Case definitions

Clinical description

Bacteriologically confirmed TB Biological specimen is positive by smear microscopy, culture or WRD (e.g. Xpert MTB/RIF, Line Probe Assay). All such cases should be notified, regardless of whether TB treatment has started.

Clinically diagnosed TB case Does not fulfil the criteria for bacteriological confirmation but has been diagnosed with active TB by a clinician or other medical practitioner who has decided to give the patient a full course of TB treatment. This definition includes diagnoses based on X-ray abnormalities; Urinary LAM in immunosuppressed HIV infected individuals with the prerequisite CD 4 range or WHO stage 3 and 4 conditions; or suggestive histology and extra pulmonary cases without laboratory confirmation. Clinically diagnosed cases subsequently found to be bacteriologically positive (before or after starting treatment) should be reclassified as bacteriologically confirmed.

Bacteriologically confirmed or clinically diagnosed cases of TB are also classified by:

• Anatomical site of disease
• History of previous treatment
• Drug Susceptibility Patterns i.e. Drug Sensitive or Drug Resistant TB
• HIV status.

Classif ication based on anatomical site of disease Pulmonary tuberculosis (PTB)

Any bacteriologically confirmed or clinically diagnosed case of TB involving the lung parenchyma or the tracheobronchial tree, while in children PTB includes Hilar and Subcarinal Lymph node involvement. Miliary TB is classified as PTB because there are lesions in the lungs.

Tuberculous intra-thoracic lymphadenopathy (mediastinal and/or hilar) or tuberculous pleural effusion, without radiographic abnormalities in the lungs, constitutes a case of extrapulmonary TB.

A patient with both pulmonary and extra pulmonary TB should be classified as a case of PTB.

Extrapulmonary tuberculosis (EPTB)

Any bacteriologically confirmed or clinically diagnosed case of TB involving organs other than the lungs, e.g. pleura, lymph nodes (in the case of children peripheral lymph nodes such as cervical lymph nodes. Intrathoracic lymph node groups such as hilar and subcarinal lymph nodes are classified as PTB), abdomen, genitourinary tract, skin, joints and bones, meninges.

16 National Tuberculosis Control Programme Classif ications based on history of previous TB treatment Classifications based on history of previous TB treatment are slightly different from those previously published. They focus only on history of previous treatment and are independent of bacteriological confirmation or site of disease.

• New patients have never been treated for TB or have taken anti-TB drugs for less than

1 month.

• Previously treated patients have received 1 month or more of anti-TB drugs in the past.

They are further classified by the outcome of their most recent course of treatment as follows:

 Relapse patients have previously been treated for TB, were declared cured or treatment completed at the end of their most recent course of treatment and are now diagnosed with a recurrent episode of TB (either a true relapse or a new episode of TB caused by reinfection).

 Treatment after failure patients are those who have previously been treated for TB and whose treatment failed at the end of their most recent course of treatment.

 Treatment after loss to follow-up patients have previously been treated for TB and were declared lost to follow-up at the end of their most recent course of treatment. (These were previously known as treatment after default patients.)

 Other previously treated patients are those who have previously been treated for TB but whose outcome after their most recent course of treatment is unknown or undocumented.

• Patients with unknown previous TB treatment history do not fit into any of the

categories listed above.

• New and relapse cases of TB are incident TB cases.

Treatment outcomes

• Cured A pulmonary TB patient with bacteriologically confirmed TB at the beginning of treatment

who was smear- or culture-negative in last month of treatment and on at least one previous occasion.

• Treatment completed A TB patient who completed treatment without evidence of failure BUT with

no record to show that sputum smear or culture results in last month of treatment and on at least one previous occasion were negative, either because tests were not done or because results are unavailable.

• Treatment failed A TB patient whose sputum or culture is positive at month 5 or later during

treatment.

• Died A TB patient who dies for any reason before starting or during treatment.
• Lost to follow-up A TB patient who did not start treatment or whose treatment was interrupted for

2 or more consecutive months.

• Not evaluated A TB patient for whom no treatment outcome is assigned. This includes cases

“transferred out” to another treatment unit as well as cases for whom the treatment outcome is unknown to the reporting unit.

• Treatment success. The sum of cured and treatment completed.

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