Abstract
The purpose of this study was to examine the differences in standard of living between households with migrants and households without migrants in Kerala, one of the most remittance-receiving states in India. Data from the Kerala Migration Survey (2018) was used for the study. The survey sampled 15,000 households, including both households with migrants and without migrants. Cross tabulation, standard living index, and ordered logistic regression analysis were used to examine the difference in living standards between households with migrants and without migrants. A total of 28.4% of households were with migrant and 71.6% were without migrant in this study. The proportion of households without migrants that fell below the poverty line (42.38%) was higher than the proportion of households with migrants (30.13%). A significant percentage of households with migrants (16.3% and 38.7%) lived in houses categorized as “luxurious” and “very good,” respectively, compared to households without migrants (10.4% and 27.8%, respectively). In addition, households with migrants allocated a larger budget for house construction, with costs exceeding ₹5 lakhs, compared to households without migrants. The proportion of households with migrants that owned consumer durables such as vehicles, home appliances, and electronic gadgets was also higher than their counterparts without migrants. In terms of standard of living, households with migrants had a significantly higher proportion of households with a better living standard than households without migrants. Further, households with migrants had a significantly higher likelihood of having a better standard of living than households without migrants (AOR: 1.729; CI: 1.609–1.858). This study highlights the significant positive impact of international migration on the living standard of households, including better housing quality and higher levels of ownership of consumer durables. These findings suggest that international migration can be a positive force for development, leading to improved standards of living for both households with migrants and non-migrants.
Keywords
Introduction
Humans are known to have migrated extensively throughout the history. The people choose to migrate for various reasons, including seeking better employment opportunities or escaping persecution. In lower-income countries, migration is often adopted as a strategy by low-income households to generate income and reduce their consumption levels (de Haas, 2010; S. I. Rajan et al. 2023). The World Migration Report 2019 (IOM, 2019) estimates 270 million international people are immigrants. In terms of the distribution of migrants among countries, India has 17 million migrants, followed by Mexico and China. Additionally, remittances from overseas to India were $689 billion in 2018. With 18 million people living abroad, major corridors of Indian international migration are north America, Gulf Cooperation Council (GCC) countries, and European countries (Khan & Arokkiaraj, 2021).
Remittances, comprising both monetary and material contributions sent by migrant workers employed outside their original location, have undergone extensive study, revealing consistently positive effects at the household level (Srivastava, 2013). These contributions have facilitated upward mobility concerning income and household wealth (De & Ratha, 2012; M. Mahapatro, 2015). Households that receive remittances experience noteworthy improvements in various dimensions of their lives, including increased food and non-food consumption, enhanced housing conditions, higher education expenditure for children, greater healthcare spending, improved access to communication, heightened social acceptance, and increased participation of women in household decision-making (Hassan & Jebin, 2018). Furthermore, remittances play a pivotal role in poverty reduction (Faridi, 2014) and contribute to increased savings, higher monthly per capita spending, and overall consumption among migrant households (Sharma & Zaman, 2013; Srivastava, 2013). These remittances are strategically directed toward investments in real estate, land, and consumer goods, leading to a comprehensive enhancement in the quality of life for migrant households (Revathy, 2020; Srivastava & Sutradhar, 2016). S. R. Mahapatro (2019) specifically highlighted the direct investment of remittances in essential areas such as food, healthcare, housing, education, and consumer durables and goods for households with migrants. Supporting this finding, Hussain et al. (2021) argued that migrants made substantial investments in improving housing quality and access to amenities compared to non-migrants. Moreover, migration demonstrably improved the living standards of migrant households compared to non-migrant households (Feld, 2022; Kumar et al., 2019).
Remittances and migration exert a profound and far-reaching positive influence that extends beyond mere financial contributions, encompassing enhancements in household living standards. They play a pivotal role in propelling economic growth and development, benefiting the regions from which migrants originate and the regions to which they migrate (Ravallion et al., 2007). In recipient countries, migration contributes to growth by catalyzing investments and innovations, thereby stimulating overall economic progress (Nyeadi & Atiga, 2014). Moreover, the impact of migration transcends financial considerations, bringing forth fresh ideas, knowledge, and entrepreneurial mindsets that significantly contribute to the development process (de Haas, 2010). Specifically, remittances wield a favorable impact on various facets of developing countries, including the labor market, income and assets, expenditure and investment, employment opportunities, wages, health, and poverty (Adams, 2011; Srivastava & Sutradhar, 2016). These literatures synthesize diverse studies, providing a comprehensive understanding of the multifaceted impacts of remittances on migrant households.
