Incidence of tuberculosis and the need of prophylactic treatment in persons living with HIV in Stockholm during the era of anti-retroviral therapy 1996-2013.

BACKGROUND: The aim of this observational cohort study was to determine the incidence and risk factors of active tuberculosis (TB) in persons living with HIV in a low endemic setting over a 17-year time period when combination antiretroviral therapy (ART) has been available. We thereby aimed to understand the usefulness of TB chemoprophylaxis among HIV patients with latent TB.

METHODS: All 2127 adult patients diagnosed with HIV January 1996-December 2013 at the Karolinska University Hospital in Stockholm County were eligible. After exclusion of 259 patients transferred to other clinics, 1868 were followed until TB diagnosis, death or end of study period (December 2013). The median follow-up time was 7.9 years (interquartile range, 3.9-11.5).

RESULTS: Active TB was diagnosed in 92 patients, corresponding to an incidence rate of 6.2 cases (95% CI 5.1-7.6) per 1000 person-years with a significant decline over time. The majority (52%) of TB cases were diagnosed within 1 month from HIV diagnosis. Being a migrant from a TB-endemic region, was the only patient characteristic associated with significantly higher risk of active TB (Hazard Ration, HR: 8.54, 95% confidence interval, CI: 3.09-23.61 in a multivariate regression analysis controlling for route of HIV transmission, year of HIV diagnosis and CD4-cell count and viral load at HIV diagnosis. The number needed to treat to prevent one case of TB among patients in this high-risk group was 22 (95% CI 26-47).

CONCLUSION: The incidence of active TB in persons living with HIV in Stockholm County declined significantly after the introduction of ART but was still 80 times higher than in the general population at the end of the study period. The therapeutic gain of chemoprophylaxis in low endemic settings should be weighed against costs and side effects.