Geostatistical analysis for spatial distribution of anemia (Hb level) among women of reproductive age and determinant factors

Abstract The study was designed to assess the geostatistical spatial distribution of anemia and determinant factors among the women of reproductive age group (RAG) in Gilgit district, Pakistan. The Hb levels for 15–25 RAG, 26–35 RAG, and 36–45 group showed 10.22 g/dL, 10.41 g/dL, and 9.90 g/dL levels, respectively, while the Hb level showed a nugget/sill ratio of 0.21 inferring strong for the 15–25 group, weak for the 26–36, and moderate for 36–45 spatial dependence. Furthermore, 15–25 RAG showed 8% severe and 33.34% sufficient cases and 26–35 showed 12% severe and 29.33% sufficient results in their Hb level, whereas 36–45 had 9.34% severe and 29.33% sufficient.

National Nutritional Survey (MNH, 2018), about 41.7% of women of reproductive age are anemic with a slightly higher proportion in rural (44.3%) than in urban settings (40.2%), while WHO Global reported Pakistan's proportion of the population with anemia up to 50.9% a severe condition. Furthermore, WHO recommended a target of a 50% reduction of anemia among women of reproductive age by 2025(WHO, 2014. Therefore, the study was designed to achieve the WHO global nutrition target 2025 and to explore major factors of anemia, useful in timely interventions in its prevention across the region among women of RAGs.

| MATERIAL S AND ME THODS
The current study was conducted in Gilgit district and divided into three strata (I, II, and III). A total of 675 women with three RAGs (15-25, 26-35, and 36-45) were randomly selected from three strata of the district. Within each stratum 225 and each RAG of 75 women were selected ( Figure 1).

| Anemia (Hb level) analysis
At the time of enrollment, 10 μL of blood was collected as described by standard procedures. The hemoglobin concentration was determined by a handheld instrument, called a hemoglobinometer.

| Statistical analysis
Statista 8.1 software was used to assess, descriptive statistics, and analysis of variance.

| Geostatistical analysis and mapping
Geostatistical analysis was employed to describe the spatial distribution of Hb level in women of RAG. ArcGIS 10.4 and ArcGIS Geostatistical Analyst were exploited for mapping of Hb level. The kriging technique was used to interpolate the values of unsampled locations as described by Caers (2003). The following formula was used for kriging; Where Z (s i ) is the measured value at the ith location, λ i is an unknown weight for the measured value at the ith location, s 0 is the prediction location, and N is the number of measured values.
Semivariogram can be fitted with a spherical model, presented by (Olea, 2012); Spatial dependence (SDP %) was calculated as described by Biondi et al. (1994) and is given by the following expression; For the spherical semivariogram: SDP Spherical (%); ≤2.5% strong spatial dependence; 25% <SPD (%) ≤75% moderate spatial dependence, and ≥75% weak spatial dependence. The spatial analyst function of Arc GIS software was used to prepare maps as described by Hussain et al. (2019).

| Determinant factor of anemia
This study was based on primary data collected from women of different RAG in Gilgit district during the year August 2020 to March 2021. A sample survey was undertaken and personal interviews were conducted to collect information about determinant factors of anemia. HemoGet Hemoglobin testing system (Certeza) was used for the anemia estimations in the study (Figures 2 and 3).

| Sample size
The survey was based on 120 women of RAG randomly selected from the study area. Forty women of each reproductive age were selected. The analysis was carried out concerning percentage analysis by using the following formula: Frequency % = No of responses from each question/Total number of respondents ×100.

| Descriptive statistical analysis
positive correlation with the 36-45 group and the age group 26-35 presented a negative correlation with the 36-45 group ( Table 3).

| Geostatistical analysis
Spatial variability of Hb level in women of RAG was measured by semivariogram method followed by analysis and fit into the spherical model. The nugget-sill ratio was used to assess the spatial dependence of Hb level in women of RAG. The age group 15-25 showed strong spatial dependency, while 26-35 presented weak and 36-45 had moderate spatial dependence (Table 4) correlation, respectively.
Nonetheless, the parameters of the spherical model were fruitful for inverse distance weight (IDW) to produce the spatial distribution maps of the Hb level of women of RAG in the study area. Maps indicate that all three strata of different RAG depicted mild-tomoderate Hb level outcomes with very low frequency of Hb level in Gilgit district ( Figures 5 and 6).