The Study Context
Kerala, a state in southern India with a 33 million populations, accounts for a huge number of laborers overseas, primarily in the Gulf countries, which includes countries such as Saudi Arabia, the United Arab Emirates (UAE), Qatar, Kuwait, Oman, and Bahrain. Since the Gulf migration began, the flow of remittances has become the focal point of development in Kerala, primarily in underdeveloped regions like northern part of Kerala and communities such as Muslims (Zachariah & Rajan, 2004). The number of emigrants hailing from Kerala is estimated to be around 2.1 million across various countries worldwide and 90 percent of them are working in Gulf countries (S. I. Rajan & Zachariah, 2019).
Migration and the accompanying remittances in Kerala have had a discernible impact on several aspects, including housing, transportation, town planning, educational and religious institutions, amenities, and infrastructure. Migrants and their household often enjoy more opulent housing facilities compared to non-migrants. Additionally, advancements can be observed in the commercial sector, with the establishment of commercial complexes, jewelry outlets, hotels, and hospitals (Azeez & Begum, 2009). The share of remittances to Net State Domestic Product (NSDP) in Kerala is around 20%. These remittances have a considerable impact on the state’s overall development, both explicitly and implicitly. This influence could be directly reflected in the consumption and savings patterns of migrant and non-migrant households (S. I. Rajan & Zachariah, 2019).
While international migration significantly influences the livelihoods of households in Kerala, there remains a significant gap in understanding the disparities in economic status and living standards between households with migrants and those without migrants and there remains a significant lack of comprehensive exploration and understanding of these differences. This study aims to address this gap by examining the differences in the standard of living between households with migrants and without migrants in Kerala. Leveraging data from the latest Kerala Migration Survey conducted in 2018, this paper endeavors to shed light on the socioeconomic dynamics within migrant and non-migrant households, offering valuable insights into the implications of international migration on household well-being in the state of Kerala.
Methodology
Data
This study is based on the Kerala Migration Survey (KMS) 2018, conducted under the Centre for Development Studies, Trivandrum, Kerala, India. The survey covered a sample of 15,000 households from 500 selected localities of the state, using a stratified multistage random sampling method. The 14 districts of Kerala are divided into 28 strata with one rural and one urban stratum in each district. The households were distributed between the district’s rural stratum and urban stratum proportional to the district’s rural-urban households in the 2011 Census. Subsequently, a village from rural areas and ward from urban area were randomly selected, with thirty households chosen from each selected urban and rural locality. Systematic random sampling methods was used to select samples from each village and ward from the available list of households at the time of survey. Suppose there are 300 households in a fixed locality. Dividing 300 by 30 we get the number 10. This number is used to randomly select every 10th household to identify the 30 households for that particular locality.
For the purpose of the study, a total of 15,000 sample households were categorized into two distinct groups: households with migrants and households without migrants. The former group comprised both currently migrant and return migrant households, while the latter group consisted of households that had not experienced migration outside their country of origin. Based on this classification, the number of households that had at least one international migrant, including return migrant, was 4,265, which constituted 28.4% of the total sample. Similarly, households without migrants accounted for the majority, with a count of 10,735, representing 71.6% of the total sample. The data and other resources are publicly available on the website at https://iimad.org/data-bank/
Measures
To facilitate a comprehensive comparison between migrant and non-migrant households, the study employed several variables related to economic status and household assets. These variables encompassed the following:
Ration Card: A government-utilized card system for food item distribution, serving as a crucial indicator for identifying household categories falling below poverty line (poor) or above the poverty line (rich).
Type of House: Categorized based on structural attributes such as luxurious, very good, good, and kutcha house.
House Ownership: Distinguishing between owned and rented residences.
Construction Cost of House: Assessing the financial investment in housing.
Land Ownership: Determining possession or lack of ownership of land.
Ownership of Consumer Durables: Including vehicles, home appliances, and other household assets.
