in 25% of preschool-age children, and in 62% of hospitalised children. In Novokuznetsk, IDA was diagnosed in 24.7% of children aged 2 years, in 39.5% in the second half-year, in 8.2% of children older than 3–6 years, in 6% at 7–11 years, and in 5% at 12–13 years (Yu.E. Malakhovsky et al., 1988). These data indicate that the frequency of IDA decreases with age, with the greatest risk observed in early childhood.

V.N. Vasilyev (1995) diagnosed hypochromic states in 64% of children.

An important factor accompanying IDA, LID, and hypochromia in children is the significantly higher frequency of frequently ill children: 55.5% in IDA and 35.4% in LID. The frequency of anaemia and iron-deficiency states in mothers is a real risk factor for IDA in children. Among the risk factors for IDA in children, ecological factors influencing the formation of iron deficiency, the influence of nutrition, maternal anaemia, early age periods, etc., should be noted. IDA is a pathology of multifactorial genesis with severe consequences for the somatic and mental status. The prevalence of IDA in children, according to data from various authors, varies widely and is high not only across cities but also across microregions of cities and in rural areas. Over the past two decades, no studies on the frequency of IDA in children have been conducted in the Republic of Dagestan, either in cities or in rural areas.

The study of the epidemiology of IDA in children across the microregions of the city of Makhachkala has never been conducted at all.

The literature data on the prevalence of IDA in children testify not only to the socio-medical significance of iron-deficiency states but also to the importance of the influence of the micro- and macro-ecological regional element. Given the high frequency of IDA in children and its multifactorial genesis, the aim of the present study is to identify the characteristics of the prevalence and structure of IDA in the child population of various microregions of the city of Makhachkala and the exogenous and endogenous risk factors for their occurrence.

To achieve this aim, the following tasks were addressed in the work:

1) To study the prevalence of IDA in children of the Reduktorny, Kirovsky, and 5th Poselok microregions of the city of Makhachkala, taking into account the severity of anaemia and the age and sex of the child; to establish the criteria of IDA for diagnostic verification.

2) To develop a questionnaire for studying socio-biological and economic conditions and to rank the most significant risk factors.

3) To evaluate the chemical composition and quantitative characteristics of the diet as a risk factor for IDA in children.

4) To evaluate the quality of the ecosystem as a potential risk factor for iron-deficiency anaemias according to the level of air pollution by toxicants.

5) To assess the informativeness and practical significance of the diagnostic table for IDA in the examined children.

SCIENTIFIC NOVELTY

The study revealed a high (43%) frequency of IDA, which significantly exceeds the data of the statistical reporting of the city of Makhachkala.

It has been established that the prevalence of IDA in children of the city of Makhachkala varies considerably not only across microregions (from 36.5 to 61.7%) but also within the territory of the same microregion depending on the age of the children. The highest frequency of IDA was noted in children under 3 years of age, while severe forms of the disease were more often observed in children aged 3–7 years.

For the first time in the Republic of Dagestan, an assessment of the actual nutrition of children with IDA and a control group has been carried out, and the pathogenetic significance of the deficiency of iron, protein, and certain vitamins in the diet of children with IDA has been established.

It has been revealed that, alongside alimentary factors, social and biological factors also exert a significant influence on the prevalence of IDA.

A scheme of the formation of IDS at the individual and population levels has been studied, as well as a hypothesis concerning the impairment of iron transport into the erythron.

A diagnostic table and ranked risk factors have been developed, making it possible to define the ways of implementing anti-epidemic measures at the regional level.

PRACTICAL SIGNIFICANCE.

On the basis of the conducted studies, a set of preventive measures has been proposed with the aim of stabilising and subsequently reducing the frequency of IDA across microregions. The results of the study allow for the assessment of the characteristics of IDA in children across the microregions of the city of Makhachkala, which will contribute to increasing the effectiveness of monitoring IDS among the child population of the microregions of a city with a population of half a million.

Risk factors for IDA have been identified and ranked; these can be used in forming not only risk groups but also in organising clinical follow-up of these children. The obtained data have made it possible to introduce adjustments when compiling dietary regimens for children at risk. When implementing preventive measures, the quality of the ecosystem in the microregions of the city of Makhachkala will be taken into account.

The results obtained and the practical recommendations arising from them have been implemented in the territorial therapeutic and preventive institutions of the microregions of the city of Makhachkala and are recommended for use in the practical public health system of the Republic of Dagestan and other regions of the country.

PUBLICATIONS

Five works have been published on the materials of the research. The research results were discussed at the Republican Conference on Nature Conservation of Dagestan, at the inter-departmental scientific and practical conference of the paediatric departments of the Dagestan State Medical Academy, and at a meeting of the Republican Society of Paediatricians. The research results have been put into practice.

VOLUME AND STRUCTURE OF THE DISSERTATION.

The materials of the dissertation are presented on 102 pages of typewritten text, with appendices amounting to 63 pages; the work is illustrated with 21 tables, 4 graphs, 5 combined tables, 1 cartogram, and 2 schemes. The work uses 273 literature sources, of which 108 are by foreign authors.