Effect of public health expenditure on health outcomes in Nigeria and Ghana

Highlights

• •Our findings disclosed a low public health expenditure in both countries.
• •Ghana showed a negative relationship whilst Nigeria indicated a positive.
• •An increment in public health expenditure is purported for improving health outcomes.
• •The GDP and urban residence enhance health outcomes.

Abstract

Despite the prevailing literature examining the effect public health expenditure has on health outcomes in Africa, Malaria and HIV/AIDS mortality which are key indicators of the outcome variable were unconsidered when drawing inferences. In view of this oversight, we investigate the impact of public health expenditure on health outcomes in Nigeria and Ghana whilst reconceptualizing health outcome by capturing infant, maternal, Malaria and HIV/AIDS mortality. Using the health expenditure commitment at the 1999 United Nations General Assembly and the Abuja Declaration of 2000, we also assessed public policy’s role in this relationship via linear regression analysis. With hindsight, our findings disclosed a low public health expenditure in both countries despite the Ghanaian case revealing a negative relationship, which was primarily insignificant whilst Nigeria indicated a positive one. These empirical evidences accentuate the need to augment public health expenditure in both countries to boost health outcomes whilst bringing to bear the significant influence of GDP, school enrolment and residing in urban areas on health outcomes.

1. Introduction

Improving healthcare investment remains paramount in every nation’s development agenda, aligning with the sustainable development goal (SDG 3) of the United Nations [1]. Ensuring that everyone lives healthy is critical to sustainable development, as the recent COVID-19 global pandemic demonstrates how health crises can destabilise the economy and upend people’s lives. Before the emergence of COVID-19, many low-and-middle-income countries suffer from burden cases like Malaria and HIV/AIDS, which disrupted their daily lives and further decreased their productivity. By concentrating on more effective support for the health systems, strengthening the people’s access to healthcare and improving sanitation and hygiene, policymakers in these countries make substantial strides in reducing incidents such as child and maternal mortality [1]. In the year 2000, 147 of the world’s 189 countries, both wealthy and developing nations, gathered at the Millennium Summit to make a historic effort following the United Nations Millennium Declaration to achieve economic growth and poverty eradication within fifteen years (15 years). This pledge was encapsulated in the Millennium Development Goals (MDGs), which aimed at boosting human resources in areas such as poverty alleviation, health development, educational attainment, environmental protection, gender equality, and globalisation. These MDGs were summarised into eight goals which are: eradicate poverty and extreme hunger, achieve universal primary education, promote gender equality and empower women, reduce child mortality, improve maternal health, combat HIV/AIDS, Malaria and other diseases, ensure environmental sustainability and to develop a global partnership for development [2]. Adequate resources are required to achieve this aim, particularly in areas of health such as infant mortality, maternal health, HIV/AIDS, and Malaria. However, in the Sub-Saharan African (SSA) region, the financial resources needed for this development may not be sufficient.

To this end, the African leaders gathered in the year 2001 in what is today known as the Abuja Declaration to offer remarkable commitment towards improving health outcomes in the continent by increasing public health expenditure. The goal was to increase public health expenditure to 15% of the national budget by 2015. According to World Bank’s report in 2012, only six (6) African countries have been able to achieve this target, these countries include Rwanda (23%), Liberia (18.9%), Malawi (18.5%), Madagascar (15.5%), Togo (15.4%) and Zambia (16%) [3]. The economic giants within the continent like Nigeria, Ghana and South Africa are nowhere near this target. Based on this background, this study seeks to investigate how international public health policy influences public health expenditure and health outcomes in Nigeria and Ghana.

