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World Health Organization TB Case Definitions

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1 World Health Organization TB Case Definitions
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Module Version Module 4 – March 2010 World Health Organization TB Case Definitions Instructor’s Notes Module 4: World Health Organization (WHO) Case Definitions Module Time: Approximately 70 minutes This module has been divided into the following sections: Overview and TB Case Definitions (slides 3-9) – 10 min. Categories for Classifying TB Cases (slides 10-23) – 20 min. TB Case Registration Groups and Summary (slides 24-29) –40 min. (includes a 30 min. activity on slide 28) Resource documents: Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV (CTBG) Chapter 4 Interactive options: Ideas for interactive discussions are offered on many of the slides in this module. Participant discussion can enhance active learning, but will add more time to the lecture and must be planned for. Evaluation questions may be attached or inserted within presentation for discussion purposes, or alternately, combined with questions from other modules to produce an evaluation tool. Additional Material: Slides containing related material may be found in the following modules: 1, 5, 7, 11.

2 Funded by the Health Resources and Services Administration (HRSA)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Project Partners Module Version Funded by the Health Resources and Services Administration (HRSA)

3 Module Overview TB Case Definitions
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Module Overview Module Version TB Case Definitions Categories for Classifying TB Cases Site of Disease Bacteriologic Result HIV Status History of Prior Treatment TB Case Registration Groups Overview and TB Case Definitions (slides 3-9) – 10 min. [Overview: Review the slide content] [Image credit: Lung Health Image Library/Gary Hampton]

4 Learning Objectives Objectives: At the end of this presentation,
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Learning Objectives Module Version Objectives: At the end of this presentation, participants will be able to: Define TB cases utilizing the World Health Organization case definitions for tuberculosis State the four key features important to classifying TB cases Categorize TB cases utilizing the World Health Organization registration groupings [Review objectives from the slide content]

5 Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV
Module Version TB Case Definitions [Image credits: Lung health Image Library/Jad Davenport (top) and Jan van den Hombergh (bottom)]

6 Why do we define and categorize TB cases?
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Module Version Why do we define and categorize TB cases? [Pose question to the participants] [Write participant responses on flip chart, poster, or white board]

7 Purpose of TB Case Definitions
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Purpose of TB Case Definitions Module Version Correct categorization of patients before starting treatment for TB is essential: for proper patient registration and case notification to select the appropriate treatment regimen to standardize the process of data collection for TB control to evaluate the proportion of cases according to site, bacteriology, and treatment history for cohort analysis of treatment outcomes to accurately monitor trends and evaluate the effectiveness of TB programs [Review the slide content] To accurately monitor trends and evaluate the effectiveness of TB programs within and across districts, countries and global regions Regimens are discussed in Chapter 7 of the Caribbean TB guidelines and in Module 7 Lets review these case definitions [Click: Slide Animation]

8 Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV
TB Case Definitions Module Version Tuberculosis suspect — Any person who presents with symptoms or signs suggestive of TB (e.g., a cough of long duration, > 2 weeks) Case of tuberculosis a definite case of TB (defined next slide) or diagnosed by a health worker with the plan to treat with a full course of anti-TB treatment  Any person started on TB treatment should be recorded as a case. Incomplete “trial” TB treatment should not be given as a method for diagnosis TB case definitions are based on the level of certainty of the diagnosis, and whether or not laboratory confirmation is available These are the standard WHO case definitions; [review slide content] A TB Suspect is any person who presents with symptoms or signs suggestive of TB. The most common symptom of pulmonary TB is a productive cough usually lasting over two weeks without another known cause, and which may be accompanied by other symptoms: respiratory symptoms such as shortness of breath, chest and back pains, hemoptysis and/or constitutional symptoms such as loss of appetite, weight loss, fever, night sweats, and fatigue The definition of “TB suspect” may depend on other local factors, such as patient’s age, HIV status of the individual and prevalence in the population, prevalence of TB in the population, etc. Case of tuberculosis. A patient in whom TB has been bacteriologically confirmed, or if no bacteriologic confirmation, a health worker must both make the diagnosis and decide to treat the patient with a full course of anti-TB treatment. This definition is updated from the prior WHO Treatment guidelines, 3rd edition. The prior guidelines did not require the decision to treat with a full course of anti-TB therapy [Click: Slide Animation]

