CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 5, September/October 2022 260 AFRICA Out-of-hospital cardiac arrests in the city of Cape Town metropole of the Western Cape province of South Africa: a spatio-temporal analysis Willem Stassen, Elzarie Theron, Thomas Slingsby, Craig Wylie Abstract Background: The incidence of out-of-hospital cardiac arrest (OHCA) is expected to increase in sub-Saharan Africa along with the incidence of cardiovascular disease. In low-resource settings (LRS), OHCA carries a negligible survival rate. Interventions to improve OHCA survival might not be cost effective for many LRS, and therefore need to be targeted to areas of high incidence. The aim of this study was to describe the temporal and geographic distribution of OHCA in the City of Cape Town, South Africa, and their proximity to percutaneous coronary intervention (PCI) resources. Methods: In this retrospective study, OHCA data between 1 January and 31 December 2018 were extracted from public and one private emergency medical services in the Western Cape. For temporal analysis, distribution of OHCA according to time of day, day of the week and month of the year were subjected to chi-squared testing. For geospatial analysis, cluster and outlier, and hotspot analyses were performed. Proximity analysis was employed to determine the driving time from OHCA location to the closest PCI-capable facility. Results: A total of 929 patients with OHCA received an emergency medical services response in the City of Cape Town, corresponding to an annual prevalence of 23.2 per 100 000 persons. The distribution of OHCA incidence was not explained by month of the year (p = 0.08) or day of the week (p = 0.67). A statistically significant variation in OHCA incidence was explained by time of day (p < 0.01) with 30% (n = 279) of all OHCAs occurring from 05:00 to 09:59. Geospatial analysis yielded a large area of hotspots (99% confidence interval) over the centre of the metropole, Cape Flats and southern suburbs. The median (interquartile range) driving time from the incident to the closest PCI-capable facility was 10:22 (08:05) minutes. Conclusion: Incidents of OHCA occurred predominantly at home during the mid-morning, with hotspots around the city centre and residential suburbs of Cape Town. While the incidents occurred close to PCI-capable facilities, some areas remained underserved and access to PCI for OHCA victims may be impossible due to socio-economic factors. With an increase in OHCA incidence expected, it is essential that contextual, cost-effective management interventions be developed and implemented. Keywords: out-of-hospital cardiac arrest, resuscitation, emergency medical care Submitted 12/11/21, accepted 1/4/22 Published online 8/6/22 Cardiovasc J Afr 2022; 33: 260–266 www.cvja.co.za DOI: 10.5830/CVJA-2022-019 Out-of-hospital cardiac arrest (OHCA) is defined as the cessation of cardiac mechanical activity that occurs outside the hospital setting and is confirmed by the absence of signs of cardiovascular circulation. The incidence of OHCA ranges from 28.3 per 100 000 person-years in Asia to 54.6 per 100 000 personyears in North America.1 There is a paucity of literature on the incidence of OHCA in low-resource settings, especially Africa.2,3 One study from South Africa reported an incidence of 6.4 per 100 000 population. However, this is likely under-estimated as the data were limited to cases seen by emergency medical care students in the Johannesburg area.4 Despite the lack of epidemiological data, it is clear that the incidence of cardiovascular diseases, such as ischaemic heart disease, is on the increase in sub-Saharan Africa (including South Africa); a doubling in the incidence is expected between 1990 and 2030.5-7 When considering that studies from the United States note that cardiovascular disease is the cause of sudden cardiac arrest in up to 80% of cases,8 it is likely that the incidence of OHCA in South Africa is not only under-estimated but also rising. OHCA carries a high mortality rate.3,4,9-13 A 2020 scoping review on OHCA in low-resource settings reported return of spontaneous circulation (ROSC) rates, ranging from zero to 62%, survival to discharge rates of between one and 16.7%, and rates of favourable neurological outcome of between one and 9.3%.1 The only African study included in this scoping review was from South Africa and reported a survival to hospital arrival rate of 18% in a Johannesburg-based cohort.4 No African studies reported on longer-term survival. Despite a high mortality rate, some interventions have been found to increase survival rate in OHCA, most notably, bystander cardiopulmonary resuscitation (CPR)14-16 and early Division of Emergency Medicine, University of Cape Town, Cape Town, South Africa Willem Stassen, BTEMC, MPhil EM, PGDip Applied Ethics, PhD, willem.stassen@uct.ac.za Elzarie Theron, BA, BA Hons (Psychology), MA (Research Psychology) Craig Wylie, BTEMC, MPhil EM Geographic Information Systems Support, Digital Library Services, University of Cape Town, Cape Town, South Africa Thomas Slingsby, MSc Geomatics Division of Emergency Medicine, Stellenbosch University, Stellenbosch, South Africa Craig Wylie, BTEMC, MPhil EM
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