A significant proportion of the literature have examined the relationship between public health expenditure and health outcomes. Nixon & Ulmann [4] discovered that rising public healthcare investment is linked with significantly increases in child mortality in fifteen European Union (EU) countries from 1980 to 1995. Crémieux et al. [4] showed that lower healthcare spending is statistically significant to increase infant mortality in Canada. More recently, Ojapinwa et al. [5] revealed that public health expenditure had a negative effect on infant mortality in Nigeria. Novignon & Lawanson [3] found that public healthcare expenditure is positively and significantly related to infant mortality, under-five mortality and neonatal mortality. Most of the studies above focused more on developed countries, except for [2], [5] that paid attention to developing countries in their studies. In examining the relationship between public health expenditure and health outcomes, all the studies we reviewed restricted their health outcomes to infant and maternal mortality. Deaths caused by Malaria and HIV/AIDS are health outcomes of high prevalence in Sub Saharan Africa, which must not be overlooked, necessitating this study.

Malaria and HIV/AIDS are high burden epidemics in developing countries, especially in Sub-Sahara African countries. Beyond the individual illnesses and deaths caused by Malaria and HIV/AIDS, these outcomes have undermined the social structure in Sub-Saharan African countries. Evidence from other studies [6], [7], [8], [9] have shown the social, financial and economic cost of Malaria and HIV/AIDS-related illnesses and deaths. However, no research has explored the association between public health spending in Nigeria and Ghana, combining these four factors (infant mortality, maternal mortality, Malaria, and HIV/AIDS mortality) as key health outcomes. Thus, although the literature on the relationship between health expenditure and health outcomes in high-income countries exists, the operationalisation of health outcomes in developing countries is not exhaustive.

A critical gap identified from previous literature is the elimination of other vital variables in health outcomes such as Malaria and HIV/AIDS from this relationship in Sub-Sahara Africa. These two outcomes are high burden epidemics in Sub-Sahara African countries that must not be overlooked. In Nigeria and Ghana, no research has looked at the association between public health spending and child mortality, maternal mortality, Malaria, and HIV/AIDS mortality as health outcomes. Given this context, this research investigates the relationship between public health spending and public health results in Nigeria and Ghana, taking into account the position of public policy. Therefore, we asked the following questions:

• 1.What is the relationship between public health expenditure and health outcomes (infant mortality, maternal mortality, malaria mortality and HIV/AIDS mortality) in Nigeria and Ghana?
• 2.How would the United Nations General Assembly’s fulfilment of the MDGs (now known as the SDGs) and the Abuja Declaration affect health outcomes between 2000 and 2018?

In lieu of these questions, the following hypothesis was formulated:

Hypothesis 1

Increase in public healthcare expenditure would improve health outcomes (infant mortality, maternal mortality, malaria mortality and HIV/AIDS mortality).

Hypothesis 2

Public policy (Millennium Development Goals and Abuja Declaration) is significant for improving health outcomes in the region.

1.1. Study context

This study captures two areas in Sub-Saharan Africa, Nigeria and Ghana. We chose this sub-region and these countries due to the prevalence of adverse outcomes such as infant mortality, maternal mortality, HIV/AIDS and Malaria. The World Health Organization report (WHO, 2019) states that Africa accounts for 93% of the global malaria cases, the highest cases of HIV/AIDS, infant and maternal mortality compared to other areas of the world. Nigeria and Ghana are both in the West African region of the African continent. Nigeria accounts for almost half of West Africa’s population, with a population size estimated at around 202 million, making it the most populous African country (World Bank, 2020). The oil and gas sector accounts for almost ten per cent (10%) of the gross domestic product (GDP), whilst the revenue from oil accounts for eighty-six per cent (86%) of export revenue in Nigeria [10]. Despite the abundance of resources and massive revenue from crude oil, the impact of this has not reflected on the living condition of the populace, especially in the health sector. The World Bank posits that Malaria and HIV/AIDS continues to be a public health burden in Nigeria. For instance, of the six countries that account for half of the world’s malaria cases, Nigeria accounts for 25% of the total malaria burden [11]. UNAIDS states that HIV/AIDS is a prevalent public health problem within the country, affecting 1.9 million Nigerians [12]. It is for these reasons we selected Nigeria as one of our study areas.

