Acharya, S., Ghimire, S., Jeffers, E. M., & Shrestha, N. (2019). Health care utilization and health care expenditure of Nepali older adults. Frontiers in Public Health, 7(24), 1–10.

Google Scholar 

Aday, L. A., & Andersen, R. M. (1974). A framework for the study of access to medical care. Health Services Research, 9, 208–220.

Google Scholar 

Adetsav, A. O. S. (2016). Out-of-pocket expenditures, equity in equity in maternal health care utilization and health outcomes in Nigeria. Dissertation. Kenya: Kenyatta University.

Adisa, O. O. (2016). The determinants and consequences of economic vulnerability among urban elderly Nigerians. Dissertation. United Kingdom: University of Nottingham..

Adisa, O. (2015). Investigating determinants of catastrophic health spending among poorly insured elderly households in urban Nigeria. International Journal for Equity in Health, 14(79), 1–11.

Google Scholar 

Adisa, O. (2019). Why are some older person economically vulnerable and others not? The role of socio-demographic factors and economic resources in the Nigerian context. Ageing International, 44, 202–222.

Article  Google Scholar 

Akazili, J., Garshong, B., Aikins, M., Gyapong, J., & McIntyre, D. (2012). Progressivity of health care financing and incidence of service benefits in Ghana. Health Policy and Planning, 27, i13–i22.

Article  Google Scholar 

Akin, J., Birdsall, N., de Ferranti, D. (1987). Financing health services in developing countries: an agenda for reform. 1987 World Bank Policy Study. The World Bank.

Google Scholar 

Aregbeshola, B. S., & Khan, S. M. (2018a). Out-of-pocket payments, catastrophic health expenditure and poverty among households in Nigeria 2010. International Journal of Health Policy and Management, 7(9), 798–806.

Article  Google Scholar 

Aregbeshola, B. S. (2017). Enhancing political will for universal health coverage in Nigeria. MEDICC Review, 19(1), 42–46.

Article  Google Scholar 

Aregbeshola, B. S., & Khan, S. M. (2018b). Predictors of enrolment in the National Health Insurance Scheme among women of reproductive age in Nigeria. International Journal of Health Policy and Management, 7(11), 1015–1023.

Article  Google Scholar 

Aregbeshola, B. S., & Khan, S. M. (2021). Out-of-pocket health-care spending and its determinants among households in Nigeria: A national study. Journal of Public Health: from Theory to Practice, 29, 931–942.

Article  Google Scholar 

Belotti, F., Deb, P., Manning, W. G., & Norton, E. C. (2015). twopm: Two-part models. Symposium (international) on Combustion, 15(1), 3–20.

Google Scholar 

Brinda, E. M., Kowal, P., Attermann, J., & Enemark, U. (2015). Health service use, out-of-pocket payment and catastrophic health expenditure among older people in India: The WHO study on global AGEing and adult health (SAGE). Journal of Epidemiology and Community Health, 69(5), 489–494.

Article  Google Scholar 

Brinda, E. M., Rajkumar, A. P., Enemark, U., Prince, M., & Jacob, K. S. (2012). Nature and determinants of out-of-pocket health expenditure among older people in a rural Indian community. International Psychogeriatrics, 24(10), 1664–1673.

Article  Google Scholar 

Crystal, S., Johnson, R. W., Harman, J., Sambamoorthi, U., & Kumar, R. (2000). Out-of-pocket health care costs among older Americans. Journals of Gerontology. Series b, Psychological Sciences and Social Sciences, 55(1), S51-62.

Article  Google Scholar 

De Nardi, M., French, E., Bailey, J., & MacCauley, J. (2016). Medical Spending of US Elderly Fiscal Studies, 37(3–4), 717–747.

Article  Google Scholar 

Goldman, D. P., & Zissimopoulous, J. M. (2003). High out-of-pocket health care spending by the elderly. Health Affairs, 22(3), 194–202.

Article  Google Scholar 

Gottret, P., & Schieber, G. J. (2006). Health financing revisited: A practitioner’s guide. The World Bank.

Book  Google Scholar 

Grossman, M. (1972). On the concept of health capital and the demand for health. The Journal of Political Economy, 8(2), 223–255.

Article  Google Scholar 

Grossman, M. (2000) The human capital model. In: Handbook of health economics. 1. Elsevier, pp. 347–408.

Heckman, J. J. (1979). Sample selection bias as a specification error. Econometrica, 47(1), 153–161.

Article  Google Scholar 

HelpAge International. (2015). Global AgeWatch Index 2015: Insight report. http://www.helpage.org/global-agewatch/reports/global-agewatch-index-2015-insight-report-summary-and-methodology/. Accessed October 6, 2020

Kimalu, P. (2013). Household health expenditure and health outcomes in Kenya. Dissertation. Kenya: Kenyatta University.

Kowal, P., Dowd, J. E. (2001). Definition of an older person. Proposed working definition of an older person in Africa for the MDS Project. Geneva: World Health Organization.

Leung, S. F., & Yu, S. (1996). On the choice between sample selection and two-part models. Journal of Economics, 72, 197–229.

Article  Google Scholar 

Lu, C., Chin, B., Li, G., & Murray, C. J. L. (2009). Limitations of methods for measuring out-of-pocket and catastrophic private health expenditures. Bulletin of the World Health Organization, 87, 238–244.

