Non-communicable disease mortality trends in South Africa reveals - - PDF document

Non-communicable disease mortality trends in South Africa reveals different stages of epidemiological transition

B Nojilana MPH, Pillay-van Wyk PhD, J D Joubert PhD, RA Roomaney MPH, D Bradshaw DPhil Introduction Accounting for relatively low proportions of the total deaths in low income countries, a high proportion

• f the global non-communicable disease (NCD) burden, none-the-less, occurs in these settings, making

the prevention of these conditions an important consideration for improving global health (Beaglehole et al, 2011, WHO, 2013). Mortality estimates from the 2nd South African National Burden of Disease (SA NBD) Study highlights rapid changing mortality trends in the past 16 years, largely due to the impact of the HIV/AIDS pandemic (Pillay van Wyk et al, 2016). However, they reveal a considerable burden of non-communicable diseases which accounted for 43.4% of all deaths in 2012, higher than the 33.6% of deaths from HIV/AIDS and TB combined. South Africa is an upper middle-income country with a variety of living conditions spanning wealthy and middle-income suburbs, deprived peri-urban areas, rural farms and under-developed rural areas. It has a diverse population, currently totalling approximately 56 million people. Historically, people of Khoi, San, Bantu, European and Indian descent pioneered the country and have been joined by immigrants from most continents (Steyn et al, 2005). According to the 2011 Census, 79% were black African, 9% were coloured, 3% were Indian /Asian and 9% were white1 (Stats SA, 2017). Males constituted 49% of the population (Ibid). The introduction of a non-racial democracy has marked the start of overcoming the complex systems of neo-colonial and Apartheid repression and oppression that had been endured by the South African population. However, racial classification remains an important influence on the life course in South Africa with population group wealth inequalities remaining. Poverty and inequalities are dominant socio-economic features in South African society: a detailed analysis of poverty in the country highlights the decline in poverty from 66.6% in 2006 to 53.2% in

• 2011. A reversal has been observed with the poverty headcount increasing to 55.5% in 2015. According

to the Stats SA report on poverty between 2006 and 2015 (Stasts SA 2017), black Africans experienced higher proportions of people living below the poverty line (47%) compared to 23% coloured, 1% of Indians and less than 0.5% of white South Africans. The Gini coefficient has declined from 0.72 in 2006 to 0.68 in 2015. From the same report, the estimated percentage of persons vulnerable to hunger has declined from almost 30% in 2002 to 13% in 2016. Urbanisation and migration are also strong demographic features of the South African population, particularly in the post-Apartheid era and following the abolishment of “influx control” legislation that prevented black African population from settling in urban areas. Currently, 62% of the population live in urban areas. Based on indicators such as the Human Development Index, the African continent stands out as being somewhat lower than the global average in terms of health, education and living standards (Adogu et al, 2015). None-the-less, African countries are undergoing varying degrees of human development, and this is accompanied by demographic and epidemiological transition (Omran AR 1971, Mensah &, Mayosi 2011). This transition from infectious diseases to NCDs is posing a major challenge to the health of those affected, but also places an enormous burden on the already stretched and under- resourced health systems (Levitt et al, 2011, Boutayeb A, 2006).

1 The population group classification is based on self-reporting according to the groups defined by the Population

Registration Act of 1950, i.e. black African, coloureds (persons of mixed descent), Indian/Asian (persons of Indian descents), white (persons of European descent). This classification is being used to highlight issues that reflect effects of historical disparities, and the authors do not subscribe to this classification for another purpose.