On the other hand, Ghana has a population of 29.6 million people and a landmass of 238, 535 km² [13]. In recent times, Ghana has experienced significant growth in its economy; for instance, in 2019, the gross domestic product experienced an increase of 6.7%, projected to reach 7.6%. Oil, Gold and Cocoa account for a significant share of the country’s export revenue; revenue from these three exports resulted in a trade surplus of 2.8% of the country’s GDP [13]. Unfortunately, Ghana’s economic success has not also translated into better health conditions for the people. After twenty (20) years since the Abuja Declaration and United Nations Millennium Development Goals commitment, the country is yet to achieve 50% of the agreed targets. Cases of Malaria, HIV/AIDS, infant and maternal mortality still threatens the lives of the citizens. Reports from the World Health Organization shows that 100% of Ghana’s population are at risk of malaria infection, whilst infant and maternal mortality stand at 38.9 per 1000 births in 2015 and 319 per 100,000 deaths respectively in 2015 [14]. Despite these burdens, public health expenditure, when considered as a percentage of the GDP, has not experienced any significant shift from the early 2000s till this time. According to the World Bank, public health expenditure grew by only 0.48% from 2000 till 2015 [13]. Based on these troubling issues and the lack of literature on Ghana and Nigeria in the substantive issue, we purposively sampled both countries to be examined in this study.

2. Methodology

Following the literature reviewed, health expenditure as an indicator of the investment in healthcare is expected to improve health outcomes. This assumption is also in line with the work of Grossman [15]. According to Grossman, a positive change in investment will positively impact health outcome in any society. Thus, investment in public health spending in Nigeria and Ghana is expected to have a negative effect on infant and maternal mortality caused by malaria and HIV/AIDS. Furthermore, considering the redistributive influence of state interventions, a positive correlation is expected between public health expenditure and health outcomes in Nigeria and Ghana.

Following the standard evidence synthesis approach adopted by [16], this study’s inclusion criteria follow the PICOS principle. In addition to the adopted criteria, we added Study Period, which makes the inclusion criteria for this study PICOSS (Population, Intervention Policies, Comparison, Outcome, Setting, and Study Period). The target population for this study would be children and mothers. These populations were selected because they are the most affected by Malaria and HIV/AIDS in both countries. For this reason, we selected health outcome variables in terms of infants and maternal deaths. In addition, this study includes global and national public policies that affect the two study areas’ health sector. Two of which include the Abuja Declaration and the UN General Assembly’s commitment towards the MDGs, now known as the SDGs. These interventions are used to examine public policies’ role in the relationship between public health expenditure and health outcomes.

2.1. Variables and data sources

The health outcomes for consideration in this study include infant mortality, maternal mortality, malaria mortality, HIV/AIDS mortality. These factors were taken into account due to their high occurrence in the research locations. The aforementioned dependent variables were compared to public health spending, which we calculated as a share of GDP (GDP). The independent variable in this study is public healthcare expenditure. Other variables such as the GDP, female school enrolment and urban population were included as control variables for both countries. The research focuses on the Sub-Sahara Africa region. This study identified Sub-Sahara Africa because this region constitutes a large share of the global population. Coupled with this, it suffers from many burden health cases like Malaria and HIVAIDS, in addition to the extraordinary cases of infant and maternal mortality. From this region, Nigeria and Ghana are the two specific study areas considered for this study. These two countries were purposely selected for the following reasons: the size of their economy, and the share of the population-at-risk. For instance, 100% of Nigerians and Ghanaians are at risk of being infected by Malaria [17], [18], [19]. Based on those reasons, a comparative analysis of public health expenditure and health outcomes in developing countries is represented by Nigeria and Ghana. The period under examination is from 2000 to 2018. This period was chosen because it represents significant global events such as the Millennium Development Goals, currently known as the Sustainable Development Goals (SDGs) and the Abuja declaration in 2001. Both events focused on improving global and regional health. Secondly, the most recent data for both countries is limited to 2018 as at the time of investigation.

