What are we dying from?
- Wits University
Cardiovascular diseases now account for a third of deaths in adults over 40 in a rural South African population.
A study following more than 5,000 middle-aged and older adults in rural Mpumalanga found that cardiovascular diseases now lead as the cause of death. Published in Age and Ageing, the research drew on data from Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community (HAALSI).
This study provides valuable insight into the mortality burden in a rural South African setting. Over seven years of follow-up, 1,116 participants (22.1% of the cohort) died, with cardiovascular diseases accounting for about one in three of those deaths.
Cardiovascular diseases affect the heart and blood vessels. In this study, they included acute cardiac disease, stroke, and other cardiac conditions for which a more specific diagnosis could not be established.
Men died at a considerably higher rate than women – about 57% higher over the follow-up period. The risk of death also increased steadily with age.
But infections remain a major part of the mortality burden.
Sepsis, acute respiratory infections, pneumonia, and diarrhoeal diseases still accounted for 23.8% of deaths. Cancers accounted for 14.4%, while HIV/AIDS and TB accounted for a further 10.1%.
“The figures do not describe a clean handover from infectious to non-communicable diseases. HIV and TB have receded from their epidemic peak, but infections together still accounted for almost 34% of deaths in the cohort,” says Dr Chodziwadziwa ‘Cho’ Kabudula, lead study author and Assistant Director for Data and Analytics at the SAMRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt). The HAALSI study is nested within Agincourt’s broader longitudinal research platform.
From the HIV epidemic to an ageing population
The findings form the latest chapter in a much longer mortality story.
At the height of the HIV epidemic between 2004 and 2007, earlier Agincourt research found that HIV/AIDS and TB accounted for 40% of deaths among men and 50% among women. Life expectancy fell sharply.
The expansion of antiretroviral therapy changed the curve. By 2018, overall mortality in Agincourt had returned to levels last seen before the HIV epidemic. More people with HIV were surviving into middle and older ages.
But the return of life expectancy did not mean a return to the same disease pattern. As the population grew older, cardiovascular diseases and other chronic conditions became more prominent, while HIV, TB and other infections continued to claim lives.
“The result is a health system facing several burdens at once, rather than moving neatly from one dominant disease burden to another,” says Kabudula.
What everyday functioning can reveal
The study went beyond recording causes of death, and linked mortality to health, social and physical-function measures which were collected when participants entered the cohort.
Some of the strongest warning signs were visible in ordinary daily life.
Participants were asked whether they had difficulty walking across a room, dressing, bathing, eating, getting into or out of bed, or using the toilet. Those reporting difficulty with four or more of these activities had approximately four times the risk of dying compared with people reporting no limitations.
Walking speed and grip strength also mattered. Participants with the strongest grip had about half the mortality risk of those with the weakest grip, while slower walking was associated with a greater risk of death.
Poor self-rated health was another strong predictor. People who described their health as “very bad” had almost four times the risk of death of those who described it as “very good”.
Underweight participants had an 87% higher risk of death than those in the normal weight range. Smoking, severe blood-pressure abnormalities, diabetes, previous stroke, and a history of TB were also associated with increased mortality.
The unfinished work of HIV care
People living with HIV who were taking antiretroviral treatment and had an unsuppressed viral load had approximately twice the mortality risk of HIV-negative participants. By contrast, the researchers observed lower cardiovascular mortality among people whose HIV was virally suppressed than among HIV-negative participants. Researchers caution that this should not be interpreted as HIV having a protective effect. One possible explanation is that people receiving regular HIV care have more frequent contact with the health system and, therefore, more opportunities for blood-pressure screening, treatment, and other preventive care.
“South Africa has built extensive systems for long-term HIV treatment, monitoring and adherence support. Those systems could provide a foundation for detecting and managing hypertension, diabetes and other chronic conditions, rather than treating HIV and non-communicable diseases through separate services,” says Professor Kathleen Kahn, Principal Scientist at Agincourt.
People are living longer because of one of South Africa’s most important public health achievements. Many are now reaching older ages with cardiovascular diseases, diabetes, disability or several conditions at once. Others remain vulnerable to HIV, TB and acute infections.
“Agincourt’s mortality record shows why the health system must manage several concerns at the same time,” says Kahn.