9 Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV
TB Case Definitions (2) Module Version Definite case of tuberculosis: A patient with M. tuberculosis complex identified from a clinical specimen by culture or newer method (e.g., nucleic acid amplification, molecular beacon or line probe assays)  In countries where M. tuberculosis cannot routinely be identified, a pulmonary case with one or more initial sputum smears positive for acid-fast bacilli (AFB) is also considered a “definite” case [Review the slide content] In countries where laboratories cannot yet routinely identify Mycobacterium tuberculosis complex, a pulmonary case with one or more initial sputum smear examinations positive for acid-fast bacilli (AFB) is also considered a "definite" case, as long as there is a functional external quality assurance (EQA) system with blind rechecking. (this definition is a change from the prior WHO Treatment guidelines 3rd edition when two positive smears were required before a patient could be considered a definite case) [Click: Slide Animation]

10 Categories for Classifying TB Cases
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Module Version Categories for Classifying TB Cases Categories for Classifying TB Cases (slides 10-23) – 20 min. [Image credit: Francis J. Curry National Tuberculosis Center]

11 TB Case Classifications
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV TB Case Classifications Module Version TB cases are also classified according to: Anatomical site of TB disease Bacteriologic results (including drug resistance) History of previous TB treatment HIV status of the patient We define cases also by these four key features: [Review slide content] Severity of disease is no longer included as a feature of the case definition We’re going to review each one in more detail and then practice applying them to different patients in a case study activity [Click: Slide Animation]

12 Anatomical Site of Disease
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Anatomical Site of Disease Module Version Pulmonary Tuberculosis (PTB): Refers to disease involving the lung parenchyma A patient with both pulmonary and extra-pulmonary TB constitutes a case of PTB Miliary TB is classified as PTB because there are lesions in the lungs With a few exceptions, defining the site of TB disease is primarily for epidemiologic purposes and for identifying infectious patients (e.g., those with pulmonary or laryngeal TB) rather than for determining treatment regimen or approach to management While tuberculosis can occur in almost any part of the body, the site of TB disease is generally classified as either pulmonary or extra-pulmonary [Review slide content] [Image credits: Francis J. Curry National Tuberculosis Center]

13 Anatomical Site of Disease (2)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Anatomical Site of Disease (2) Module Version Extra-pulmonary Tuberculosis (EPTB): Refers to TB disease of organs other than the lungs. Therefore the following constitute a case of EPTB: Tuberculous intrathoracic lymphadenopathy (mediastinal and/or hilar) Tuberculous pleural effusion, without radiographic abnormalities in the lungs Extrathoracic TB [Review slide content] Of note, EPTB is considered WHO clinical stage 4 for HIV infection and related disease. (Covered in Chapter 9 of the Caribbean TB guidelines) [Interactive Option: Invite participants to describe examples of EPTB sites they’ve seen in their practice]

14 Anatomical Site of Disease (3)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Anatomical Site of Disease (3) Module Version Diagnosis of EPTB should be based on a decision to treat with a full course along with: One culture-positive specimen; or Histological specimen; or Strong clinical evidence consistent with active EPTB and a decision to treat with a full course of anti-TB treatment Where several EPTB sites are involved, the case definition depends on the site representing the most severe form of disease Classify as PTB if both pulmonary and extra-pulmonary sites involved [Review the slide content] [Interactive Option: Ask if there are any questions about defining cases by site of disease] Unless the EPTB case is confirmed to contain M. tuberculosis by culture or newer method, it does not meet the “definite case” definition [Click: Slide Animation]

