Tuberculosis (TB) incidence continued to decline in the United States in 2013, but treating multidrug-resistant (MDR) TB cost an estimated $50 million. Achieving further reductions in TB is likely to require a new focus on the population groups with the highest TB rates, more intensive screening of persons emigrating from (and perhaps even visiting from) countries with high TB incidence, and expanded coordination with health authorities in those countries to improve TB diagnosis and treatment, according to 3 studies by the Centers for Disease Control and Prevention (CDC).
TB Trends: 4 States Have Over Half of US Cases
Negar Niki Alami, MD, from the Epidemic Intelligence Service, CDC, Atlanta, Georgia, and colleagues report in the March 21 issue of Morbidity and Mortality Weekly Report that the 9588 new TB cases reported in 2013 represented a 4.2% decrease in incidence from 2012 but that certain populations continue to be disproportionately affected. Specifically:
Foreign-born persons had a 13 times greater TB incidence than US-born persons and accounted for 64.6% of TB cases in 2013.
More than half of these cases originated from 5 countries: Mexico (20.0% of cases [n = 1233]), the Philippines (12.6% of cases [n = 776]), India (8.0% of cases [n = 495]), Vietnam (7.4% of cases [n = 454]), and China (6.1% of cases [n = 377]).
Analyzing cases by ethnicity, the authors found that the proportion of foreign-born individuals with TB varied greatly, with 95% of Asians, 75% of Hispanics, 40% of blacks, and 23% of whites born outside the United States. Foreign-born persons also accounted for 88.4% of the MDR-TB cases in 2012.
The TB incidence rate among Asians was the highest among all racial/ethnic groups, at almost 26 times greater than among non-Hispanic whites.
Among US-born persons, TB incidence was 6.2 times higher among blacks than among whites.
Four states (California, Texas, New York, and Florida) accounted for 51.3% of TB cases in 2013, despite having only about one third of the US population. Each of these states reported more than 500 cases, and combined, they accounted for 4917 of the 9588 new TB cases reported in 2013.
TB incidence among the homeless is approximately 10 times greater than the overall national TB incidence.
"Continued progress toward TB elimination in the United States will require focused TB control efforts among populations and in geographic areas with disproportionate burdens of TB," the authors write.
According to Dr. Alami, who is an Epidemic Intelligence Service officer with the CDC, most TB cases among foreign-born persons are thought to result from reactivation of latent TB infection acquired previously. TB rates in this subgroup are likely to reflect TB incidence in their countries of origin, and more programs aimed at diagnosing and treating latent TB infection among foreign-born persons may be necessary before TB incidence in the United States can be significantly reduced.
MDR-TB Treatment Costs More Than Lifetime Breast Cancer Care
Researchers led by Suzanne M. Marks, MPH, from the CDC's Division of Tuberculosis Elimination, Atlanta, report in an article published in the May issue of Emerging Infectious Diseases that the average cost of treating each TB case increases with greater resistance. The average direct cost of treating MDR-TB is $134,000 (rising to $430,000 for extensively resistant TB [XDR-TB]) compared with $17,000 for drug-susceptible TB. Adding productivity losses to treatment costs brought the estimated per case cost for treating MDR-TB to $554,000 per case.
Outpatient medications accounted for about 40% of costs, averaging $53,300 for MDR-TB and $164,000 for XDR-TB.
"Because MDR TB treatment lasts >2 years (vs. 6 months for drug-susceptible TB), uses expensive medications, and requires hospitalization for ≈75% of patients (vs. 50% with drug-susceptible TB), it was very costly to treat and manage," the authors write. They compare this to the lifetime cost of care per HIV-infected patient c($380,000) and per breast cancer patient costs ($20,000–$100,000).
According to the CDC researchers, MDR-TB prevention opportunities are limited. They suggest that investing in the "safety net" capacity of public health departments and publicly financed hospitals to quickly diagnose MDR/XDR-TB, isolate patients, and quickly initiate treatment (especially directly observed therapy) will be critical strategies.
Marks and colleagues conclude, "Preventing MDR/XDR TB in the United States will require addressing factors associated with development of drug resistance in countries where foreign-born US patients originate, as well as rapid diagnosis, appropriate regimen selection, robust case management practices, and continued emphasis on [directly observed therapy] in the United States."
Increased TB Testing of Immigrants Already Underway
Some of that coordination is already underway. In an article published in the March 21 issue of the Morbidity and Mortality Weekly Report, Drew. L. Posey, MD, from the Division of Global Migration and Quarantine, National Center for Emerging and Zoonotic Infectious Diseases, CDC, and colleagues describe the implementation of new TB screening requirements for US-bound immigrants and refugees.
Applicants for either an immigrant visa or refugee status are required to undergo a medical examination overseas before being allowed to travel to the United States. In 1991, this included chest radiographs for applicants aged 15 years or older and sputum smears for those with findings suggestive of TB. In 2007, the CDC began requiring sputum cultures and treatment delivered as directly observed therapy.
"In 2012, the year for which the most recent data are available, 60% of the TB cases diagnosed were in persons with smear-negative, but culture-positive, test results. The results demonstrate that rigorous diagnostic and treatment programs can be implemented in areas with high TB incidence overseas," they write.
As an incidental effect of the new requirements, some laboratory facilities and diagnostic capabilities were upgraded. "To fulfill the laboratory culture requirement, new laboratories performing TB cultures were developed in China, India, Kenya, Mexico, Nepal, Thailand, Vietnam, and other countries. In addition, laboratories serving panel physicians in several countries developed the capability to perform drug-susceptibility testing on second-line drugs, which are used to treat [MDR-TB]. These countries include China, Kenya, Nepal, Thailand, and Vietnam. During 2008–2013, 10 training summits were conducted, attended by panel physicians or U.S. Department of State consular officers, representing a total of 101 countries," the authors write.
To further reduce the number of TB cases among foreign-born persons in the United States, the researchers suggest the CDC consider "extending screening to long-term visitors, developing innovative strategies to address the reservoir of latent TB infection in the foreign-born population, and strengthening U.S. follow-up for arriving persons identified overseas as being at risk for TB."
The researchers estimate that the decrease in US TB cases associated with improved overseas TB diagnosis might save more than $15 million/year in US healthcare costs.
The authors have disclosed no relevant financial relationships.
Emerging Infect Dis. 2014;20. Full text
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