Dolly Katz

Limited Utility of Name-Based Tuberculosis Contact Investigations among Persons Using Illicit Drugs: Results of an Outbreak Investigation

Persons named by a patient with tuberculosis (TB) are the focus of traditional TB contact investigations. However, patients who use illicit drugs are often reluctant to name contacts. Between January 2004 and May 2005, 18 isoniazid-resistant TB cases with matching Mycobacterium tuberculosis genotypes (spoligotypes) were reported in Miami; most patients frequented crack houses and did not name potentially infected contacts. We reviewed medical records and reinterviewed patients about contacts and locations frequented to describe transmission patterns and make recommendations to control TB in this population. Observed contacts were not named but were encountered at the same crack houses as the patients. Contacts were evaluated for latent TB infection with a tuberculosis skin test (TST). All 18 patients had pulmonary TB. Twelve (67%) reported crack use and 14 (78%) any illicit drug use. Of the 187 contacts evaluated, 91 (49%) were named, 16 (8%) attended a church reported by a patient, 61 (33%) used a dialysis center reported by a patient, and 19 (10%) were observed contacts at local crack houses. Compared to named contacts, observed contacts were eight times as likely to have positive TST results (relative risk = 7.8; 95% confidence interval = 3.8–16.1). Dialysis center and church contacts had no elevated risk of a positive TST result. Testing observed contacts may provide a higher yield than traditional name-based contact investigations for tuberculosis patients who use illicit drugs or frequent venues characterized by illicit drug use.

Epidemiology of Tuberculosis in Young Children in the United States

OBJECTIVES: To estimate tuberculosis (TB) rates among young children in the United States by children’s and parents’ birth origins and describe the epidemiology of TB among young children who are foreign-born or have at least 1 foreign-born parent. METHODS: Study subjects were children <5 years old diagnosed with TB in 20 US jurisdictions during 2005–2006. TB rates were calculated from jurisdictions’ TB case counts and American Community Survey population estimates. An observational study collected demographics, immigration and travel histories, and clinical and source case details from parental interviews and health department and TB surveillance records. RESULTS: Compared with TB rates among US-born children with US-born parents, rates were 32 times higher in foreign-born children and 6 times higher in US-born children with foreign-born parents. Most TB cases (53%) were among the 29% of children who were US born with foreign-born parents. In the observational study, US-born children with foreign-born parents were more likely than foreign-born children to be infants (30% vs 7%), Hispanic (73% vs 37%), diagnosed through contact tracing (40% vs 7%), and have an identified source case (61% vs 19%); two-thirds of children were exposed in the United States. CONCLUSIONS: Young children who are US born of foreign-born parents have relatively high rates of TB and account for most cases in this age group. Prompt diagnosis and treatment of adult source cases, effective contact investigations prioritizing young contacts, and targeted testing and treatment of latent TB infection are necessary to reduce TB morbidity in this population.

Preventing Infectious Pulmonary Tuberculosis Among Foreign-Born Residents of the United States

OBJECTIVES We described risk factors associated with infectious tuberculosis (TB) and missed TB-prevention opportunities in foreign-born US residents, who account for almost two thirds of the nations TB patients. METHODS In a cross-sectional study at 20 US sites of foreign-born persons diagnosed with TB in 2005 through 2006, we collected results of sputum smear microscopy for acid-fast bacilli (a marker for infectiousness) and data on visa status, sociodemographics, TB-related care seeking, and latent TB infection (LTBI) diagnosis opportunities. RESULTS Among 980 persons with pulmonary TB who reported their visa status, 601 (61%) were legal permanent residents, 131 (13.4%) had temporary visas, and 248 (25.3%) were undocumented. Undocumented persons were more likely than permanent residents to have acid-fast bacilli-positive smears at diagnosis (risk ratio = 1.3; 95% confidence interval = 1.2, 1.4). Of those diagnosed 1 year or more after arrival, 57.3% reported LTBI screening opportunities; fewer than 25% actually were. Undocumented persons reported fewer LTBI screening opportunities and were less likely to be tested. CONCLUSIONS Progress toward TB elimination in the United States depends upon expanding opportunities for regular medical care and promotion of LTBI screening and treatment among foreign-born persons.

Tuberculosis Elimination Efforts in the United States in the Era of Insurance Expansion and the Affordable Care Act

The Patient Protection and Affordable Care Act can enhance ongoing efforts to control tuberculosis (TB) in the United States by bringing millions of currently uninsured Americans into the health-care system. However, much of the legislative and financial framework that provides essential public health services necessary for effective TB control is outside the scope of the law. We identified three key issues that will still need to be addressed after full implementation of the Affordable Care Act: (1) essential TB-related public health functions will still be needed and will remain the responsibility of federal, state, and local health departments; (2) testing and treatment for latent TB infection (LTBI) is not covered explicitly as a recommended preventive service without cost sharing or copayment; and (3) remaining uninsured populations will disproportionately include groups at high risk for TB. To improve and continue TB control efforts, it is important that all populations at risk be tested and treated for LTBI and TB; that testing and treatment services be accessible and affordable; that essential federal, state, and local public health functions be maintained; that private-sector medical/public health linkages for diagnosis and treatment be developed; and that health-care providers be trained in conducting appropriate LTBI and TB clinical care.

