Non-communicable diseases (NCDs) such as stroke, cancer, malaria, amongst others, contribute in no small measure to mortality and morbidity worldwide [1]. They comprise much of the world’s disease burden [2, 3]. However, there is ample evidence to show that NCDs are experienced differently across geographical, ethnic, and racial lines. For instance, 80% of mortality from NCDs occur in low- and middle-income countries (LMICs) [4]. Whilst the burden of NCDs in sub-Saharan African regions is higher than the global average and is now almost equivalent to the total burden associated with Communicable, Maternal, Neonatal, and Nutritional [CMNN] diseases [5]. Studies show that migrant and non-migrant experiences of diseases could differ, given prevailing social, cultural, political, and economic conditions [6, 7]. South Africa is the most significant destination point for migrants in Africa. It is reported by the International Organisation for Migration (IOM) that the country has over 4 million international migrants [8]. The implication of the much inflow of immigrants into South Africa could manifest in disease experiences, hence the need to investigate such implication regarding NCDs.
The internal movement of people across different provinces in South Africa and the net flows of in- and out-migration across the provinces have consequences on the prevalence and risk behaviors associated with non-communicable diseases [6]. These inter-provincial migrants are bound to face several circumstances while in transit and at destination. Issues of adaptation to ecological, economic, policy, political, and social circumstances are foremost, and could influence disease experiences [9]. Some of the migrants are exposed to health hazards along their journeys and might have difficulties accessing healthcare for policy reasons [7]. These risk factors as highlighted can cause these inter-provincial migrants to experience NCDs differently. Unfortunately, the issues of internal migration and NCDs have remained underexplored in literature, compared to the attention that is given to migrants’ and non-migrants’ experiences of infectious diseases like tuberculosis and HIV/AIDS [10].
The four most common NCDs are cardiovascular disease (CVDs), including heart attack and stroke; cancers; chronic respiratory disease, including chronic obstructive pulmonary disease and asthma; and diabetes [1]. They are caused by a combination of modifiable and non-modifiable risk factors, including genetic, metabolic, behavioral and environmental factors [1]. It has been noted that the global epidemic of NCDs constitutes a public health emergency in slow motion [11]. Hence, in September 2011, at a United Nations high-level meeting on NCDs, heads of state and government formally recognized these diseases as a major threat to economies and societies and placed them high on the development agenda (2014). Subsequently, the World Health Organization (WHO) initiated a plan of action aimed at globally reducing mortality from cardiovascular disease, cancer, diabetes and chronic respiratory diseases by 25% before 2025 [12].
Literature show that South Africa grapple with “quadruple” burden of disease which are high level of HIV/AIDS, infectious diseases such as tuberculosis, high level of mortality and morbidity due to injuries and high levels of non-communicable disease (NCDs) [13]. Specifically, non-communicable diseases accounted for 43% of total deaths in all ages and sexes in South Africa in 2012 while the probability of dying between the ages 30–70 years due to NCD was 27% [12]. Evidence also shows that the burden of NCDs has increased over the past 15 years, resulting in an estimated 37% of all-cause mortality and 16% of disability adjusted life years [14].
The increased prevalence of NCDs in South Africa have been attributed to four lifestyle risk factors of poor diet, physical inactivity, tobacco use and inappropriate use of alcohol [15, 13]. In examining the differences in non-communicable disease risk factors in middle-income countries. [10] observed that alcohol consumption, patterns of smoking, physical activities are risk factors for NCDs. [16] equally reported the prevalence and variations in tobacco and alcohol use among migrants and non-migrant youths in South Africa. Migration has also been identified as a risk factor in the NCD epidemic, people migrate to urban or rural areas in search of greener pastures and this leads to changes in their lifestyle which may make them vulnerable to NCDS [15]. Changes in lifestyle behaviours accompanying migration are exemplified primarily by shifts in physical activity and dietary patterns which promote the development of obesity, diabetes, hypertension and cardiovascular diseases [17]. It has also been observed that nutritional patterns among migrants particularly in urban centres change rapidly with a shift to diets higher in fat, sugar and salt which have implications for NCDs [17]. In addition, understanding how urbanization and rural-urban migration influence risk-factors for noncommunicable disease (NCD) is crucial for developing effective preventative strategies [10].
Studies have shown disparities in socioeconomic status, across provinces and districts, and most importantly, between urban and rural areas as well as between migrants and non-migrants in South Africa [18–20] Sex differences in CVDs resulting from sociocultural processes, such as differences in behaviors of women and men, different dietary habits, lifestyles or stress, and different attitudes toward treatments and prevention has been reported [21]. A recent study of inequalities among South Africans found that gender differences in NCDs was mainly accounted for by differences in characteristics rather than behavioral responses [22]. However, [22] observed that gender-based inequalities in NCDs are a stark reality in South Africa. It has been noted that sex differences in NCD risk factors need to be considered when evaluating one’s probability of developing NCD [23]. Earlier studies had reported that elderly people in South Africa have more NCD risk factors than younger people [24, 25] while other studies found that self-reported NCD multi morbidity was more common among women, at older ages, those having no or low levels of education, being separated, divorced or widowed, having higher household incomes, and among those from urban areas [26].
In a recent study, [27]) posits that physical inactivity is a key risk factor of non-communicable diseases. [28] maintain that recreational football specifically decreases blood pressure and beneficial to NCDs related to cardiovascular and bone health, body composition, type 2 diabetes, and prostate cancer. According to [29], large family size and early-life farm exposure could be predisposing factors for asthma and rhinitis and respiratory symptoms among pre-school children in China. In addition, [30, 31] agree that smoking is a key risk factor for the development of asthma as avoiding tobacco smoke exposure during pregnancy might prevent or delay the development of asthma while [32] note that the prevalence of diabetes widely varied across provinces in Ecuador where higher rates were seen in provinces along the coastal region of the country.
Furthermore, [33] found higher prevalence of diabetes in coastal (8.2%) than in highlands (4.5%; p = 0.03), and jungle (3.5%; p < 0.02) regions of Peru. Thus, the need to take into account the contextual differences in studying the causes of increased NCD has been suggested [23]. In this context, non-communicable disease burden have been shown to vary across different regions, city of residence and age groups [25, 5]. [22] stressed that ageing, race, urban residence, and region matters in NCDs prevalence. Most importantly, and central to this study is the fact that earlier studies have shown that inequalities in demographic and socioeconomic status results into significant marked geographical/spatial inequities in health outcomes such as NCDs [34–37, 23, 22].
However, there remains a dearth of nationally representative analysis of the prevalence and contextual correlates of NCDs among inter-provincial migrants and non-migrants in South Africa. Therefore, the aim of the proposed study is to elucidate the prevalence and contextual correlates of NCDs among inter-provincial migrants and non-migrants in South Africa. The specific objectives among migrants and non-migrants are to; highlight the prevalence of non-communicable diseases (NCDs); and appraise the community, behavioral and individual risk factors of NCDs.