Introduction

The Longitudinal Ageing Study in India (LASI) is a comprehensive research project designed to explore the health, social, and economic dimensions of India's aging population. A collaborative effort led by prominent institutions, including the Harvard T.H. Chan School of Public Health, aims to provide vital data for policy-making and healthy aging initiatives. Tracking over 73,000 individuals aged 45 and older across India, LASI is set to offer insights into aging trends and challenges, aiding in the creation of informed policies and support systems for the elderly [1-3].

Classically Anaemia is defined as reduced oxygen carrying capacity of the blood either due to reduced haemoglobin or due to reduced normal red cell mass [4]. Anemia, affecting approximately one-third of the global population, is characterized by lower-than-normal hemoglobin (Hb) concentration and/or red blood corpuscles (RBC) numbers, leading to an insufficient supply to meet physiological requirements [5]. Iron deficiency anemia (IDA) remains a significant contributor to disability-adjusted life years in the global population, with a notable impact on women's health [6]. In 2020, global maternal mortality stood at 1520 deaths per million live births, potentially underestimated. The World Health Organization (WHO) approximates that each year, between 16,800 and 28,000 deaths occur in women of reproductive age as a result of anemia. IDA complicates 30% to 60% of pregnancies worldwide, with about 75% of individuals affected by the third trimester due to increased iron deficiency. Disparities in IDA prevalence exists, particularly among women of colour and those of low socioeconomic status. Despite its widespread impact, IDA remains underdiagnosed, under researched, and undertreated [7]. Diarrhea is characterized by loose stools and an increase in stool frequency, weight, or volume. It poses a significant health concern, contributing to 2.5 million deaths globally each year [8]. Aeromonas species are increasingly identified as a cause of acute gastroenteritis, but they are less frequently encountered in hospitals compared to other bacteria such as Clostridioides difficile, Salmonella spp., and Escherichia coli [9]. Annually,  approximately 500,000 children under the age of five succumb to acute infectious gastroenteritis worldwide [10]. Zoonoses are illnesses that can be transmitted between animals and humans or from humans to animals. It is estimated that more than 60% of newly emerging infectious diseases in humans have animal origins. The global public health systems face significant challenges due to the impact of zoonotic diseases, leading to over 2 million human fatalities and 2.4 billion cases of illness worldwide each year [11]. In 2019, one-quarter of global deaths were due to infectious diseases, especially in low-income countries, the majority of deaths are caused by infectious diseases [12].

The rising trends of anaemia in India, especially among elderly, is concerning. The causes can vary from acute infections, nutritional causes and chronic diseases [13]. At a base level, surveys have been conducted to estimate the prevalence, a 20% prevalence of anaemia in urban elderly, with more than half of them related to nutritional causes has estimated [14]. In high-altitude regions like Uttarakhand more than 90% of the elderly were anaemic [15]. Pathania et al [16] estimated around 70% in old age homes were anaemic. Concurrently, the burden of gastroenteritis predominantly from waterborne diseases is very high in India. This is attributed to unsafe drinking water, non-availability in some cases, sanitation issues, and poor personal hygiene from the individuals themselves [17].

Anaemia is a major cause of morbidity in elderly individuals, presenting as weariness, sleep difficulties, restless legs syndrome, concentration deficiencies, and female infertility, all of which greatly reduce their quality of life. Blood loss, recurrent infections, nutritional deficiencies caused by insufficient diets, and malabsorption owing to poor absorption are all factors that contribute to anaemia in the elderly [18]. The majority of the strategies and interventions focus on children, adolescents, and pregnant women, and the elderly age group has not garnered enough attention [13]. In contrast, gastroenteritis causes diarrhoea and vomiting, and it is a significant source of morbidity in older persons [19,20]. Anaemia and gastroenteritis both worsen symptoms such as weariness, weakness, cognitive impairment, and dehydration, which have a significant influence on older individuals' health and well-being [21,22]. Diagnosing these illnesses in old age is difficult due to issues such as polypharmacy, medication interactions, medical tolerance, and additional concurrent medical conditions, which frequently result in delayed diagnosis and treatment, affecting care quality. The simultaneous impact of gastroenteritis and anaemia greatly increases healthcare expenditures, including hospitalisations, regular patient visits, and other expenses. The objective of

this study was to utilize LASI data to comprehensively understand the epidemiology, identify risk factors, and develop effective prevention and treatment strategies for anemia and gastroenteritis among the elderly population in India.

