A cross-sectional study of tuberculosis among workers in Tygerberg Academic Hospital, Western Cape province, South Africa
Thesis (MMed)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Introduction: The morbidity and mortality associated with tuberculosis (TB) disease is of grave consequences for the health and employment of afflicted individuals. Healthcare workers are identified amongst high risk groups in communities. The prevalence/incidence of TB is dependent on the presence of associated risk factors which varies in diversity and intensity in different communities and workplaces. Understanding the risk factors operating in any given environment is indispensable to any tuberculosis control programme. Objective: The objective of this study was to describe the occurrence and trends of TB disease as well as to determine the risk factors associated with the disease among Tygerberg hospital employees. Method: A cross-sectional descriptive study design with a nested case-control component was used to determine the occurrence (and trends) and risk factors of TB disease respectively. Occurrence and trends of tuberculosis: The frequencies, distribution and trends of TB disease from 2008 to 2011 were obtained by calculating and comparing the annual incidence rates for each variable. Cases were identified from the occupational health clinic TB register, while the various denominator data were obtained from the Human Resource database. Determination of risk factors: Cases were recruited from the occupational health clinic TB register and controls were randomly selected from unaffected workers during the study period. Self-administered risk factor questionnaires were completed by both cases and controls. Multivariate logistic regression analysis was used to determine the association between known and suspected risk factors and the occurrence of TB disease amongst employees. Results: Sixty six cases of TB disease occurred in the workforce during the study period resulting in an annual average incidence rate of 397/100,000 population (95% CI: 307/100,000-505/100,000). Twenty three (34.8%) of the 66 cases occurred in Housekeeping staff, making them the most affected sub-group [1181/100,000 population (95% CI: 747/100,000-1768/100,000)]. The rate of TB disease in nurses was 1.7 times (95%CI: 1.4-2.0) that of doctors. Workers in the 40-49 years age-group experienced the highest incidence [490/100,000 population (95%CI: 329.6/100,000-706.8/100,000)] of TB disease compared to the other age-groups. There was no obvious difference in gender occurrences. Disease rates varied among different racial groups, with the highest rate in black employees [1473/100,000 population, (95%CI: 924/100,000-1981/100,000)]. Distribution of TB disease in the institution was widespread, with security department being the most affected [2500/100,000 population (95%CI: 311/100,000- 9262/100,000)]. There was a downward but statistically insignificant (annual range 9-23; p=0.28) trend in the rate of disease occurrence over the study period. No previous training on TB prevention (OR: 2.97, 95% CI: 1.15 - 7.71), HIV (OR: 67.08, 95% CI: 7.54 – 596.64) and working without knowledge of TB risk profile of the workplace (OR: 8.66, 95% CI: 1.10 – 67.96) were associated with TB disease occurrence. Conclusion: Occurrence of TB disease among Tygerberg hospital employees was low compared to that of the general population of its drainage areas. Disease occurrence in the facility was wide and varied with respect to occupational groups, workplaces and time. Well-established risk factors for TB infection (and disease) were found to be determinants of disease occurrence in the facility.