Additionally, a Standard of Living Index (SLI) was constructed by incorporating variables such as the type of house, the type of cooking fuel used, and ownership of consumer durables. This index served as a comprehensive metric to discern differences between households with migrants and those without. To further enhance the comparison, ordered regression analysis was conducted, with the SLI as the outcome variable and control variables included household type (migrant and non-migrant), household size, type of ration card, religion, and ownership of land and house.
Statistical Approach
The present study employed descriptive and cross-tabulation analyses to assess the prevalence of differences between migrant and non-migrant households. Chi-square tests were conducted to evaluate the significance of associations among variables, and p-values were reported accordingly. Additionally, a Standard of Living Index (SLI) was generated using the Principal Component Analysis (PCA) method, executed with Stata software (version 15.1). The SLI was further classified into tertiles using the “xtile” command in Stata, presenting results in low, middle, and high categories. Furthermore, an ordered logistic regression analysis was conducted to examine the association between living standards and migrant and non-migrant households, adjusting for covariate variables. The results were presented in the form of adjusted odds ratios (AOR) with 95% confidence intervals (CI). Household weights were applied during the analysis to ensure the estimates were representative at the state level.
Results
Household Characteristics
Table 1 illustrates the distribution of households with migrants (28.4%) and those without migrants (71.6%), the average number of members per household in Kerala is four. According to the table, a majority of households without migrants (64%) and households with migrants (62.7%) both exhibit a household size within the range of 3 to 5 individuals. In terms of household religious distribution, the data reveals that among non-migrant families, Hindus (63.0%) as the majority, followed by Christians (21.2%) and Muslims (15.6%). Conversely, migrant families demonstrated a different pattern, with Muslims (44.7%) comprising the majority, followed by Hindus (38.2%) and Christians (17.0%).
Background Characteristics of the Household.
The table also presents a comprehensive depiction of the ration card system and its significance in identifying household categories falling below poverty line (poor) or above the poverty line (poor). Notably, almost 95% of the households, irrespective of their migration status, possessed valid ration cards. However, a larger proportion of households without migrants (42.38%) fell below the poverty line, exceeding the average state-level statistics (38%). In contrast, households with migrants demonstrated a higher percentage (69.87%) belonging to the above-poverty-line (rich) category.
Types of Houses and the Attributes
Table 2 presents an analysis of the types of houses, ownership status, construction costs, housing loans, and land ownership among households without migrants and those with migrants. The findings highlight notable differences between the two groups. Specifically, a significantly higher percentage of households with migrants (16.3% and 38.7%) reside in houses categorized as “luxurious” and “very good” respectively, compared to households without migrants (10.4% and 27.8%, respectively). Conversely, a higher proportion of households without migrants live in houses classified as “poor” (17.8%) and Kutcha-style -low cost traditional housing constructed by mud, thatch, bamboo, or corrugated sheets- (5.2%) homes compared to households with migrant (8.2% and 0.7% respectively). In terms of house ownership, the percentage of households with migrants (94.1%) living in owned houses was notably higher compared to families without migrants (92.3%). Whereas, a higher proportion of families without migrants (5%) live in rented houses compared to households with migrants (4%).
Type of House, Ownership, Cost of House Construction, Loan From the Bank, and Land Ownership.
Note. p-Values are based on two-sample proportion test.
Other: relatives’ homes, wife’s homes, and church-owned homes.
A significantly higher proportion of households without migrants constructed houses with a cost of less than ₹1 lakh (14.7%) and between ₹1 lakh and ₹5 lakhs (30.3%) than households with migrants (6.5%, a difference of −8.2% and 19.5%, a difference of −10.8 respectively). Conversely, households with migrants allocated a larger budget for house construction with costs exceeding ₹5 lakhs. This includes houses priced between ₹5 and ₹20 lakhs (45.1%, difference of 9.8%), ₹20 to ₹50 lakhs (19.7%, difference of 10.9%), and over ₹50 lakhs (2.6%, difference of 1.2%) compared to households without migrants (35.3%, 8.8%, and 1.4% respectively). Additionally, the data reveals that 74.2% of families with migrants owned land, while 69.7% of households without migrants possessed land. These findings highlight the divergent patterns in house construction costs and land ownership between households with migrants and those without migrants.
