Predictive factors for repetition of the tuberculin test after a nonreactive test in patients with HIV/AIDS

objective: the outcome of interest was repetition of the tuberculin skin test (tst) and the objectives were to estimate the rate of tst repetition, the probability of no tst repetition after 1 year, and the probability of no tst repetition at the end of the follow-up period in patients whose initial test was nonreactive. the study also set out to analyze factors associated with the time until tst repetition at two hiv/aids referral services that carry out the tst on a routine basis in recife, pernambuco, brazil. methods: a cohort of hiv-positive patients who initially tested nonreactive on the tst were followed from november 2007 to february 2010. the kaplan-meier method was used to estimate the probability of not repeating the tst, and cox's regression analysis was used to analyze the factors associated with time until repeating the tst. cox's multivariate analysis was stratified according to each hospital where patients were followed, because this variable did not respect the principle of proportionality of risk. results: the probability of not repeating the tst for 1 year was 80.0% and at the end of the follow-up period it was 42.0%. the variables that remained associated with tst repetition in the final cox multivariate model were an age of 40 years or older, body mass index between 18.0 and 24.9, being female, and years of schooling. conclusions: this study encountered a very low tst repetition rate after 1 year of follow-up and identified groups of individuals who should be the target of interventions aimed at repeating the tst.