The type of data used by this study is the annual time series data from 2000 to 2018 collected from databases like the World Bank data bank (https://data.worldbank.org/), World Health Organization (https://www.who.int/gho/database/en/), and the International Health Metrics Evaluation (IHME) (https://www.healthdata.org/). The data collected focused on public health expenditure, health outcomes (infant mortality, maternal mortality, malaria mortality and HIV/AIDS mortality), and control variables such as GDP, female school enrolment and urban population. These variables align with the MDGsand, most recently, the Sustainable Development Goal 3.0. These sets of variables were used to examine the relationship between public health expenditure and health outcomes. This study applied linear interpolation to input the missing data for each of the variables mentioned above (maternal mortality, malaria mortality, HIV/AIDS mortality, and public health expenditure). Descriptive statistics such as mean and standard deviations were used as univariate techniques to describe the data. The independent variable was represented by public health expenditure which was captured as a share of the GDP. The dependent variables are defined by the selected health outcomes for this study (infant and maternal mortality, mortalities caused by Malaria and HIV/AIDS). Finally, SPSS was used to carry out a linear regression analysis to examine the relationship, and the effect of public health expenditure on health outcomes in Nigeria and Ghana.

In this study, health outcomes were proxied by infant mortality, maternal mortality, Malaria, and HIV/AIDS morbidities. Health expenditure data is expressed as a share of the total government’s expenditure for both countries. The variables were controlled with GDP, female school enrolment and urban population. This is because these variables are likely to be correlated with public health expenditure.

3. Result

Nigeria and Ghana experienced a reducing infant mortality rate (IMR) trend from 2000 to 2018 (Appendix 1). Ghana recorded an average of 49.0 deaths per 1,000 live births (infant mortality rate), with Nigeria almost doubling this figure with an average of 89.14 deaths per 1,000 live births over the same period. Concerning the maternal mortality rate, both countries experienced a downward trend over the study period (2000 – 2018) (Appendix 2). However, maternal mortality rates in these two countries remain relatively high. However, compared to Nigeria, Ghana reported a relatively low rate of 357.9 per 100,000 deaths. On the other hand, Nigeria has a sky-high maternal mortality rate, with an average of 1025.37 per 100,000 deaths.

Nigeria and Ghana offer an exciting direction in malaria mortality, with Ghana reporting a higher malaria death than Nigeria. The result indicates that Malaria caused an average of 133.9 and 113.5 deaths per 100,000 deaths in Ghana and Nigeria (Appendix 3). For HIV/AIDS mortality, it displayed downward slopes from the year 2008 with peak years for both countries in 2007 at 13% and 11.4% of total deaths for Nigeria and Ghana (Appendix 4). Nigeria, on the other hand, exhibits a gradual declining trend, falling from 12.8% in 2008 to 10.4% in 2018, while Ghana fell from 11.1% in 2008 to 6.5% in 2018 (Appendix 4). Finally, although the figures showed an increasing trend for public health expenditure, public health expenditure for both countries remained low at an average of 3.7% and 3.8% as a share of GDP (Appendix 5). This indicates that the governments of both countries need to scale up health expenditure. The mean of the following variables; infant mortality is 89.14 per 1,000 births for Nigeria and 49.03 for Ghana; maternal mortality is 1025 and 357.9 per 100,000 deaths for Nigeria and Ghana. Therefore, the mean mortality rate caused by malaria was 108.7 per 100,000 deaths for Nigeria and 127. 6 per 100,000 deaths for Ghana (Appendix 6 and 7). Simultaneously, the mean for HIV/AIDS mortality for Nigeria and Ghana is 11.68% and 9.65% (Appendix 6 and 7).