Article  Google Scholar 

Masiye, F., & Kaonga, O. (2016). Determinants of healthcare utilisation and out-of-pocket payments in the context of free public primary healthcare in Zambia. International Journal of Health Policy and Management, 5(12), 693–703.

Article  Google Scholar 

Mills, A., Ataguba, J. E., Akazili, J., et al. (2012). Equity in financing and use of health care in Ghana, South Africa, and Tanzania: Implications for paths to universal coverage. The Lancet, 380, 126–133.

Article  Google Scholar 

Mohanty, S. K., Chauhan, R. K., Mazumdar, S., & Srivastava, A. (2014). Out-of-pocket expenditure on health care among elderly and non-elderly households in India. Social Indicators Research, 115(3), 1137–1157.

Article  Google Scholar 

National Bureau of Statistics. (2018). 2017 demographic statistics bulletin. Abuja: National Bureau of Statistics.

National Bureau of Statistics. (2020). 2019 poverty & inequality in Nigeria report: Executive Summary. Abuja: National Bureau of Statistics.

National Bureau of Statistics. (2022). The 2022 multidimensional poverty index report. Abuja: National Bureau of Statistics.

Odeyemi, I. A. O., & Nixon, J. (2013). Assessing equity in health care through the national health insurance schemes of Nigeria and Ghana: A review-based comparative analysis. International Journal of Equity in Health, 12(9), 1–18.

Google Scholar 

Olasehinde, N., & Olaniyan, O. (2017). Determinants of household health expenditure in Nigeria. International Journal of Social Economics, 44(12), 1694–1709.

Article  Google Scholar 

Onoka, A. O., Hanson, K., & Hanefeld, J. (2016). Towards universal health coverage: A policy analysis of the development of the National Health Insurance Scheme in Nigeria. Health Policy and Planning, 30(9), 1105–1117.

Article  Google Scholar 

Onwujekwe, O. E., Uzochukwu, B. S. C., Obikeze, E. N., Okoronkwo, I., Ochonma, O. G., Onoka, C. A., et al. (2010). Investigating determinants of out-of-pocket spending and strategies for coping with payments for health care in Southeast Nigeria. BMC Health Services Research, 10(67), 1–10.

Google Scholar 

Opondo, E. M., & Oleche, M. O. (2020). Out-of-pocket health expenditure among the elderly in Kenya. Global Journal of Health Science., 12(11), 1–12.

Article  Google Scholar 

Oyinpreye, A. T. G., & Moses, K. T. (2014). Determinants of out-of-pocket health care expenditure in south-south geo-political zone of Nigeria. International of Journal of Economics, Finance and Management, 3(6), 296–300.

Google Scholar 

Tanyi, P. L., Andre, P., & Mbah, P. (2018). Care of the elderly in Nigeria: Implications for policy. Congent Social Sciences, 4(1555201), 1–14.

Google Scholar 

United Nations. (2015). Transforming our world: The 2030 agenda for sustainable development. https://sustainabledevelopment.un.org/post2015/transformingourworld/publication. Accessed October 6, 2020.

Vyas, S., & Kumaranayake, L. (2006). Constructing socio-economic status indices: How to use principal components analysis. Health Policy and Planning, 21(6), 459–468.

Article  Google Scholar 

World Health Organization. (2005). Sustainable health financing, universal coverage and social health insurance: World Health Assembly Resolution WHA 58.33. Geneva: World Health Organization.

Wealth Health Organization. (2010). The World Health Report 2010: Health Systems Financing: The Path to Universal Coverage. World Health Organization.

Google Scholar 

World Health Organization. (2014a). World Health Statistics 2014. World Health Organization.

Google Scholar 

World Health Organization. (2014b). World Malaria Report. World Health Organization.

Google Scholar 

World Health Organization. (2015). World Health Statistics 2015. World Health Organization.

Google Scholar 

World Health Organization. (2016a). Public financing for health in Africa: From Abuja to the SDGs. World Health Organization.

Google Scholar 

World Health Organization. (2016b). World Health Statistics 2016: Monitoring health for the SDGs. World Health Organization.

Google Scholar 

World Health Organization. (2018a). World health statistics 2018: Monitoring health for the SDGs. World Health Organization.

Google Scholar 

World Health Organization. (2018b). National Health Account: Nigeria. Geneva: World Health Organization. https://knoema.com/WHONHA2018Feb/national-healthaccounts?country=1000340-nigeria. Accessed October 6, 2020.

World Health Organization. (2023). World Health Statistics 2023: Monitoring health for the SDGs, sustainable development goals. World Health Organization.

Google Scholar 

World Health Organization, World Bank. (2019). Global monitoring report on financial protection in health 2019. Switzerland: World Health Organization and World Bank.

Xu, K., Evans, D. B., Carrin, G., Aguilar-Rivera, A. M., Musgrove, P., & Evans, T. (2007). Protecting households from catastrophic health spending. Health Affairs (Millwood), 26(4), 972–983.

Article  Google Scholar 

Xu, K., Evans, D. B., Kawabata, K., Zeramdini, R., Klavus, J., & Murray, C. J. L. (2003). Household catastrophic health expenditure: A multi-country analysis. The Lancet, 362, 111–117.

Article  Google Scholar