1. King’s College Hospital, London, UK;, Division of Pulmonology, Department of Medicine, Stellenbosch University & Tygerberg Hospital, Cape Town,
2. Division of Pulmonology, Department of Medicine, Stellenbosch University & Tygerberg Hospital, Cape Town,
3. Division of Epidemiology and Biostatistics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa