WHO Case Definitions

1. Interim Draft Module 5 - September 2008 WHO Case Definitions

2. Project Partners • Collaborative project Funded by the United States Agency for International Development (USAID)

3. Module Overview • Case Definitions • Categories for registering TB case at diagnosis • New • Relapse • Treatment after failure • Treatment after default • Transfer in • Other

4. Learning Objectives Objectives: At the end of this presentation, participants will be able to: • Identify the World Health Organization case definitions for tuberculosis • List the World Health Organization categories for registering TB cases at diagnosis

5. Case Definitions • It is essential that patients be categorized correctly before starting treatment for TB • These standard WHO case definitions guide the determination of the treatment regimen: • Tuberculosis suspect • Case of tuberculosis • Definite case of tuberculosis

6. Case Definitions (2) • Tuberculosis suspect: Any person who presents with symptoms or signs suggestive of TB, in particular a cough of long duration (>2 weeks) • Case of tuberculosis: A patient in whom TB has been bacteriologically confirmed or diagnosed by a clinician  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

7. Case Definitions (3) • Definite case of tuberculosis: A patient with a positive culture for M. tuberculosis complex  In countries where culture is not routinely available, a patient with two sputum smears positive for acid-fast bacilli (AFB) is also considered a “definite” case.

8. Determinants of Case Definition There are four determinants of case definition: • Site of TB disease • Bacteriology (sputum smear positive and smear negative) • Severity of TB disease • History of previous TB treatment

9. Site of Disease • 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

10. Site of Disease (2) • 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

11. Site of Disease (3) • Diagnosis of EPTB should be based on: • 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 tuberculosis chemotherapy • The case definition of an EPTB case with several sites affected depends on the site representing the most severe form of disease • If both pulmonary and EPTB sites involved, classify as PTB

12. Bacteriology(sputum smear-positive and smear-negative) • Defining the AFB smear result in pulmonary cases is important to: • Identify smear positive cases as they are the most infectious and usually have higher rates of mortality • Record, report, and evaluate programme performance  Smear-positive cases are the most practical cases for monitoring bacteriologic response to treatment.

13. Bacteriology (2)(sputum smear-positive and smear-negative) Pulmonary TB: Sputum smear-positive • A patient with two or more sputum specimens with positive smear for AFB • OR: at least one sputum specimen smear positive for AFB and radiographic abnormalities consistent with active PTB as determined by a clinician • OR: at least one sputum smear positive for AFB plus sputum culture positive for M. tuberculosis complex

14. Bacteriology (3) (sputum smear-positive and smear-negative) • A case of PTB that does not meet the definition for sputum smear-positive PTB  Includes cases without sputum smear results which should be relatively rare in adolescent and adult cases but may be more frequent for PTB diagnosed in children Pulmonary TB: Sputum smear-negative

15. Bacteriology (4) (sputum smear-positive and smear-negative) Pulmonary TB: Sputum smear-negative (continued) • Note: In keeping with good clinical and public health practice, diagnostic criteria for sputum smear-negative PTB should include: • At least three sputum specimens negative for AFB, AND • Radiographic abnormalities consistent with active PTB, AND • No response to a course of broad-spectrum non-TB antibiotics, AND • A decision by the clinician to treat with a full course of anti-tuberculosis chemotherapy

16. Severity of TB Disease • Considerations in determining TB disease severity: • Bacillary load • Extent of disease • Anatomical site • A classification of severe disease is given when the anatomical site involved presents: • A significant acute threat to life (e.g. pericardial TB) • A risk of subsequent severe handicap (e.g. spinal TB), OR • Both (e.g. meningeal TB)

17. Severity of TB Disease (2) • Miliary, disseminated TB is considered to be severe • The following forms of EPTB are also classified as severe: • Meningeal • Pericardial • Peritoneal • Bilateral or extensive pleural effusion • Spinal • Intestinal • Genitourinary

18. Severity of TB Disease (3) • The following forms of EPTB are classified as less severe: • Lymph node • Pleural effusion (unilateral) • Bone (excluding spine) • Peripheral joint and skin

19. History of Previous TB Treatment • 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 so as to prescribe them appropriate treatment, and • Provide epidemiological monitoring of the TB epidemic at regional and country levels

20. TB Case Registration Categories • New case: A patient who has never had treatment for TB or who has taken anti-tuberculosis drugs for less than 1 month • Relapse: A patientpreviously treated for TB who has been declared cured or treatment completed, and is diagnosed with bacteriologically positive (smear or culture) tuberculosis • Treatment after Failure: A patient who is started on a re-treatment regimen after having failed previous treatment

21. TB Case Registration Categories (2) • Treatment after Default: A patient who returns to treatment following interruption of treatment for two months or more and is positive bacteriologically • Transfer in: A patient who has transferred from another TB register to continue treatment

22. TB Case Registration Categories (3) • Other: All cases that do not fit the definitions listed on the previous slides. This group includes chronic cases, patients that are sputum smear/culture-positive at the end of a retreatment regimen Although smear-negative PTB and EPTB cases may also be treatment failures, relapses, returns after default or chronic, this should be a rare event supported by pathological or bacteriological evidence

23. TB Case Registration Activity

24. Summary • Every TB patient should be assessed for the four determinants of case definition so they can be classified correctly and begin treatment • Every TB patient should be categorized by case registration at the time of diagnosis