Methods

Study design, population and data

We performed a secondary analysis utilizing data gathered from the initial wave of LASI carried out in 2017-2018. The LASI focused on health, economic and social determinants of the ageing Indian population through a nationwide survey. The survey comprised 72,250 adults above 45 years of age and their spouses. Respondents were surveyed in all Indian states and union territories except Sikkim, employing a multistage, stratified area probability cluster sampling methodology. Information on the study design, instruments, data collection and results are summarised and published as the LASI India report and is accessible from a public domain [23]. Our study specifically focussed on the factors associated with gastroenteritis as reported in the LASI data and a probable association of anemia (Figure 1). Number of participants with reported gastroenteritis was 8,275(12.46%).

Figure 1: Association of anemia & gastroenteritis with cross-functional factors

Primary outcome

The primary outcome for our analysis was reported gastroenteritis/ diarrhoea. The primary outcome was assessed from the survey question “In the past 2 years, have you had gastroenteritis/ diarrhoea. The data was dichotomized as gastroenteritis/ diarrhoea "yes" or "no" in our analysis.

Statistical Analysis

The individuals' baseline sociodemographic variables were described using descriptive statistics. All categorical data was represented as frequency and percentages. To estimate the association of anaemia with gastroenteritis, we performed univariate then multivariate logistic regression. Statistical significance is interpreted as a p-valueof 0.05 or less. We used STATA 16 (StataCorp. 2019. Stata Statistical Software: Release 16. College Station, TX: StataCorp LLC) for statistical analysis and visualisations.

Results

Description of study population

and 31,915 individuals recognized as elderly population (60 years of age and older). A total of 66,397 participants were selected for this study.

Prevalence of anemia

In the study conducted across India, anemia was observed with a prevalence rate of 3.89%, affecting a total of 2,586 individuals within the study population. The distribution of anemia prevalence across different states is detailed in Figure 2. The Table 1 represents a thorough evaluation of the socio-demographic characteristics of the patients.

Figure 2: Statewise prevalence of anaemia

Table 1: Socio-demographic characteristics

Of the reported anemia cases, 25.9% (n=672) were from urban areas, while a significant majority of 74.0% (n=1914) were identified in rural locales. Demographically, women were disproportionately affected by anemia, constituting 69.1% (n=1786) of the cases. The age distribution reveals that 51.7% (n=1336) of anemic individuals were between 45 to 59 years old. Education levels among the anemic population showed that 56.2% (n=1453) had not received any formal education. Of those who had some level of schooling, 30.0% (n=340) had completed elementary education, reaching up to standards 5 to 7. Marital status and employment also emerged as notable factors; 72.9% (n=1186) of the anemia cases were among married individuals, and 57.1% (n=989) were among those who were employed. The predominant occupation among the anemic was in the sectors of farming, fishery, and forestry (either owned or family-run), accounting for 37.0% (n=103) of the cases. Self-report of health status revealed that 39.0% (n=994) of the anemic individuals considered their health to be fair. Among those diagnosed with anemia, 39.17% (n=1013) reported experiencing gastroenteritis or diarrhea. Notably, a significant portion of the anemic population, 83.44% (n=2157), had sought treatment for anemia, indicating a high level of healthcare engagement among the affected individuals.

Risk factors associated with gastroenteritis/diarrhea

The Logistic Regression Analysis was conducted on 66,397 participants to investigate the correlation with gastroenteritis. This analysis aimed to discern the relationships between various demographic and socioeconomic variables and the likelihood of gastroenteritis among

the study population. The analysis reveals significant associations across various demographic and socioeconomic variables (Table 2).

