An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners

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dc.contributor.advisorAdams, Shahieda
dc.contributor.advisorEhrlich, Rodney
dc.contributor.authorWilliams-Mohamed, Yumna
dc.date.accessioned2026-06-30T08:49:59Z
dc.date.available2026-06-30T08:49:59Z
dc.date.issued2026
dc.date.updated2026-06-30T08:48:42Z
dc.description.abstractBackground: There is a well-established causal link between occupational asbestos exposure and lung diseases such as pneumoconiosis and mesothelioma. Higher mortality rates in former asbestos miners compared to the general population are thus anticipated. However, no local, large-scale studies have been conducted to evaluate the all-cause mortality experience in this subpopulation. We investigated all-cause mortality among a cohort of former South African asbestos miners captured on the Asbestos and Kgalagadi Relief Trusts' Inyosi database. Methods: All-cause standard mortality ratios (SMRs) and crude mortality rates (CMRs) were calculated for 11 343 ex-miners. Mortality predictors were modelled using Cox regression analysis and mortality trends were assessed by examining annual all-cause CMRs and SMRs over the 20-year study period. Results: The cohort's all-cause mortality exceeded that of the general population by 4% (SMR=1.04; 95% CI: 1.01-1.07). Radiological abnormalities based on ILO profusion category were strong predictors of mortality with adjusted hazard ratios (aHRs) ranging from 1.13 (95% CI: 1.05-1.23) to 2.34 (95% CI: 1.52-3.58). Other significant predictors were a BMI less than 18.5 kg/m2 (aHR=1.46; 95% CI: 1.35-1.58), history of previous smoking (aHR=1.43; 95% CI: 1.35-1.53), costophrenic angle obliteration (aHR=1.27; 95% CI: 1.14-1.41), and reduced forced expiratory volume in one second and forced vital capacity (aHR=1.60; 95% CI:1.41-1.81 and aHR=1.26: 95% CI: 1.12-1.42, respectively, for z-scores less than -3.0). The SMR decreased with time. Conclusion: Interpretation of mortality in this cohort was limited by incomplete data, preventing firm conclusions. However, radiologic and spirometric measures emerged as significant predictors of mortality, potentially enabling risk stratification and guiding targeted interventions. Such interventions include early management of respiratory complications and smoking cessation, which could mitigate mortality risk.
dc.identifier.apacitationWilliams-Mohamed, Y. (2026). <i>An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners</i>. (). University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine. Retrieved from http://hdl.handle.net/11427/43416en_ZA
dc.identifier.chicagocitationWilliams-Mohamed, Yumna. <i>"An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners."</i> ., University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine, 2026. http://hdl.handle.net/11427/43416en_ZA
dc.identifier.citationWilliams-Mohamed, Y. 2026. An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners. . University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine. http://hdl.handle.net/11427/43416en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Williams-Mohamed, Yumna AB - Background: There is a well-established causal link between occupational asbestos exposure and lung diseases such as pneumoconiosis and mesothelioma. Higher mortality rates in former asbestos miners compared to the general population are thus anticipated. However, no local, large-scale studies have been conducted to evaluate the all-cause mortality experience in this subpopulation. We investigated all-cause mortality among a cohort of former South African asbestos miners captured on the Asbestos and Kgalagadi Relief Trusts' Inyosi database. Methods: All-cause standard mortality ratios (SMRs) and crude mortality rates (CMRs) were calculated for 11 343 ex-miners. Mortality predictors were modelled using Cox regression analysis and mortality trends were assessed by examining annual all-cause CMRs and SMRs over the 20-year study period. Results: The cohort's all-cause mortality exceeded that of the general population by 4% (SMR=1.04; 95% CI: 1.01-1.07). Radiological abnormalities based on ILO profusion category were strong predictors of mortality with adjusted hazard ratios (aHRs) ranging from 1.13 (95% CI: 1.05-1.23) to 2.34 (95% CI: 1.52-3.58). Other significant predictors were a BMI less than 18.5 kg/m2 (aHR=1.46; 95% CI: 1.35-1.58), history of previous smoking (aHR=1.43; 95% CI: 1.35-1.53), costophrenic angle obliteration (aHR=1.27; 95% CI: 1.14-1.41), and reduced forced expiratory volume in one second and forced vital capacity (aHR=1.60; 95% CI:1.41-1.81 and aHR=1.26: 95% CI: 1.12-1.42, respectively, for z-scores less than -3.0). The SMR decreased with time. Conclusion: Interpretation of mortality in this cohort was limited by incomplete data, preventing firm conclusions. However, radiologic and spirometric measures emerged as significant predictors of mortality, potentially enabling risk stratification and guiding targeted interventions. Such interventions include early management of respiratory complications and smoking cessation, which could mitigate mortality risk. DA - 2026 DB - OpenUCT DP - University of Cape Town KW - asbestos-related disease, mortality rates, asbestos miners, predictors, risk factors, determinants LK - https://open.uct.ac.za PB - University of Cape Town PY - 2026 T1 - An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners TI - An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners UR - http://hdl.handle.net/11427/43416 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/43416
dc.identifier.vancouvercitationWilliams-Mohamed Y. An evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners. []. University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine, 2026 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/43416en_ZA
dc.language.isoen
dc.language.rfc3066eng
dc.publisher.departmentDepartment of Public Health and Family Medicine
dc.publisher.facultyFaculty of Health Sciences
dc.publisher.institutionUniversity of Cape Town
dc.subjectasbestos-related disease, mortality rates, asbestos miners, predictors, risk factors, determinants
dc.titleAn evaluation of mortality rates and their determinants in a South African cohort of former asbestos miners
dc.typeThesis / Dissertation
dc.type.qualificationlevelMasters
dc.type.qualificationlevelMMed
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