The health expenditure and health outcome relationship results are presented in Table 1, Table 2, Table 3, Table 4 for HIV/AIDS mortality, malaria mortality, infant mortality, and maternal mortality. The results from the alternative specifications used to test the model’s robustness are also reported in the tables. Furthermore, we conducted a simulation analysis to test the impact of the public health expenditure on health outcomes by assuming both countries increased health expenditure to 15% of GDP (Appendix 8 to 11). In the simulation, we assumed that both countries increased public health expenditure by 1% annually to the point where public health expenditure was at 15%. Afterwhich, we estimated the relationship between public health expenditure and health outcomes in both countries. In addition, the simulation assumes that both countries implemented the 15% public health expenditure budget as agreed in the United Nations Assembly and the Abuja Declaration in 1999 and 2000 [20].

Table 1.

Regression analysis for public health expenditure and HIV/AIDS for Ghana and Nigeria.

	Variables	Ghana					Nigeria
Pearson Correlation		(1)	(2)	(3)	(4)	(5)	(1)	(2)	(3)	(4)	(5)
	HIV/AIDS Mortality		−0.059	−0.917	−0.854	−0.854		0.323	0.201	0.201	0.015
	Public Health Expenditure			0.364	0.423	0.423			0.201	0.201	−0.090
	GDP				0.981	0.981				−0.329	0.950
	Female School Enrolment					0.924					−0.493
	Urban Population
Sig. (1-tailed)	HIV/AIDS		0.405	0.000	0.000	0.000	.	0.089	0.159	0.204	0.476
	Public Health Expenditure as a Percentage of GDP	0.405	.	0.063	0.001	0.035	0.089	.	0.338	0.205	0.357
	GDP	0.000	0.063	.	0.000	0.000	0.159	0.338	.	0.085	0.000
	Female School Enrolment	0.000	0.001	0.000	.	0.000	0.204	0.205	0.085	.	0.016
	Urban Population

Table 2.

Regression analysis for public health expenditure and malaria mortality for Ghana and Nigeria.

	Variables	Ghana					Nigeria
Pearson Correlation		(1)	(2)	(3)	(4)	(5)	(1)	(2)	(3)	(4)	(5)
	Malaria Mortality		−0.063	−0.905	−0.722	−0.855		0.185	−0.848	0.540	−0.958
	Public Health Expenditure			0.364	0.643	0.423			−0.103	0.201	−0.090
	GDP				0.899	0.981				−0.329	0.950
	Female School Enrolment					0.924					−0.493
	Urban Population
Sig. (1-tailed)	Malaria		0.400	0.000	0.000	0.000		0.224	0.000	0.008	0.000
	Public Health Expenditure as a Percentage of GDP			0.063	0.001	0.035			0.338	0.205	0.357
	GDP				0.000	0.000				0.085	0.000
	Female School Enrolment					0.000					0.016
	Urban Population

Table 3.

Regression analysis public health expenditure and infant mortality for Ghana and Nigeria.

	Variables	Ghana					Nigeria
		(1)	(2)	(3)	(4)	(5)	(1)	(2)	(3)	(4)	(5)
Pearson Correlation	Infant Mortality		−0.422	−0.983	−0.920	−0.999		0.048	−0.982	0.437	−0.972
	Public Health Expenditure			0.364	0.643	0.423			−0.103	0.201	−0.090
	GDP				0.899	0.981				−0.329	0.950
	Female School Enrolment					0.924					−0.493
	Urban Population
Sig. (1-tailed)	Infant Mortality		0.036	0.000	0.000	0.000		0.423	0.000	0.031	0.000
	Public Health Expenditure			0.063	0.001	0.035			0.338	0.205	0.357
	GDP				0.000	0.000				0.085	0.000
	Female School Enrolment					0.000					0.016
	Urban Population

Table 4.

Regression analysis for public health expenditure and maternal mortality for Ghana and Nigeria.

