Tuberculosis: An update for Primary care physicians - Todd Pollack, M.D

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Outline of Tuberculosis - An update for Primary care physicians: Epidemiology of tuberculosis; diagnosis and treatment of latent tuberculosis infection (LTBI); diagnosis of pulmonary tuberculosis, including new diagnostics; Overview of tuberculosis treatment.

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Nội dung Text: Tuberculosis: An update for Primary care physicians - Todd Pollack, M.D

Tuberculosis: An Update for Primary Care Physicians Todd Pollack, M.D. Deputy Medical Director, HAIVN Clinical Instructor in Medicine, Harvard Medical School Beth Israel Deaconess Medical Center 1
Outline  Epidemiology of tuberculosis  Diagnosis and treatment of latent tuberculosis infection (LTBI)  Diagnosis of pulmonary tuberculosis, including new diagnostics  Overview of tuberculosis treatment 2
Global Burden of TB, 2010 Estimated Estimated number of cases number of deaths 8.8 million 1.1 million All forms of TB (range: 8.5–9.2 million) (range: 0.9–1.2 million) 1.1 million (13%) 350,000 HIV-associated TB (Range: 1.0-1.2 million) (range: 320,000-390,000) Global tuberculosis control: WHO report 2011. 3
TB cases, by region Majority of cases in 2010 occurred in Asia (59%) Global tuberculosis control: WHO report 2011. 4
Estimated TB Incidence Rates, 2010 Vietnam ranks 12 / 22 countries with the highest burden of TB 5 Global tuberculosis control: WHO report 2011.
TB Epidemiology in Vietnam, 2010 2010 Country Data Multi-drug resistant TB:  Estimated new cases:  2.7% of new TB 180,000 cases  Estimated TB deaths:  19% of re-treatment 29,000 cases  Case detection rate: 54% (43-71) Global tuberculosis control: WHO report 2011 6
Latent TB Infection (LTBI)  In most individuals, TB infection is contained initially by host defenses, and infection remains latent.  In Vietnam, an estimated 50-60% of the population has latent TB infection*  Identification and treatment of LTBI can reduce the risk of development of disease by as much as 90 percent *Source: Lien LT, et al. (2009) Prevalence and Risk Factors for Tuberculosis Infection among Hospital Workers in Hanoi, Viet Nam. PLoS ONE 4(8): e6798 7
Diagnosis of LTBI Advantages Disadvantages Tuberculin skin • Inexpensive • Requires follow-up test (TST) • Historical “gold visit for reading standard” • Reading is prone to subjective exam • False positives with recent BCG vaccine, non-TB mycobacteria Interferon • Requires a single • Limited data gamma release patient visit • Expensive assay (IGRA)* • Results available • Errors in collecting within 24 hours and transporting • BCG vaccination blood can decrease does not cause accuracy false positive * WHO does not recommend the use of IGRAs in low and middle income countries. 8
Case Scenario Duc is a 30 year-old man who is found to have latent TB infection (LTBI) during an employment health exam. He has no known contact with an active TB case. He is healthy with no medical problems. His employer also requires an HIV antibody test and his result is pending. 9
Question #1 What is his approximate risk for developing active TB if he is HIV negative? and what is his risk if he is HIV positive? a) Risk is same for both: 10% over lifetime b) HIV (-): 10% over lifetime; HIV (+): 10% per year c) HIV (-): 10% per year; HIV (+): 10% over lifetime 10
Progression to TB Disease (1) TB and HIV People who are infected with both M. tuberculosis and HIV are much more likely to develop TB disease TB infection TB infection and HIV infection and NO risk factors (pre-Highly Active Antiretroviral Treatment [HAART]) Risk is about 5% in the Risk is about 7% to 10% first 2 years after PER YEAR, a very high infection and about 10% risk over a lifetime over a lifetime Source: CDC Self-Study Modules on Tuberculosis, 2010
Progression to TB Disease (2) Some conditions increase probability of LTBI progressing to TB disease • HIV infection • Injection drug use • Recent TB infection • Underweight or • History of prior, untreated malnourished TB or fibrotic lesions on • Silicosis chest x-ray • Diabetes mellitus • Solid organ transplantation • Chronic renal failure or on • Prolonged therapy with hemodialysis corticosteroids or other • Carcinoma of head or neck immunosuppressants • Gastrectomy or jejunoilial bypass 12 Source: CDC Self-Study Modules on Tuberculosis, 2010
Evaluation of Persons with Positive TST or IGRA Person has a positive test for TB infection TB disease ruled out Consider for LTBI treatment Person accepts and is able to If person refuses or is unable to receive treatment of LTBI receive treatment for LTBI, follow-up TST or IGRA and serial chest radiographs are unnecessary Develop a plan of treatment with patient to ensure adherence Educate patient about the signs and symptoms of TB disease Source: CDC Self-Study Modules on TB, 2010 13
Question #2 Assuming his HIV antibody test is negative, what is a preferred option for treatment of LTBI is this patient? a) Rifampin daily for 4 months b) Isoniazid daily for 9 months c) Rifampin plus pyrazinamide daily for 2 months d) Isoniazid plus rifapentine weekly for 3 months 14
Treatment Regimens for LTBI Drug(s) Duration Interval Minimum Doses Isoniazid 9 months Daily 270 Twice weekly* 76 6 months Daily 180 Twice weekly* 52 Isoniazid & 3 months Once weekly* 12 Rifapentine  Rifampin 4 months Daily 120 # Option equal to 9-month INH regimen in * Use Directly Observed certain groups (healthy patients, ≥ 12 years old, Therapy (DOT) at higher risk for developing TB) 15 Source: Recommendations for Use of an Isoniazid-Rifapentine Regimen with Direct Observation to Treat Latent Mycobacterium tuberculosis Infection, MMWR, 2011
Case Scenario After discussion with his physician, Duc elects not to take treatment for latent TB infection. One year later, he presents to the clinic with 2 weeks of fever, cough, and night sweats. 16
Question #3 What diagnostic tests should be ordered, if available, to evaluate for pulmonary TB? a) Chest x-ray and sputum smear for AFB b) Chest x-ray, sputum smear for AFB and molecular testing (nucleic acid amplification) c) Chest x-ray, sputum smear for AFB, sputum culture for AFB, and molecular testing d) Chest x-ray, sputum smear for AFB, sputum culture for AFB, molecular testing, and drug susceptibility testing (if culture positive) 17
Diagnosis of Pulmonary TB History and Exam Chest Radiograph Sputum AFB smear and culture Nucleic Acid Amplification (NAA) 18
TB Chest Radiograph Distinguishing features: 1) Predilection for upper lobes  Apical and posterior segments 2) Tendency for cavitation Radiographic Manifestations of Tuberculosis: A 19 Primer for Clinicians, 2nd Edition, June 2006
Diagnosis of Pulmonary TB Sputum AFB Smear and Culture  Sputum AFB smear • Most rapid and inexpensive TB diagnostic tool • Obtain 3 sputum specimens • Sputum can be collected spontaneously or by induction  AFB Culture • Higher sensitivity than microscopy  Smear: 45-80%; Culture: 80-98% • Allows for drug susceptibility testing and species identification • Better for monitoring treatment response 20