Low and middle income countries (LMICs) support 84% of the global population, comprise 90% of the global disease burden and yet, account for only 12% of global resources spent on health . Public expenditures on health, as a share of their Gross Domestic Product (GDP) are significantly less in LMICs [2, 3]. Most of the health expenditures are paid directly as out-of-pocket (OOP) payments . LMICs also experience overlapping health transition with the additional burden of both infectious and chronic diseases.
The vast majority of African countries rely on direct OOP health expenditures and experiences a high burden of catastrophic health expenditures [6–8]. Tanzania with its growing ageing population, supports a current older population (60 years and above) of 1.5 million, which is projected to increase to 3 million by 2025 . Tanzania spends a low share of GDP (7.2% ) on health, with a meagre public expenditure of 39% of the total health costs . The OOP health expenditures account for 52% of total health spending, while various public and private pre-payment schemes contribute the remaining expenditures . User fees at public health facilities were introduced in Tanzania in the 1990s with the intention of mobilizing resources and providing sustainable healthcare . However, ineffective exemption systems, ancillary health care costs of the health seekers through transportation, food and accommodation escalates the high OOP health expenditures . Health care seeking through private healthcare and faith-based health facilities or traditional healers contributes to most of the health service utilization . These providers charge user fees, have some waiver system and do not provide exemptions .
Affordability  and accessibility  determine health service utilization in many LMICs. The use of essential health services are reported to be avoided by poor people with the increasing demand for OOP health expenditures [16, 17]. Andersons’ behavioral model aids the theoretical understanding of the nature of health service utilization and subsequent OOP health expenditures in LMICs [3, 18]. High OOP health expenditures have a serious impact on vulnerable people who subsequently experience debt, income loss and catastrophic health expenditures [7, 19]. Health expenditures are regarded catastrophic, when they exceed 40% of household’s effective income remaining after subsistence needs .
Knowledge about the determinants of OOP expenditure on health is vital from a health policy perspective, to inform the design of interventions or system changes that ensure accessible and financially protective health services to vulnerable people. The studies on determinants of OOP health expenditure in various LMICs are primarily focused on adult populations. The research findings cannot necessarily be extrapolated to older people who differ in disease patterns , health-seeking behaviors  and access to resources in LMICs . Moreover, the relative absence of social welfare policies and inequitable access to health services require the specific assessment of OOP health expenditures prevalent in LMICs [4, 23]. Hence, we aim to investigate the determinants influencing OOP health expenditures among the adult as well as the older population aged above 60 years in Tanzania. We also intend to explore the determinants of catastrophic health expenditures based on Tanzanian households’ non-food expenditures.