| Determinant factors for anemia at individual level
Anemia is among common health problems throughout the world, especially in developing countries including Pakistan (Habib et al., 2020 was calculated as 50%, the married population was 28%, and the menopause population was 22%. Gilgit district results showed that women of reproductive age between 15 and 26 are suffering from anemia due to area (rural), unhealthy diet, lack of awareness, and menstrual blood loss which are considered the determinant factors.
Furthermore, lactating mothers are more likely to have anemia than nonlactating mothers (Siddiqui et al., 2017). Similarly, according to the current status of the reproductive age women, 32% were pregnant, 11% were lactating, 17% were both, 22% were unmarried, and 18% were none of them, unfortunately, anemic cases were observed in all the age groups.
Moreover, some studies showed that older age is another important and significant determinant of anemia (Kamruzzaman et al., 2015).
Likewise, women having more children were at risk of anemia as demonstrated in some research studies (Page et al., 2015). In Gilgit district, women between the age of 36 and 45 were only 2.66% with severe anemic conditions due to healthy diet, awareness, and targeted interventions. The results are similar to the results established by Kamruzzaman et al. (2015), reporting about 9.34% of anemic cases in 36-45 reproductive-age women. The women aged 40-49 had a lower anemic as compared to women aged between 15 and 19 years. This finding is in line with early studies evaluated by Alaofè et al. (2017)  18% of respondents hired servants for the preparation of their meals, 61% prepare themselves, and 21% were others. According to a diet-related survey, 26% of women believed that fish and meat make blood, while 13% think fruits and vegetables make blood, 20% of respondents think grains and legumes make blood, 24% told that milk and butter make blood, and 7% told all food can make blood.
Likewise, iron absorption can be significantly reduced by tea consumption (Alzaheb & Al-Amer, 2017). In 2015, Dutch dietary guidelines recommended that drinking three cups of tea daily can associate with a lower risk of stroke and diabetes. However, drinking too much green tea may lead to iron deficiency (Lazrak et al., 2021).
The negative relation of tea (too much) with anemia has been also reported due to a reduction in iron absorption (Bansal et al., 2020;Feleke & Feleke, 2018), and others. Our questionnaires about tea consumption showed that 34% of respondents take tea per day, 21% consume it two times per day, 30% take it three times, and 14% take it four times per day.
Likewise, the association of certain diseases such as malaria, hookworm infestation, and chronic illness with anemia is also reported in different studies.

Malaria infection in humans by
Plasmodium species is associated with a reduction in Hb levels causing anemia (Rogerson, 2017). Our findings showed that 12% of respondents suffered from malaria, 31% of respondents suffered from diarrhea, 59% of respondents had intestinal worms problems, and 11% of respondents had different chronic ailments. The results were similar to the findings reported by Kibret et al. (2019) and Alaofè et al. (2017). Meanwhile, intestinal worm result was higher than those reported by Bolka and Gebremedhin (2019)) because groundwater with fecal bacteria has the direct approach to the epidemic of waterborne diseases such as diarrhea, intestinal worms, and typhoid.
Our current study supported that the people living in rural areas, poor wealth index, malaria, and worm infestation had positively associated with anemia. In addition, early studies also established that people with a history of infection cause anemia through loss of nutrients, decreasing appetite, decreasing efficiency of absorption, and use of nutrients. Higher prevalence of anemia among women with parasitic infestations due to the same line of reasoning forwarded for infection (Nadiyah et al., 2021).

ACK N OWLED G M ENT
None.

FU N D I N G I N FO R M ATI O N
None.

CO N FLI C T O F I NTE R E S T S TATE M E NT
All the authors declare that they have no conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The dataset supporting the conclusions of this article is included within the article.