Table 2: Logistic Regression Analysis

Age showed a progressively increasing association with gastroenteritis as participants aged, with those 80 years and above having the highest adjusted odds ratio (aOR) of 1.4 (95% CI: 1.3-1.5), although this became statistically non-significant when adjusted for other factors. Gender indicated a marginal association in the crude analysis, with females having an odds ratio (OR) of 1.1 (95% CI: 1.0-1.1) in contrast to men. However, this association disappeared in the adjusted analysis. Self-rated health status emerged as a strong predictor of gastroenteritis, with those rating their health as poor having an OR of 2.2 (95% CI: 1.9-2.5) in the crude analysis. Nevertheless, the significance of this association diminished upon adjustment. Residence type showed a strong crude association, while those living in rural regions had a substantially higher OR of 1.8 (95% CI: 1.7-1.9) than those living in urban areas, but this association was not significant after adjustment. Educational level displayed a gradient effect in the crude analysis, with decreasing odds of gastroenteritis as education level increased. However, adjustments for other variables largely nullified these associations. Marital status highlighted that being widowed, divorced, or separated slightly increased the odds of gastroenteritis in the crude analysis, but these associations were not significant after adjustments. Employment status and main job categories also showed varying degrees of association with gastroenteritis in the crude analysis, but these associations were generally weakened after adjustment. The most notable result showed that the incidence of gastroenteritis and anaemia had a strong connection. The likelihood of developing gastroenteritis was five times higher in those with anaemia (OR = 5.0, 95% CI: 4.61-5.44), which remained significant even after adjustments (aOR = 5.0, 95% CI: 3.44-7.42).

These findings underscore the intricate relationships between socio-demographic factors, health status, and the risk of gastroenteritis, with a particularly strong link between anemia and the likelihood of experiencing gastroenteritis.

Discussion

The current study offers valuable gain in understanding the burden of anemia and its link with gastroenteritis among the elderly population in India, utilizing data from the LASI. The findings highlight the substantial prevalence of anemia at 3.89% within the study population, aligning with previous reports indicating a significant burden of anemia among older adults, particularly in low- and middle-income nations [24]. Notably, the study revealed a striking five-fold increase in the likelihood of experiencing gastroenteritis among individuals with anemia, even after accounting for potential confounding factors. This finding corroborates prior research demonstrating a link between anemia and heightened susceptibility to gastrointestinal infections [25,26], as anemia can impair immune function and compromise the body's ability to mount an effective defense against infectious pathogens [27], also malnutrition and iron deficiency have been shown to raise the chance of getting gastroenteritis. The integrity of the mucosa and the absorptive capacities of the stomach epithelium, which has a rapid turnover rate, depend on sufficient nutrition. Defective epithelial development is the outcome of a persistent lack of tissue iron. Additionally, anemia's overall weakening of the immune system would raise the danger of gastroenteritis [28]. The study also shed light on the disproportionate impact of anemia on specific demographic groups. Women were significantly more affected, constituting 69.1% of anemia cases, consistent with the well-documented global gender disparity in anemia prevalence [29,30]. This disparity can be attributed to factors such as menstrual blood loss, increased iron requirements during pregnancy and lactation, and nutritional deficiencies [31].

Furthermore, the study revealed a higher prevalence of anemia in rural areas (74.0% of cases) compared to urban regions, aligning with previous research documenting higher rates of anemia in rural populations, potentially driven by factors like limited access to healthcare, poor nutrition, and lower socioeconomic status [32]. Interestingly, the study also highlighted the association between anemia and certain socioeconomic factors, with a substantial proportion of anemic individuals lacking formal education (56.2%) and being employed, predominantly in the farming, fishery, and forestry sectors. These findings underscore the complex interplay between socioeconomic determinants, occupational factors, and the risk of anemia, warranting further investigation [33].

The high proportion of anemic individuals (83.44%) seeking treatment for their condition is an encouraging finding, suggesting a relatively high level of healthcare engagement among the affected population. However, it also highlights the need for continued efforts to improve access to effective anemia management strategies, particularly in vulnerable populations [34].