15 Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV
Bacteriologic Result Module Version Includes smear, culture and newer methods for identification of M. tuberculosis Defining the AFB smear result is important : to identify smear-positive cases = most infectious; most likely to transmit TB to others to identify sputum smear-negative cases, especially HIV positive persons to record, report, and evaluate program performance  Bacteriologic monitoring for treatment response is most practical in smear-positive patients [Review the slide content] Smear-positive cases are generally the focus for infection control measures and for contact investigations. (Can refer to page 21 in the Caribbean TB guidelines) Smear-negative, HIV-positive cases have a higher mortality rate than smear-positive PTB cases.  It’s thought that delays in diagnosis may be an important cause for the increased mortality in smear-negative TB patients with HIV [Click: Slide Animation]   [Source - World Health Organization. Improving the Diagnosis and Treatment of Smear-negative Pulmonary and Extrapulmonary Tuberculosis Among Adults and Adolescents: Recommendations for HIV-prevalent and Resource-constrained Settings [WHO/HTM/TB / , WHO /HIV/ ]]

16 Bacteriologic Result (2)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Bacteriologic Result (2) Module Version Pulmonary TB: Sputum smear-positive Where there is a functional EQA system: A patient with one or more sputum specimens that are AFB smear-positive is considered a PTB case [Review the slide content] A case of PTB is considered smear positive if one or more sputum smear examinations at the start of treatment is positive for AFB, as long as there is a functional external quality assurance (EQA) system with blind rechecking. (this definition is a change from the prior WHO Treatment guidelines 3rd edition) Note that the definition of a new sputum smear-positive pulmonary TB case is based on the presence of at least one acid fast bacilli (AFB+) in at least one sputum sample in countries with a well functioning external quality assurance (EQA) system (http://www.who.int/tb/dots/laboratory/policy/en/index1.html) Under program conditions, when microscopy laboratory services are available and diagnostic criteria are properly applied, PTB sputum smear-positive cases represent at least 65% of the total PTB cases in adults, and 50% or more of all TB cases. These proportions may be lower, however, in high HIV incidence populations

17 Bacteriologic Result (2)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Bacteriologic Result (2) Module Version Pulmonary TB: Sputum smear-positive Where there is not yet a functional EQA system, then one of the following apply at treatment start: > 2 sputum specimens are AFB smear-positive; or at least 1 sputum specimen is AFB smear-positive and radiographic abnormalities consistent with active PTB are present and determined by a clinician; or at least one sputum specimen is AFB smear-positive plus culture is positive for M. tb [Review the slide content] It’s important to remember that these definitions are highly tied to laboratory practice so knowing whether the laboratory that has tested the specimen has a functional external quality assurance process will be essential to making the diagnosis In situations where the laboratory does not yet have a functional EQA system, the prior WHO definition for sputum-smear positive PTB still holds and is as described in this slide

18 Bacteriologic Result (3)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Bacteriologic Result (3) Module Version Pulmonary TB: Sputum smear-negative At least 2 sputum specimens are negative for AFB at start of treatment No specimen is smear positive Obtain TB culture for all smear-negative cases [Review the slide content] A PTB case can be considered smear-negative if at least 2 sputum specimens are negative for AFB at the start of treatment in countries with a functioning EQA system, where the workload is very high, and human resources are limited [Image credit: Francis J. Curry National TB Center]

19 Bacteriologic Result (4)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Bacteriologic Result (4) Module Version Pulmonary TB: Sputum smear-negative Defined as: Smear-negative but culture-positive for M.tb; or Meet the following criteria: decision by a clinician to treat with a full course of anti-tuberculosis chemotherapy, and radiographic abnormalities consistent with active PTB, and either: laboratory or strong clinical evidence of HIV infection or no response to a course of broad-spectrum non-TB antibiotics (if HIV-negative or status unknown) The criteria for defining a sputum smear-negative PTB case has changed: [Review slide content] For all smear-negative cases of PTB, TB culture should be performed. This is particularly important in high HIV-prevalence settings (> 1% in pregnant women or > 5% in TB patients) In the absence of culture, a chest X-ray is necessary to document cases of sputum smear-negative PTB along with commitment to treat with a full course of anti-TB therapy For last bullet, HIV status unknown only applies to low HIV-prevalence areas NOTE: Fluoroquinolones are bactericidal for M. tuberculosis complex and therefore, should be avoided in the treatment of respiratory tract infections when TB is also on the differential diagnosis. Fluoroquinolone therapy in such settings (e.g., presumed non-TB, community acquired pneumonia that later turned out to be TB indeed) has been associated with delays in TB diagnosis, initiation of appropriate anti-tuberculosis treatment and acquired resistance to the fluoroquinolones [Click: Slide Animation]