Household Assets and Consumer Durables
Table 3 provides a comprehensive overview of the consumer durables owned by households with migrants and without migrants, encompassing a wide range of items including vehicles, home appliances, and electronic gadgets. Comparing vehicle ownership between the two groups, it is evident that households with migrants have a significantly higher percentage of vehicle ownership, with a greater proportion owning cars (32%, a difference of 7.9%) and scooters (56.4%, a difference of 6.9%), compared to households without migrants (24.1% and 49.5%, respectively). Additionally, households with migrants exhibit significantly higher ownership and usage of electronic gadgets compared to households without migrants. This includes higher percentages of ownership for mobile phones (94.4% vs. 91.6%), computers (20.3% vs. 16.0%), and Wi-Fi internet connections (18.6% vs. 13.8%).
Household Asset and Consumer Durables.
It is worth mentioning that, with the exception of television (89%, a difference of −2.1%), households with migrants exhibit higher ownership percentages of all other household appliances. This includes refrigerator (84.6%, a difference of 19.8%), washing machine (46.6%, a difference of 14.9%), microwave oven (12.9%, a difference of 5.1%), air conditioner (17%, a difference of 8.4%), and inverter (21%, a difference of 9.7%), compared to households without migrants. The cooking fuel type varies between the two groups. Households without migrants had a significantly higher use of wood as fuel (33%) than those with migrants (25.8%, difference −7.2%), whereas households with migrants show a higher proportion of LP Gas (59.3%, a difference of 4.4%) compared to households without migrants (54.9%).
Standard of Living Index
To understand the difference in living standards of migrant and non-migrant households we have calculated the standard of living index using variables such as type of house, type of cooking fuel, and ownership of consumer durables. The index is classified into low, middle, and high categories in Table 4 and presents the standard of living index of both households without migrants and those with migrants. The households with migrants had a significantly higher proportion of ‘High’ (42.1%) and ‘Middle’ (35.7%) living standards as compared to households without migrants (28.9% and 31.9%, respectively), whereas the low level of living standard was significantly higher among households without migrants (39.2%) than households with migrants (22.2%).
Standard of Living Index.
Table 5 shows the results of the analysis estimating the living standard of households in Kerala. Households with migrants had a significantly higher likelihood of a better standard of living than households without migrants (AOR: 1.729; CI: 1.609–1.858). Households with six or more members were 3.2 times more likely to have a high standard of living than households with one member (AOR: 3.279; CI: 2.720–3.953). Households with ration cards that fell below the poverty line were less likely to have a better standard of living than households without ration cards (AOR: 0.352; CI: 0.301–0.413). However, households with ration cards that belonged to the above-poverty-line category had a significantly higher chance of having a high standard of living than households without ration cards (AOR: 2.087; CI: 1.788–2.437). In terms of religion, migration from Kerala has predominantly concentrated within the Muslim community (43%), surpassing the numbers of migrants from Hindu and Christian communities (Rajan & Zachariah, 2019), despite Muslims being a minority community in the state of Kerala. Christian households had a higher likelihood of a good standard of living than Hindu households (AOR: 1.826; CI: 1.682–1.981). Similarly, Muslim households had a higher standard of living than Hindu households, although this was not significant (AOR: 1.005; CI: 0.884–1.142). Households with ownership of a house had a higher, but insignificant, likelihood of a higher standard of living (AOR: 2.087; CI: 1.788–2.437). Finally, households that did not own land were less likely to have a better standard of living than households that owned land (AOR: 0.873; CI: 0.813–0.938).
Ordered Logistic Regression of Standard of Living Index by Household Type, Household Size, Ration Card, Religion, and Ownership of House and Land.
p < .01. **p < .05. *p < .1.
Discussion
Kerala has witnessed transformative developments propelled by the phenomenon of migration. The study delves into the multifaceted impact of migration and remittances on the development of Kerala by improving economic and living standards of households, with a specific focus on the distinctions between households with migrants and without migrants. Through an in-depth exploration of various indicators such as housing quality, asset ownership, consumer durables, and overall living standards, the research uncovers the transformative influence of migration on the socioeconomic landscape. In this context, the findings are particularly relevant in shedding light on the specific developments observed in Kerala, a region where migration has played a pivotal role in shaping socio-economic developments, particularly for marginalized regions.
It is widely acknowledged that in Kerala, remittances are predominantly allocated toward various consumption items, including food, household durables, education, and healthcare, as well as non-consumption or personal items such as housing and repayment of debts. The study by S. R. Mahapatro (2019) confirms this trend, emphasizing that a significant portion of remittances is directed toward both consumption and non-consumption items rather than investments.