This study aims to explore the differences in population group mortality trends for specific causes and disease categories of NCDs for South Africa for the period 2000 - 2012 from the 2nd SA NBD Study with a view to informing interventions to reduce the burden and identify trends that might be experienced in other countries in the region as they undergo health transitions. Method The 2nd SA NBD Study used vital registration cause-of-death data from Statistics SA for the period 1997-2012. Detailed analysis of population group was done from 2000 onwards due to the large proportion labelled unknown from 1997-1999. Data integrity was assessed using data cleaning processes and validity checks. Causes of death with multiple underlying causes, were recoded to address identified inconsistencies based on epidemiological and clinical expertise within the team. Adjustments for under-registration of deaths were made using demographic methods. The number of cause-specific non-natural deaths were derived using data from a national survey of mortuaries and a national injury mortality surveillance system. Misclassified HIV/AIDS deaths were identified using a regression approach and these deaths were reallocated to HIV/AIDS. Causes that were not regarded as valid underlying causes of death were redistributed by age, sex and population group. More detail about the cleaning and recoding of the data can be found in the technical report on the cleaning and validation of the data (Pillay van-Wyk, 2014). Causes of death were grouped according to the SA NBD List. This list comprises of 140 single causes

• f death, 24 disease categories and four broad cause groups. Age-standardised death rates (ASDRs)

were calculated using mid-year population estimates (Dorrington, 2013) and the WHO world standard (Ahmed et al, 2001). Population group information was available from 2000 onwards, categorised according to apartheid defined (racial) population groups (see footnote) Results While 43% of all deaths in South Africa in 2012 were due to NCDs, Figure 1 shows a large difference in the proportions of deaths due to NCDs by population group. The proportion for whites and Asians was close to 80% over the whole period, the proportion of deaths among coloureds that were due to NCDs was about 60% and the proportion among Africans was below 40%. This proportion decreased from 1997 to 2005 and then increased, largely reflecting the substantial impact of the HIV/AIDS pandemic and the effect of treatment roll-out. Figure 1: Trends in NCD deaths as a proportion of total deaths by population group, SA NBD 2012

10 20 30 40 50 60 70 80 90 100 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Percentage deaths (%) Years

Africans Whites Asians Coloureds

Cardiovascular disease was the major cause of death from NCDs and accounted for 43% of deaths in

• 2012. The proportion of death by disease category varied by population groups (Fig 1). Cardiovascular

disease ranged from 49% for Asians to 38% for coloureds. Mortality from cancer accounted for higher proportions in whites (29%) and coloureds (27%) while it accounted for 19% in Asians and 16% in black Africans. Black Africans had higher mortality from diabetes (10%) while respiratory disease deaths were higher among coloureds (12%) compared to the remaining population groups. Figure 2: Non-communicable disease mortality by disease categories per population group, SA NBD 2012 Figure 3 shows the trends in specific causes of NCDs by population group. Asians have a uniquely high level of ischaemic heart disease (IHD) mortality, which, although declining since 2006, remains high with a rate that is nearly twice as high as that of whites and coloureds. IHD was lowest in black Africans. The mortality rate from cancers was highest in coloureds, followed by whites, and then Asians, with black Africans reporting the lowest rates. Black Africans had the highest mortality rates for cerebrovascular disease (stroke) since 2003 compared to the other population groups. There has, however, been a decline in mortality from stroke in all population.

Figure 3: Trends in selected non-communicable disease age-standardised death rates by population group, SA NBD 2000 - 2012

groups with the biggest decline among Asians and coloureds. Hypertensive heart disease (HHD) showed a little change over the period for whites, who also had the lowest mortality rates. Black Africans had the highest HHD mortality rate followed by coloureds and Asians. The mortality rate from diabetes increased for black Africans and decreased for Asians over the study period. Asians had higher rates for renal disease followed by black Africans, then coloureds and whites. The overall mortality rates from cancer can be attributed to high lung and prostate cancers for males and breast and cervical cancer for females (Nojilana et al, 2016). Discussion Our study has revealed that the epidemiological transition is occurring at different paces among population groups in South Africa. NCD death rates have decreased since 2003, and profiles and trends by population group and causes differ. The Asian profile is unique as it is characterised by extremely high rates of IHD, stroke, diabetes and renal disease at the beginning of the study period. With the exception of renal disease, the rates for this group declined considerably over the study period. However, this population group continues to have the highest rates of IHD and renal disease when compared to other groups. The rates for other non-communicable diseases are more typical and have also tended to decline. In general, whites experienced the lowest mortality rates from cause-specific non-communicable diseases. This group had considerably lower rates from stroke, HHD, diabetes and renal disease throughout the period. Compared with other population groups, rates for IHD, cancers and chronic obstructive pulmonary disease (COPD) were higher for whites and with the exception of IHD and COPD, which declined slightly, there has been little change in mortality for the whites during this period. The pattern for whites and Asians is in keeping with stage 4 of the cardiovascular transition described by Pearson et al (1993), the pattern for black Africans is more consistent with stage 2. Mortality rates from stroke and HHD were highest for black Africans and showed little change over the study period. In contrast, mortality rates from IHD and cancers were lowest for black Africans. Voster (2002) suggested that stroke is a unique feature of health transition associated with urbanisation in black

