title: Impact of tuberculosis control measures and crowding on the incidence of tuberculous infection in Maryland prisons.
abstract: Our aim was to determine the incidence of tuberculin skin test (TST) conversion in the Maryland state correctional system. We conducted a historical longitudinal cohort study. A sample of 1,289 inmates, incarcerated in 16 of 23 prisons, who had a negative TST and a second test within 24 months was selected. The incidence of recent conversion was 6.3 per 100 person-years. Risk factors for conversion included high prison-population density (relative risk [RR] = 2.4; 95% confidence interval [CI], 1.5-3.8) and incarceration in a higher-security institution (RR = 2.4; 95% CI, 1.4-4.3). Incarceration in an institution with higher levels of isoniazid prophylaxis (> 65% of TST positives) reduced the risk of infection by 50% (RR = 0.5; 95% CI, 0.3-0.7). Crowding was strongly correlated with risk of conversion (r = 0.83; P < .001), while rates of isoniazid prophylaxis initiation were inversely correlated with risk of infection (r = -0.82; P < .001). In stepwise regression, higher prison-population density was the strongest predictor of increased infection. In a final model, inclusion of the rate of isoniazid prophylaxis initiation reduced the risk associated with crowding (RR = 1.4; P = .4). Annual screening programs for prisons can identify recent conversions that may not otherwise be detected.
authors.affiliation: National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australia.
authors.forename: C R
authors.initials: CR
authors.lastname: MacIntyre
authors.forename: N
authors.initials: N
authors.lastname: Kendig
authors.forename: L
authors.initials: L
authors.lastname: Kummer
authors.forename: S
authors.initials: S
authors.lastname: Birago
authors.forename: N M
authors.initials: NM
authors.lastname: Graham
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003441:Crowding; D015658:HIV Infections / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007538:Isoniazid / Q000627:therapeutic use; D008137:Longitudinal Studies; D008297:Male; D008396:Maryland; D015995:Prevalence; D011330:Prisons; D014376:Tuberculosis / Q000453:epidemiology* / Q000517:prevention & control
chemical_list: D007538:Isoniazid