The study reveals significant disparities in economic and living standards between households with migrants and those without migrants. These differences encompass various factors such as poverty indicators, housing quality, asset ownership, and consumer durables. Additionally, the study highlights the positive impact of remittances on the development aspects including economic well-being and living standards of households with migrants.
Housing Quality
The research indicates a marked distinction in housing quality, with migrant households generally owning higher-quality and more luxurious houses. This finding aligns with earlier studies by Zachariah and Rajan (2004) and Hassan and Jebin (2018), emphasizing the trend of better housing quality among families with migrants. Notably, many migrants invest a significant portion of their remittances in housing projects in their home countries, reflecting a primary motivation for migration (Adams, 2011; de Haas, 2010). Owning a good and luxurious house is often a primary motivation for migration, as it may not be feasible to make such an investment by staying in their country of origin. As noted by Mazzucato (2005), Ghanaian migrants living in Amsterdam allocate 16 percent of their remittances toward housing investments. Consequently, economically and socially deprived households have started constructing larger, more luxurious houses that not only provide comfort and reflect modern trends in lifestyle but also serve as symbolic representations of foreign wealth and prestige (Hussain et al., 2021). Building a comfortable house with all amenities is a key aspiration of households with migrants, and the availability of remittances has helped realize this desire (Aziz & Mohyuddin, 2015). The findings highlight the substantial investments made by migrants in improving housing quality and access to amenities.
Consumer Durables and Asset Ownership
Ownership of consumer durables and household assets shows a stronger positive association with households with migrants in the study. Migration and remittances positively impact consumption patterns, leading to increased spending on consumer durables and asset ownership, ultimately enhancing the overall economic well-being of migrant households (Ahmed, 2022; Ajaero et al., 2018; Beegle et al., 2011; Qin, 2010). Mergo (2016) further emphasizes that migration predominantly enhances consumer expenditure over savings and business investments among households with migrants.
Land Ownership and Poverty Alleviation
Households with migrants exhibit a higher percentage of land ownership, allocate more funds toward house construction, and have a larger proportion above the poverty line compared to households without migrants. These findings demonstrate the direct positive impact of migration and remittances on the economic well-being of migrant households. Various studies support these results, illustrating the widespread benefits of remittances, including improved health, education, ownership of land and assets, economic prosperity, and access to essential resources (Andersson, 2012; Gartaula et al., 2012; Hoermann et al., 2010; Kapri & Jha, 2020; Medina & Cardona, 2010; Thapa & Acharya, 2017). Pelletier (2012) highlighted the positive influence of remittances in reducing poverty rates and narrowing income disparities within the state of Kerala. These findings further validate the transformative impact of migration and remittances on the well-being and socioeconomic status of households with migrants.
Improvement in Living Standards
The study concludes that households with migrants enjoy a significantly better standard of living compared to their non-migrant counterparts. This aligns with existing research that consistently shows positive impacts of migration on income and living standards (Feld, 2022; Kumar et al., 2019; Miftah, 2015; Semyonov & Gorodzeisky, 2008; Srivastava & Sutradhar, 2016). The positive influence of migration on socio-economic conditions is evident in Kerala, where migration has led to improvements in the well-being of deprived households and communities, especially among Muslims in Kerala (Zachariah & Rajan, 2004).
Multiple studies (Abduvaliev & Bustillo, 2020; Chiwuzulum Odozi et al., 2010; Kóczán & Loyola, 2021; Pfau & Giang, 2009) consistently highlighted the dynamic role of migration in enhancing the income and social status of disadvantaged households and population. These studies emphasize the importance of remittances in reducing poverty, increasing income levels, and improving overall consumption, which helps protect vulnerable populations from the adverse impacts of economic shocks and crises. Ultimately, migration plays a critical role in reducing inequality and poverty (Bang et al., 2016). However, some studies (Chea, 2023; Hobbs & Jameson, 2012; Olowa & Shittu, 2012) revealed that, although remittances may alleviate poverty at the household level, they may inadvertently widen the gap between migrant and non-migrant families, exacerbating income inequality. It’s because the benefits of migration and remittances were primarily concentrated among specific sections of the population, rather than reaching the poorest individuals. Rapoport and Docquier (2006) highlighted that in communities with a long-standing tradition of migration, remittances initially increased income inequality but eventually led to a decrease in overall inequality. These counter-findings suggest that the relationship between migration, remittances, and income inequality is complex and context-dependent. While remittances may contribute to poverty reduction, there is a risk of increasing inequality between different segments of the population.