	Variables	Ghana					Nigeria
		(1)	(2)	(3)	(4)	(5)	(1)	(2)	(3)	(4)	(5)
Pearson Correlation	Maternal Mortality		−0.550	−0.834	−0.866	−0.912		0.076	−0.966	0.450	−0.954
	Public Health Expenditure			0.364	0.643	0.423			−0.103	0.201	−0.090
	GDP				0.899	0.981				−0.329	0.950
	Female School Enrolment					0.924					−0.493
	Urban Population
Sig. (1-tailed)	Maternal Mortality		0.007	0.000	0.000	0.000		0.379	0.000	0.027	0.000
	Public Health Expenditure			0.063	0.001	0.035			0.338	0.205	0.357
	GDP				0.000	0.000				0.085	0.000
	Female School Enrolment					0.000					0.016
	Urban Population

Table 1 is a bivariate relationship between public health expenditure as a share of GDP and HIV/AIDS mortality for Ghana and Nigeria. The relationship shows to be negative for Ghana, although the effect of public health expenditure is not statistically significant. The result implies that a percentage increase in Ghana’s public health expenditure would reduce HIV/AIDS mortality by 0.1% on average. However, in the case of Nigeria, as seen in Table 1, it contradicts the result in Ghana. The relationship between public health expenditure and HIV/AIDS mortality in Nigeria appears to be positive. It implies that when public health expenditure increases by 1%, HIV/AIDS mortality also increases by 0.3%. When controlled for GDP, female school enrolment and urban populations, the result suggests that increasing public health expenditure reduces HIV/AIDS deaths by approximately 0.9% in Ghana. For Nigeria, the case remains the same (positive correlation). When public health expenditure was assumed to maintain a 16.4% average based on the simulation, between 2000 and 2018 in both countries, the relationship became negative. However, the effect was more significant in Ghana than in Nigeria, as seen in Table 1. The simulation implies that both countries’ public health expenditure is deficient. This means it lacks the strength to reduce HIV/AIDS mortality significantly. Secondly, out-of-pocket expenditure is very high in both countries. This may be the likely reason for the improvement that we see in the trend analysis for both countries. Third, the simulation results show that fulfilling the UN Assembly’s and Abuja Declaration’s pledged 15% public health expenditure is critical to reducing the HIV/AIDS burden in both countries.

Public health expenditure showed a negative relationship with malaria deaths in Ghana but not in Nigeria (See Table 2). This suggests that increasing the public health expenditure budget as a proportion of GDP by 1% would reduce Ghana’s malaria deaths by 0.063%, which is very insignificant. After adjusting for other factors such as GDP, school enrollment, and urban population, the results indicate that increasing public health spending by 1% decreases malaria mortality in Ghana by around 0.91%, 0.72%, and 0.9%, respectively. This case is also similar in Nigeria; however, only GDP and urban population could reduce malaria mortality after increasing public health expenditure by 1%. After simulating, public health expenditure was an average of 16.4% between 2000 and 2018. The relationship between public health expenditure and malaria mortality negatively correlated. This is an implication that public health is deficient in both countries, especially Nigeria. Hence, both countries would have to increase public health expenditure to at least 15% of the total government’s expenditure to observe any significant impact.

Table 3 depicts the infant mortality scenario for both countries; for Ghana, the direct association between public health expenditures and infant mortality conforms with the current theory, but only when GDP is taken into account. When controlled for GDP and urban population, the relationship becomes negative in Nigeria. Increasing public expenditure based on the simulations for Ghana and Nigeria reduces the infant mortality rate in both countries without controlling variables. However, after controlling for these variables, the estimate significantly reduces. For example, in Nigeria, the infant mortality rate improves from −0.42% to 0.98% when controlled before simulation. After simulation, it improves from 0.97% to 0.98% after controlling for GDP.

Table 4 represents the public health expenditure–maternal mortality relationship for Ghana and Nigeria, respectively. Public expenditure on maternal mortality showed a negative relationship for Ghana and positively related in Nigeria. However, controlling for other variables (GDP and Urban population) indicated a significant effect of public health expenditure on maternal mortality in Nigeria. For Ghana, the relationship between public health expenditure and maternal mortality remains negative and statistically significant. While controlling for female school, enrolment could not improve the relationship between public expenditure and maternal mortality in Nigeria.