20 Bacteriologic Result (5)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Bacteriologic Result (5) Module Version Pulmonary TB: Smear not done PTB cases without smear results are no longer classified as smear-negative! Classify as “smear not done” on the TB Register and annual survey The definition of sputum smear-negative case no longer includes cases without sputum smear results. These cases should now be classified as “smear not done” on the TB Register and on the annual surveys submitted to CAREC and WHO PTB cases without smear results often are pediatric cases although attempts to collect a specimen for smear and culture should be made [Interactive option: Ask participants] “What type of specimens can you collect on suspect pediatric PTB cases to assess for AFB smear and culture?” Answers might include: sputum for older children (either spontaneously produced or induced sputa), gastric aspirate (early morning after overnight fast), and bronchoalveolar lavage fluid This radiograph shows extensive miliary disease which predominates in the upper lung zones. Miliary TB is classified as PTB as there are lesions in the lungs. This film also shows associated right sided paratracheal adenopathy (arrow) [Image credit: Francis J. Curry National TB Center/Ann M. Loeffler, MD]

21 Bacteriologic Result (6)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Bacteriologic Result (6) Module Version ISTC Standard 3: Extrapulmonary Specimens For all patients suspected of having extrapulmonary TB, appropriate specimens from the suspected sites of involvement should be obtained for microscopy, culture and histopathological examination. For all patients suspected of having extrapulmonary TB (includes adults, adolescents, and children), appropriate specimens from the suspected sites of involvement should be obtained for microscopy, culture and histopathological examination Generally, the number and concentration of M. tb organisms is lower in extrapulmonary sites compared to the number found in active TB in the lungs. For this reason, acid-fast bacilli are less commonly seen by microscopy in specimens from extrapulmonary sites and culture is more important for making a diagnosis of TB If tissue biopsy material is obtained, diagnosis of TB may also be suggested by histopathologic demonstration of appropriate granulomatous lesions Examination of sputum and chest radiograph should be considered to rule out simultaneous pulmonary TB, especially in persons with HIV infection Participant may refer to ISTC document page 26 [Image credit: IUATLD International Standards for Tuberculosis Care, 2009

22 Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV
HIV Status Module Version Determining and recording HIV status for TB cases is critical for: Making treatment decisions Monitoring trends Assessing program performance The 2006 updated TB Register and TB Treatment Card include dates for: HIV testing Co-trimoxazole initiation ART initiation [Review the slide content] Interventions for TB Register and treatment care are discussed more fully in Chapter 9

23 History of Previous TB Treatment
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV History of Previous TB Treatment Module Version A case should be defined according to whether or not the patient has previously received TB treatment in order to: Identify patients at increased risk of acquired drug resistance Provide epidemiological monitoring of the TB epidemic and program performance at regional and country levels [Review the slide content] Patients who have received TB treatment in the past are important to identify because: they are at increased risk for drug resistance require drug susceptibility testing , and so proper treatment can be prescribed The distinction between new and previously treated cases is also important for epidemiologic monitoring at regional and country levels – this information will enable the National TB Program to advocate and plan for needed resources, drugs, diagnostics, etc. [Image credit: Lung Health Image Library/Gary Hampton]