While the study provides valuable insights, certain limitations should be acknowledged. The cross-sectional nature of the data precludes the establishment of a causal relationship between anemia and gastroenteritis, and this research relied on participants' self-reported information, which may be influenced by recall bias and potential under- or over-reporting of symptoms and conditions. Future research should consider longitudinal study designs to elucidate the temporal relationship between anemia, gastroenteritis, and other potential risk factors. Additionally, incorporating objective measures of anemia and gastroenteritis, as well as detailed information on dietary patterns, nutritional status, and comorbidities, could provide a more comprehensive understanding of the complex interplay of factors contributing to these conditions.

Future directions

The exploration of socio-demographic factors influencing the prevalence of gastroenteritis has predominantly focused on pediatric populations in developing countries, leaving a gap in understanding the impact on other demographics [35-37]. Our study, utilizing data from LASI Wave 1, presents an additional perspective by examining this issue within the aging population of India, offering comprehensive insights into health, social, and other demographic aspects. Notably, we uncovered a significant association between anemia and gastroenteritis, even after adjusting for confounding factors. This finding underscores the need for further investigation into the underlying mechanisms linking anemia and gastrointestinal infections. Moreover, understanding the etiology of anemia is crucial for gaining a comprehensive understanding of the pathophysiology. Future research should prioritize clinical validation of self-reported diagnoses, conduct multifactorial analyses to comprehensively assess various influences, and employ randomized study designs to strengthen the available evidence. Additionally, investigations into healthcare access, quality, nutritional interventions, and psychosocial factors are imperative for developing holistic approaches to disease prevention and management, thus warranting evaluation in future studies.

Strengths and Limitations

To the best of our knowledge, this study represents the largest investigation providing valuable insights into the prevalence and association of socio-demographic risk factors of age-related gastroenteritis in India, utilizing a nationally representative, comprehensive longitudinal dataset that enhances the study’s validity and reliability. A notable observation has been the increased odds of gastroenteritis observed among anemic individuals provided, given that most studies aiming to explore this association have been performed on pediatric populations [38,39]. However, certain limitations must be considered while interpreting the results. Firstly, the reliance on self-reported data is susceptible to recall bias, potentially influenced by factors such as stigma and the misclassification of health conditions. Systematic underreporting of gastroenteritis has been acknowledged in similar studies. Without clinical confirmation of these disease conditions, there is a risk of misclassification bias. Secondly, the observational nature of the study precludes the establishment of causal relationships, necessitating caution in interpreting the findings. Randomized study designs are required to validate the significant associations found in this study. Additionally, long-term follow-up data were not available since we utilized one-year longitudinally collected data. Lastly, despite the comprehensive collection of socio-demographic variables, factors such as income, sanitation practices, and dietary habits, which can act as potential confounders, could not be accounted for. Additionally, we could not determine whether any access to and use of medications could have impacted the outcomes. Despite these limitations, this study offers valuable insights into the epidemiology of gastroenteritis and its association with anemia in India's elderly population, laying groundwork for future research and informing public health interventions, given the scarcity of population-based studies on gastroenteritis in India.

Conclusion

In conclusion, the study underscores the significant burden of anemia among the aging population in India and its strong association with the occurrence of gastroenteritis. The findings

highlight the need for targeted interventions aimed at addressing anemia and its underlying determinants, particularly in vulnerable populations such as women and rural residents. Additionally, the study emphasizes the importance of integrating strategies for the prevention and management of gastroenteritis, given its heightened risk in individuals with anemia. By implementing evidence-based strategies and addressing the complex interplay of socioeconomic, demographic, and health-related factors, the burden of anemia and gastroenteritis can be mitigated, ultimately improving the the wellbeing of India's ageing population and their quality of life.

Supporting information

None

Ethical Considerations

None

Acknowledgments

None

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Author contribution statement

All authors contributed equally and attest they meet the ICMJE criteria for authorship and gave final approval for submission.

Data availability statement

Data included in article/supp. material/referenced in article.

Additional information

No additional information is available for this paper.

Declaration of competing interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

References