Climate change and cardiovascular diseases in India and South Africa: impacts, perceptions and policy responses

Background
As a result of anthropogenic climate change, global average temperatures, the severity, frequency and intensity of extreme weather events are on the rise. Several diseases,
including vector borne diseases, mental health, conflicts and non-communicable diseases, such as cardiovascular diseases (CVDs), are climate-sensitive and climate change is
contributing to driving their disease burden.
Primarily a lifestyle disease, CVDs are already the leading cause of mortality worldwide, with environmental factors such as temperature and air pollution further contributing to their burden. The impacts of climate change are highly regional and depend on contextual vulnerabilities. This especially poses a major public health challenge in low- and middle-income (LMIC) countries, which have limited resources availability and capacity to react to the threat.
Despite a growing body of evidence on the association between climate change variables, such as temperature, and CVDs, there remains a large knowledge and evidence gap on this topic in LMICs, including India and South Africa, which have been examined in this body of work. The findings contribute to furthering our understanding of how climate change affects CVDs in India and South Africa.
Methods
A multi-methods approach was used, comprising of quantitative and qualitative approaches. The association between apparent temperature (Tapp) and in-hospital CVD mortalities was modelled using a case crossover approach with a distributed lag non-linear model (dlnm) in
Puducherry, India. A similar approach using a negative binomial distribution with the dlnm was used to model the association between Tapp and CVD morbidity, measured through CVD hospitalizations, in the Limpopo Province of South Africa. Both models considered a 21-day lag period.
Key informant interviews were carried out in Puducherry with medical professionals, environmentalists and government officials to understand their perspectives on climate
change and health, with a focus on CVDs. In light of the paucity of research on climate change and health in India, these interviews were also used to understand the research
barriers and challenges for climate change and health research in Puducherry. The findings were analysed using qualitative thematic analysis following the Framework method.
National and State level policies and document pertaining to climate change, adaptation, health, environment and CVDs were systematically reviewed. The policies were analysed
qualitatively using the Framework method and content analysis to understand how CVDs are represented in the climate change adaptation policy space in India and the gaps therein.
Findings
The optimal Tapp range for Puducherry is between 30 to 36°C, with temperatures above and below this associated with an increased risk of CVD mortality. Up to 17% of in-hospital
mortalities were attributable to non-optimal Tapp in Puducherry between 2011 and 2020. Out of this 9.1% and 8.3% of the burden was attributable to heat and cold respectively, with males being more vulnerable to cold and females over 60 years of age affected predominantly by heat. Patients were more prone to cerebrovascular accidents during hot periods. In Limpopo, the optimal Tapp range is between 25 to 27°C, and 8.5% of CVD hospital admissions were attributable to heat and 1.1% to cold.
In Puducherry, the perceived health risks from climate change were largely a product of individual knowledge of the local public health burden and vulnerabilities, with some level of scepticism on the association between climate change and CVDs. There was a perceived gap in technical education about climate change and health, despite awareness of the same as a concept. Informants also expressed a need for multi-level, inclusive awareness programs targeting different social groups. Data collection systems, access to health data and underdeveloped technical and methodological research capacity were considered the biggest research barriers when it came to climate change and health. The topic was not considered a research or political priority, with limited resources being allocated to most climate sensitive outcomes. Informants also described a tendency for environmental health research to centre on conventional health outcomes, as opposed to CVDs.
Most Indian national and State policies are focused on vector borne diseases and heat-related illnesses, the latter of which does not fully encompass all temperature sensitive
CVDs, as part of the efforts to address climate change impacts on health. Strengthening health surveillance systems to capture CVDs could also contribute to improving research
output on the topic from India and strengthen contextual adaptation planning. The political commitment to addressing the health impacts of climate change as well as CVD management could be used in tandem to facilitate interventions and actions on climate change and CVDs. Many of the State level plans were found to be incomplete or simply templates, and thus there is an urgent need to focus on ensuring the development or completion of these plans.
Conclusion
Climate change impacts on CVDs are an emerging problem of concern for both India and South Africa. Non-optimal temperatures are associated with increasing the risk of CVD
events in both countries. Parallel streams focusing on improving awareness and education and improving monitoring and surveillance systems could potentially contribute to
addressing this issue in India. There is a pressing need to improve evidence synthesis on the topic in both countries, with efforts taken to ensure climate change and health becomes a priority for both research and policy supported interventions and actions for adaptation.