Mortality Hazard and Survival After Tuberculosis Treatment

OBJECTIVES We compared mortality among tuberculosis (TB) survivors and a similar population. METHODS We used local health authority records from 3 US sites to identify 3853 persons who completed adequate treatment of TB and 7282 individuals diagnosed with latent TB infection 1993 to 2002. We then retrospectively observed mortality after 6 to 16 years of observation. We ascertained vital status as of December 31, 2008, using the Centers for Disease Control and Preventions National Death Index. We analyzed mortality rates, hazards, and associations using Cox regression. RESULTS We traced 11 135 individuals over 119 772 person-years of observation. We found more all-cause deaths (20.7% vs 3.1%) among posttreatment TB patients than among the comparison group, an adjusted average excess of 7.6 deaths per 1000 person-years (8.8 vs 1.2; P < .001). Mortality among posttreatment TB patients varied with observable factors such as race, site of disease, HIV status, and birth country. CONCLUSIONS Fully treated TB is still associated with substantial mortality risk. Cure as currently understood may be insufficient protection against TB-associated mortality in the years after treatment, and TB prevention may be a valuable opportunity to modify this risk.

Tuberculosis Mortality in the United States: Epidemiology and Prevention Opportunities

Rationale: More information on risk factors for death from tuberculosis in the United States could help reduce the tuberculosis mortality rate, which has remained steady for more than a decade. Objective: To identify risk factors for tuberculosis‐related death in adults. Methods: We performed a retrospective study of 1,304 adults with tuberculosis who died before treatment completion and 1,039 frequency‐matched control subjects who completed tuberculosis treatment in 2005 to 2006 in 13 states reporting 65% of U.S. tuberculosis cases. We used in‐depth record abstractions and a standard algorithm to classify deaths in persons with tuberculosis as tuberculosis‐related or not. We then compared these classifications to causes of death as coded in death certificates. We used multivariable logistic regression to calculate adjusted odds ratios for predictors of tuberculosis‐related death among adults compared with those who completed tuberculosis treatment. Results: Of 1,304 adult deaths, 942 (72%) were tuberculosis related, 272 (21%) were not, and 90 (7%) could not be classified. Of 847 tuberculosis‐related deaths with death certificates available, 378 (45%) did not list tuberculosis as a cause of death. Adjusting for known risks, we identified new risks for tuberculosis‐related death during treatment: absence of pyrazinamide in the initial regimen (adjusted odds ratio, 3.4; 95% confidence interval, 1.9‐6.0); immunosuppressive medications (adjusted odds ratio, 2.5; 95% confidence interval, 1.1‐5.6); incomplete tuberculosis diagnostic evaluation (adjusted odds ratio, 2.2; 95% confidence interval, 1.5‐3.3), and an alternative nontuberculosis diagnosis before tuberculosis diagnosis (adjusted odds ratio, 1.6; 95% confidence interval, 1.2‐2.2). Conclusions: Most persons who died with tuberculosis had a tuberculosis‐related death. Intensive record review revealed tuberculosis as a cause of death more often than did death certificate diagnoses. New tools, such as a tuberculosis mortality risk score based on our study findings, may identify patients with tuberculosis for in‐hospital interventions to prevent death.

Evaluating latent tuberculosis infection diagnostics using latent class analysis

Background Lack of a gold standard for latent TB infection has precluded direct measurement of test characteristics of the tuberculin skin test and interferon-γ release assays (QuantiFERON Gold In-Tube and T-SPOT.TB). Objective We estimated test sensitivity/specificity and latent TB infection prevalence in a prospective, US-based cohort of 10 740 participants at high risk for latent infection. Methods Bayesian latent class analysis was used to estimate test sensitivity/specificity and latent TB infection prevalence among subgroups based on age, foreign birth outside the USA and HIV infection. Results Latent TB infection prevalence varied from 4.0% among foreign-born, HIV-seronegative persons aged <5 years to 34.0% among foreign-born, HIV-seronegative persons aged ≥5 years. Test sensitivity ranged from 45.8% for the T-SPOT.TB among foreign-born, HIV-seropositive persons aged ≥5 years to 80.7% for the tuberculin skin test among foreign-born, HIV-seronegative persons aged ≥5 years. The skin test was less specific than either interferon-γ release assay, particularly among foreign-born populations (eg, the skin test had 70.0% specificity among foreign-born, HIV-seronegative persons aged ≥5 years vs 98.5% and 99.3% specificity for the QuantiFERON and T-SPOT.TB, respectively). The tuberculin skin test’s positive predictive value ranged from 10.0% among foreign-born children aged <5 years to 69.2% among foreign-born, HIV-seropositive persons aged ≥5 years; the positive predictive values of the QuantiFERON (41.4%) and T-SPOT.TB (77.5%) were also low among US-born, HIV-seropositive persons aged ≥5 years. Conclusions These data reinforce guidelines preferring interferon-γ release assays for foreign-born populations and recommending against screening populations at low risk for latent TB infection. Trial registration number NCT01622140.