• Africans. Additionally, her study suggested that black Africans may be protected against IHD because
• f the favourable lipid profiles. Mortality from diabetes and renal disease increased for black Africans

considerably over the study period, indicating a shift in this population group towards stage 3 of the cardiovascular transition. Coloureds experienced typical levels of mortality for most of the cause-specific NCDs but had somewhat higher death rates for cancers and COPD. This pattern might be associated with the high use

• f tobacco products by both males and females in this group (Sitas et al, 2013).

Health disparities result from social, educational or environmental deprivation (Rothberg, 2008), as well as disparities in health care (Feller et al, 2010). In addition, genetic and cultural factors play a role as described by Micklesfield et al (2012) in terms of the occurrence of obesity. Mortality from circulatory diseases is known to vary between ethnic groups. In particular, a considerable excess of ischaemic heart disease among people of Indian descent has been reported from several countries across the world. Another consistent finding reported from Britain and elsewhere is the high incidence of hypertension among people of African descent (Anald et al, 2000). Our data have important public-health and clinical implications for the prevention and treatment of non- communicable diseases in South Africa. The government has introduced the Strategic Plan for The Prevention and Control of Noncommunicable Disease 2013-2017, influenced by the 4-by-4 strategy promoted by WHO. There is clearly a need to strengthen those strategies and policies already in place to reduce the burden of NCDs. For example, South Africa is one of a few of the developing countries that have implemented comprehensive tobacco control policies to address the growing epidemic of tobacco use, regulations to control the use of trans-fats in processed food, and a salt reduction policy to address hypertension. Such policies have been shown to be successful in developed countries (Vartiainen et al, 2010; OECD, 2010).

The effect of different stages of epidemiological transition is especially evident in South Africa, a country of great diversity that extends from highly industrialised cities with an urban advanced- economy lifestyle to remote rural regions with more traditional lifestyles. Improvements in socioeconomic status when migrating from rural to urban settings may also be associated with shifts in diets that predispose the development of atherosclerosis through the uptake of fast food and foods high in sugar and fat (Peer et al, 2014). This diversity is reflected in the mortality profiles of different population groups, with black South Africans experiencing a much higher burden of poverty-related diseases and injuries linked to continued impoverishment effected under apartheid legislation (Coovadia et al, 2009). The differing mortality trends in the different population groups highlight the need to assess risk factors to assist in evaluating the impact of implemented policies and strategies in the country, particularly as they impact on different sectors of society. In addition, there is a need to further explore the trends to understand the inevitability of the cardiovascular transition as societies undergo development. Mensah and Mayosi (2013) have argued that the health transition in Sub-Saharan Africa is characterised by the simultaneous occurrence of epidemic infectious diseases and a rise in NCDs. They conclude that there is a need for Africa to add the fifth risk factor (transmissible agents) and a fifth condition (neuropsychiatric illness) to the 4-by-4 agenda for the prevention and control of NCDs. They consider that a 5-by-5 strategy that recognises 5 risk factors (tobacco smoking, unhealthy diet, physical inactivity, excessive alcohol use and transmissible agents) and 5 diseases (cardiovascular disease, chronic lung disease, diabetes, cancer and neuropsychiatric illness) is required to combat NCDs in sub- Saharan Africa. Our study reflects the importance of monitoring the burden of disease so as to discern progress and identify priorities.

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