4. Discussion

As illustrated in this study, measuring the relationship between health expenditure and health outcomes is a complex issue. Health expenditure and health outcomes relationship are usually analysed from two angles: micro or macro perspectives. Our analysis followed the macro perspectives by estimating the effect of government health expenditure as a share of GDP on health outcomes in Nigeria and Ghana. First, we estimated the relationship between public health expenditure in Nigeria and Ghana and health outcomes from 2000 to 2018. In this study, the health outcomes were represented as discrete dependent variables rather than as a composite health outcome variable. This study’s health outcomes included infant and maternal mortality, malaria, and HIV/AIDS mortality. The inclusion of these two outcomes (malaria and HIV/AIDS mortality) distinguishes this study. Based on the literature review, no previous studies have combined these four variables (infant mortality, maternal mortality, malaria mortality, and HIV/AIDS mortality) even though malaria and HIV/AIDS mortality are two critical health outcomes in Sub-Sahara Africa.

Public health expenditure on health outcomes was estimated by controlling for GDP, female school enrolment and urban population. Secondly, we conducted a simulation analysis of this relationship to see the effect health expenditure will have on health outcomes in Nigeria and Ghana if health expenditure rose to 15%. The simulation was run on the premise that public health expenditure grew by 1% every year from 2000 through the point when it reached 15% in both nations, which was in 2011 for Nigeria and 2012 for Ghana. The simulation is an assumption that both countries implemented the 15% public health expenditure budget as agreed in the United Nations Assembly and the Abuja Declaration in the year 1999 and 2000, respectively.

The standard estimated result demonstrated that the relationship between public health expenditures and health outcomes in Ghana was consistent with previous studies [2], [3], [14] across all dependent variables in this investigation. Although, some of the results were not statistically significant. However, after controlling for factors like GDP, female school enrolment and urban population, the impact of public health expenditure on health outcomes improved in Ghana, but not in all situations for Nigeria. This implies that health expenditure alone is not enough to improve the health of citizens, but the inclusion of other factors such as residing in an urban region or level of educational attainment also affect the health of citizens [20]. However, these results also demonstrate that health disparities will persist between persons of different socioeconomic classes and between residents of rural and urban neighbourhoods. Several studies in developed and developing countries have found that people who live in cities have better health outcomes than those residing in rural areas, owing to the greater access to quality healthcare in cities. For instance, research conducted in the United States by [21] found that infant mortality rates decreased as the level of urbanisation increased. Among developing countries, [22] reported that socioeconomic and demographic disparities between rural and urban households translate to infant and maternal mortality disparities. [23] also found that the level of intervention for burden health cases also differ across rural and urban areas in developing countries because of poor access. Even within urban communities, [24] identified health disparities between less and higher urban cities. Beyond socioeconomic and demographic disparities, poor access to basic amenities were also factors resulting in the health disparities. This means that, in order to see significant gains in health outcomes, the government must spend heavily on infrastructure such as hospitals, decent roads to guarantee geographical accessibility, and increased school enrolment, especially in elementary and secondary schools in both rural and urban regions. This is consistent with Grossman’s demand for health model, which states that investing in health entails investing in medical treatment, time, and human resources [25].

