The association of demographics and occupational factors with latent tuberculosis infection in radiology staff at public sector hospitals in the eThekwini health district
Introduction Tuberculosis remains a leading cause of death, second to the Human Immunodeficiency Virus. The risk of latent tuberculosis infection and active tuberculosis disease is a known occupational hazard. In South Africa, a high tuberculosis burden country, the potential of Mycobacterium tuberculosis transmission to health care workers is high. This includes diagnostic radiographers and other radiology staff working in radiology departments. Purpose of the Study This study aimed to investigate the association of demographic and occupational factors with latent tuberculosis infection in radiology staff in public sector hospitals of the eThekwini Health District. Methodology This cross-sectional study was conducted from 26 February 2013 to 07 June 2013. Quantitative methods were used to test for associations of demographic and occupational factors with latent tuberculosis infection in participants. A sample size of 181 participants for an estimated population of 340 radiology staff was recommended at the proposal stage. The study consisted of two phases; the questionnaire survey (phase one) and the administration of a two-step tuberculin skin test (phase two). Data was obtained with regard to demographics, occupational history, social behaviours, medical history; and family and home histories. Demographic and occupational associations with latent tuberculosis infection were made in relation to the size of the first tuberculin skin test induration. Frequency distributions were developed to describe data categories. Pearson’s and Spearman rho’ correlation coefficients were used to test for correlations between the independent variables. The chi-square test was used to determine associations between the categorical independent variables and the dependent variable. Bivariate analyses were performed using these tests. The multivariate analysis was performed using logistic and linear regression on the dependent variable. Results A total of 182 questionnaires were returned from approximately 280 radiology staff. At the outset, all doctors working in the radiology department had to be excluded due to numerous failed attempts to enlist their participation. Fifty-three (29.12 percent) participants were excluded from phase one of the study and a further thirteen participants were excluded from phase two. The total sample was 116 participants. Of the 116 participants, 86.2 percent tested positive for latent tuberculosis infection at the first step of the two-step testing method used. One (0.86 percent) participant went on to convert at the second step, testing positive at this level. Demographic associations with latent tuberculosis infection included age (older) as an associated factor. A significant demographic association with latent tuberculosis infection was the use of alcohol (p-value 0.033 on the multivariate analysis). Occupational associations with latent tuberculosis infection included longer durations of employment. The annual income (higher income earners) displayed significant associations with latent tuberculosis infection (p-value 0.048 on the multivariate analysis). It is necessary in this study to note that participants include support personnel (lower income earners) making up 37.8 percent of the study, diagnostic radiographers making up 48.3 percent; and radiography managers/assistant managers (highest income earners) making up 13.8 percent of the study. Conclusion and recommendations The risk of transmission of Mycobacterium Tuberculosis to health care workers is a known occupational hazard. This study has described the prevalence of latent tuberculosis infection in radiology staff, at district and regional hospitals within the eThekwini Health District. With 23.62 percent of all participants already having active TB disease and 86.2 percent of the tested group displaying positive results for latent tuberculosis infection, using the tuberculin skin tests, the need for tuberculosis screening is essential. The findings of this study will be used as a health improvement mechanism for stakeholders, having identified potential gaps in medical screening in healthcare in Kwa-Zulu Natal. This study makes recommendations for the early detection of active tuberculosis infection and the monitoring of health care workers that are latently infected, thus assisting in reducing the rate of conversion of latent tuberculosis infection to active tuberculosis disease in radiology staff. This reduces long-term exorbitant costs related to health care associated infections, such as tuberculosis. It also reduces rates of transmission and cross infection to both co-workers and already immunocompromised patients, helping to curb the overall epidemic in South Africa.