24 TB Case Registration Groups
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Module Version TB Case Registration Groups TB Case Registration Groups and Summary (slides 24-29) –40 min. (includes a 30 min. activity on slide 28) [Image credit: Francis J. Curry National Tuberculosis Center/Ann Raftery]

25 TB Case Registration Groups
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV TB Case Registration Groups Module Version New case: A patient who has never had treatment for TB or who has taken anti-tuberculosis drugs for less than 1 month Previously Treated case: A patient who has received a month or more of anti-TB drugs in the past (with positive or negative bacteriology) Case is further classified by outcome of most recent course of treatment  No “chronic” category The WHO categories for TB case registration at diagnosis are: [Review the slide content] New Case: [review definition]. These patients may have positive or negative bacteriology and may have disease at any anatomical site Previously Treated: [review definition] These patients may also have disease at any anatomical site (PTB or EPTB). These cases are further classified by outcome which is covered in the next slide There is no longer a “chronic” category. Patient’s who are smear-positive at the end of (or returning from) as second or subsequent course of treatment are now classified by the outcome of their most recent re-treatment course: relapsed, defaulted, or failed [Click: Slide Animation]

26 TB Case Registration Groups (2)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV TB Case Registration Groups (2) Module Version Previously treated cases Relapse: A patient previously treated for TB who has been declared cured or treatment completed, and is diagnosed with bacteriologically positive TB (smear, culture or newer means of identifying M.tb) Treatment after Failure: A patient who is started on a re-treatment regimen after having failed previous treatment Treatment after Default: A patient who returns to treatment following interruption of treatment for > 1 month and is positive bacteriologically As mentioned, all previously treated cases should be further classified by outcome of most recent course of treatment. These classifications include: [review slide content] Treatment after Failure: A patient who is started on a re-treatment regimen after having failed previous treatment. This classification is used for patients who are identified as treatment failures during the course of treatment and are subsequently switched to a re-treatment regimen (e.g., re-treatment is started for the same episode of disease in which the patient has been identified as a treatment failure) Treatment after Default: This is a patient who returns to treatment and is bacteriologically positive following an interruption of treatment for one month or more. It’s important to note that while WHO defines default as an interruption in treatment for ≥2 months, the Pan American Health Organization considers an interruption of ≥1 month to represent default for practical reasons Can refer participants to Chapter 12, Table 28 on page 139 of the Caribbean TB guidelines for definition of treatment failure [Click: Slide Animation]

27 TB Case Registration Groups (3)
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV TB Case Registration Groups (3) Module Version Transfer in: A patient who has transferred from another TB register to continue treatment Other: All cases that do not fit the previous definitions. This includes: Previous treatment history is unknown Previously treated, but outcome is unknown Returned to treatment with: smear-negative PTB bacteriologically negative EPTB [Review the slide content] NOTE: Reinforce that patients whose sputum is smear-positive at the end of (or returning from) a second or subsequent course of treatment are no longer defined as “CHRONIC”. They should be classified by the outcome of their most recent re-treatment course (e.g., relapsed, defaulted or failed) [Click: Slide Animation] [Image credit: Lung Health Image Library/Gary Hampton]

28 Activity TB Case Registration
Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV Module Version TB Case Registration Activity Allow 30 minutes to complete this activity. Refer participants to Worksheet 4.1 Divide large group into smaller groups of 4-5 participants/group Each group will pick a recorder and a reporter Groups will have 20 min.’s to discuss each case together and answer the related questions Reconvene to large group after 20 minutes to review answers to each case. Rotate between groups for report back to large group

29 Caribbean Guidelines for the Prevention, Treatment, Care, and Control of Tuberculosis and TB/HIV
Summary Module Version Every TB patient should be assessed for the four key features of case definition so they can be classified correctly and begin treatment Every TB patient should have TB case registration group determined prior to initiation of TB treatment [Review the slide content] [Interactive option: Ask participants to recall what the four key features for case definition are] Answers should include: 1) site of disease, 2) bacteriologic results, 3) history of prior treatment, and 4) HIV status


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