Patient characteristics associated with different types of prison TB: an epidemiological analysis of 921 TB cases diagnosed at an Ethiopian prison.

Background: Despite incarcerated population being at an increased risk of tuberculosis (TB) and serving as a potential source of TB transmission for the general population, prison TB remains understudied. Given its adverse impact on progress towards TB elimination, World Health Organization (WHO) has identified prison TB research as a top priority to guide TB treatment/control interventions.

Methods: We retrospectively analyzed 921 notified TB cases that were diagnosed at Kality Federal Prison, Ethiopia during 2009-2017. To assess trends of microbiologically confirmed pulmonary TB (PTB), extra-pulmonary TB (EPTB), and TB-HIV co-infection, an ecological analysis of aggregated cases was used to report trends over time. Additionally, we used multivariable log binomial regression to identify patient characteristics associated with microbiologically confirmed PTB, EPTB, and TB-HIV co-infection.

Results: Microbiologically confirmed PTB proportion increased over time. Young age was identified as an important risk factor for EPTB (adjusted prevalence ratio [aPR] = 1.74, 95% CI 0.97, 3.13) while HIV coinfection was negatively associated with EPTB (aPR = 0.73, 95% CI 0.55, 0.97). While previous TB history was associated with a lower likelihood of EPTB (aPR = 0.42, 95% CI 0.25, 0.70), it was associated with an increased risk of TB-HIV coinfection (aPR = 1.37, 95% CI 1.10, 1.71). Clinically diagnosed PTB patients were more likely to have TB-HIV coinfection compared to microbiologically confirmed PTB patients (aPR = 1.32, 95% CI 1.02, 1.72).

Conclusions: Increasing proportion of microbiologically confirmed PTB may suggest delayed access to treatment, severe disease and increased risk of intramural transmission. Associations with clinical/demographic factors varied for different types of TB and were not always consistent with what has been previously reported for the general population, necessitating the need to refocus prison TB control/treatment strategies based on context specific epidemiological factors.