A cross-sectional study of tuberculosis among workers in Tygerberg Academic Hospital, Western Cape province, South Africa

[摘要] ENGLISH ABSTRACT: Introduction: The morbidity and mortality associated with tuberculosis (TB) disease is of graveconsequences for the health and employment of afflicted individuals. Healthcare workers are identifiedamongst high risk groups in communities. The prevalence/incidence of TB is dependent on the presenceof associated risk factors which varies in diversity and intensity in different communities andworkplaces. Understanding the risk factors operating in any given environment is indispensable to anytuberculosis control programme.Objective: The objective of this study was to describe the occurrence and trends of TB disease as well asto 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 todetermine 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 2008to 2011 were obtained by calculating and comparing the annual incidence rates for each variable. Caseswere identified from the occupational health clinic TB register, while the various denominator data wereobtained from the Human Resource database.Determination of risk factors: Cases were recruited from the occupational health clinic TB register andcontrols were randomly selected from unaffected workers during the study period. Self-administered riskfactor questionnaires were completed by both cases and controls. Multivariate logistic regression analysiswas used to determine the association between known and suspected risk factors and the occurrence ofTB disease amongst employees.Results: Sixty six cases of TB disease occurred in the workforce during the study period resulting in anannual average incidence rate of 397/100,000 population (95% CI: 307/100,000-505/100,000). Twentythree (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 was1.7 times (95%CI: 1.4-2.0) that of doctors. Workers in the 40-49 years age-group experienced the highestincidence [490/100,000 population (95%CI: 329.6/100,000-706.8/100,000)] of TB disease compared tothe other age-groups. There was no obvious difference in gender occurrences. Disease rates variedamong 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, withsecurity 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 TBrisk profile of the workplace (OR: 8.66, 95% CI: 1.10 – 67.96) were associated with TB diseaseoccurrence.Conclusion: Occurrence of TB disease among Tygerberg hospital employees was low compared to thatof the general population of its drainage areas. Disease occurrence in the facility was wide and variedwith 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.

[发布机构] Stellenbosch University