Skin test screening for tuberculosis among healthcare students: a retrospective cohort study

Aim of the study was to document the baseline prevalence of healthcare students positive to tuberculosis skin tests screening.

Between 2008-2010, students admitted to healthcare courses (medicine, nursing, physiotherapy...) at Sapienza university in Rome were requested to carry out personal tuberculosis skin test screening in their local district or town healthcare centers according to the italian guidelines. At the time interferongamma release assays (IGRA) testing was not adopted for large screening. Demographic characteristics, tuberculosis screening results, healthcare course, tuberculosis vaccination status were recorded.

A cohort of 2,500 university healthcare students were screened by several Italian Hygiene Offices using tuberculin skin test and Tine test. Overall 131 (5.2%) healthcare students resulted positive to some tuberculosis skin test screening. Tuberculin skin test was carried out on 2,029 students (81.2%) and conversion was observed in 107 (5.3%), whereas Tine test was carried out on 498 students (19.9%) and positive result was observed in 24 (4.8%). The Tine test use and non optimal (<72h) recording of the forearm induration in tuberculin skin tests was related mostly to some healthcare centers in Lazio and Campania regions. Previous BCG vaccination was reported by 27 healthcare students (1.1%), and only two of them showed tuberculin skin test conversion, whereas the large majority 105 (98.1%) of Mantoux positives had not been vaccinated. In univariate analysis positive tuberculin skin test was associated to growing students age (29.2 ± 10.3 vs. 23.1 ± 6.0; p<0.01). Positive tuberculin skin test was recorded in 25 (20.3%) foreign and 82 (4.3%) italian students showing a higher risk for International students (RR 4.72; 95%CI 3.14 - 7.11; p<0.01). There was no significant correlation between the different Italian regions, the various healthcare courses or gender.

The study evaluated the baseline positive skin test rate for tuberculosis among healthcare students in their first university year, showing a higher risk for the international group and revealed some problematic screening practices which need to be improved in the future screening programs.