In short, the study underscores the importance of recognizing and harnessing the potential of remittances and migration as powerful tools for improving living standards. The direct influence of remittances on the standard of living of households with migrants is reflected in the higher expenditures on housing, and ownership of assets and consumer durables which are key indicators for the high-level standard of living and well-being. Therefore, the positive impact of migration on the standard of living of households with migrants cannot be ignored, and it highlights the importance of migration as a means of improving the economic and living conditions of households in developing countries.
In light of these findings, policymakers should prioritize initiatives that recognize and harness the potential of migration as a catalyst for development. By leveraging migration as a potent tool for socio-economic advancement, policymakers can foster sustainable development, reduce poverty, and enhance living standards for households with migrants and those without migrants alike. This holistic approach acknowledges the transformative potential of migration while addressing the complex challenges associated with income inequality and social disparities.
Conclusions
In conclusion, our study sheds light on the substantial and multifaceted impact of migration and remittances on the economic well-being and living standards of households with migrants. The findings reveal marked disparities between households with migrants and without migrants across various dimensions, including poverty indicators, housing quality, asset ownership, and consumer durables. The constructed Standard of Living Index (SLI) accentuates these distinctions, underscoring the elevated living standards of households with migrants.
A key revelation from our study is the pivotal role played by international remittances in fostering upward income mobility among migrant households, leading to tangible transformations in their living standards. Notably, migrants exhibit a distinct preference for investing a significant portion of remittances in housing, manifesting in the ownership of higher-quality and more luxurious homes. This aspiration for improved living conditions transcends geographical boundaries, with remittances serving as a catalyst for constructing larger, more comfortable residences, symbolic of foreign wealth, and prestige. Furthermore, our study establishes a positive association between migration and the ownership of consumer durables and household assets. This association is driven by the transformative impact of migration and remittances on consumption patterns, enhancing the overall economic well-being of migrant households in comparison to their non-migrant counterparts.
Crucially, our findings indicate that migrant households not only surpass non-migrant households in land ownership but also allocate more resources to house construction, positioning a higher proportion of them above the poverty line. These outcomes align with broader research affirming the widespread benefits of remittances, encompassing improvements in health, education, household welfare, and access to essential resources. While our study underscores the positive impact of migration on the standard of living, it also recognizes the nuanced nature of this relationship. The complexity arises from varying contexts and circumstances, as indicated by counter-findings suggesting potential risks of increasing inequality between different segments of the population, particularly when remittances are concentrated among specific sections.
In the broader context of Kerala, our research aligns with the narrative of migration contributing to socio-economic improvements, particularly within deprived sections of households and communities. It resonates with existing literature emphasizing the dynamic role of migration in enhancing the income and social status of disadvantaged populations.
Ultimately, our study advocates for the recognition and strategic utilization of remittances and migration as potent tools for improving living standards. The direct influence of remittances, evident in higher expenditures on housing, and ownership of assets and consumer durables, signifies their role in elevating the standard of living and overall well-being. Thus, the positive impact of migration on the economic and living conditions of households in developing countries cannot be overlooked. Policymakers are urged to implement targeted interventions to maximize these benefits and to create a more equitable and inclusive society.
Footnotes
Acknowledgements
Authors cordially acknowledge the centre for development studies (CDS), Thiruvananthapuram, Kerala, India, for providing the Kerala Migration Survey (KMS) dataset to conduct this study.
Author Contributions
K. Afsal: Conceptualization, Methodology, Formal analysis, Supervision, Writing – Original Draft, and Review & Editing.
Muhammad Rishad: Conceptualization, Methodology, and Writing.
T. Muhammad: Conceptualization, Methodology, Supervision, Writing Validation, Review & Editing.
Dr. Reshmi R.S: Conceptualization, Methodology, and Writing.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical Approval
This study is based on a de-identified secondary available data and requires no further ethical approval from any institutional review board (IRB) to conduct this study. Informed consent is not applicable.