Conversely to Ghana, the relationship between public health expenditure and health outcomes were positively correlated across all variables in Nigeria. It even remained unchanged for some variables after controlling for GDP, school enrolment, and urban population. These results contradict Grossman’s health investment model [15]. Several factors may come into play for such results in Nigeria. First, given the large population in Nigeria compared to the relatively low health expenditure, the per capita healthcare expenditure is meagre. The latest data from the World Bank shows that per capita health expenditure in Nigeria was $US84 in 2018, compared to the world average of US$1,111 [26]. Even after holding other factors (for example, GDP) constant, the relationship between health expenditure and HIV/AIDS mortality remained unchanged. This shows that the amount of government expenditure on health was not primarily responsible for the death reduction due to HIV/AIDS and malaria and child and maternal mortality that was experienced between 2000 and 2018. However, this study did not include aids from foreign donors due to data inconsistencies in both countries. The reductions in health outcomes, especially for HIV/AIDS and malaria mortality in Nigeria, as reported in the result from 2000 to 2018, are likely to result from foreign support through aids from international and domestic donors, such as charity organisations, international organisations and rich countries. According to evidence, Nigeria was the greatest recipient of health development funding in 2017 and 2018 [27], [28], [29]. Secondly, issues of corruption is another problem with governance and public funds in Nigeria. In addition to the relatively low government health expenditure, cases of looting and diversion of public funds for personal use occurs across every sector of the country which can have implications on the performance of the health sector. For instance, the recent corruption index places Nigeria at 149/180 in 2020 [30]. Ojapinwa [5] found that public health expenditure in Nigeria had a negative effect on health outcomes when governance indicator, which was represented by corruption was included in the analysis. Furthermore, the presence of technology in healthcare is another factor that could help to reduce the rate of mortality; however, that was not captured in this analysis. Several studies in developing countries, including Nigeria, have found that technology through e-health services can reduce infant and maternal mortality by improving access to quality healthcare [14], [31], [32].

In summary, at first glance, the tables (Table 1, Table 2, Table 3, Table 4) suggest a different effect of public health expenditure on the different health outcomes. One interesting aspect might be that public health investment in these countries is insufficient and may not be directed towards interventions that address these concerns, such as HIV/AIDS, Malaria, infant and maternal mortality. The expenditure may simply be used to finance salaries of medical personnels and other administratives functions. Secondly, another compelling reason might be the effect of out-of-pocket (OOP) expenditure, which seems very high in these countries. For instance, in Nigeria, out-of-pocket health expenditure accounts for 77.2% of total health expenditure in 2017 [33]. Thirdly, these two countries rely heavily on foreign aids; these may be another factor that would affect these relationships. Future studies may examine if these two factors (OOP and foreign aid) drive the inconsistencies in the relationship between public health expenditure and health outcomes. It will be essential to see whether including out-of-pocket expenditure and foreign aid provides a more robust regression estimate. Also, the large population of Nigeria estimated at 202 million people in 2019 may be a reason for the consistent variations observed between Ghana and Nigeria compared to Ghana’s 29.6 million people [13].

4.1. Study limitation

Like many other studies, this study was not without limitations. The primary limitation of this study was majorly in its availability of consistent data for out-of-pocket expenditure (OOP), foreign aids and data on technology involvement. If data for these three variables were available in these countries at the time of this study, it would allow for a more comprehensive evaluation of health spending on health outcomes, particularly in Nigeria. Future studies can examine this relationship by incorporating OOP, foreign aids, and technology into the dataset depending on the data availability. Also, this analysis ended in 2018, which was the latest available data for both countries. Future research may extend the scope of this study to include the current day and examine whether there have been any changes in government health spending and their effects on health outcomes.

5. Conclusion

According to the findings of this study, public health spending in itself is not enough to reduce health burdens, particularly for countries with low public health expenditure. The proportion of total government expenditure spent on healthcare in both countries is deficient in combatting infant, maternal, Malaria and HIV/AIDS mortalities. The simulation conducted by this study has revealed that increasing public health expenditure by 1% annually up to at least 15% can significantly reduce health outcomes. This study has shown that fulfilling the UN General Assembly (MDG/SDG) and the Abuja Declaration commitment is critical to resolving these over dragging issues. Other factors, like GDP, school enrolment and residing in urban areas, also determine the prevalence of health outcomes. Many rural areas in low- and middle-income nations such as Nigeria and Ghana lack access to health care services, which is essential for optimal health.

CRediT authorship contribution statement

Oladosu Ayomide Oluwaseyi: Conceptualization, methodology, formal analysis, writing - original draft. Timothy Chanimbe: Conceptualization, Writing - review & editing. Uchechi Shirley Anaduaka: Conceptualization, validation.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A. Supplementary material

The following are the Supplementary data to this article: