Table 1.
TB diagnostic criteria
| Symptom and x-ray result | Investigation results | Definition |
|---|---|---|
| Symptom positive and typical TB on x-ray | Sputum culture or Xpert positive | Definite TB |
| Sputum smear positive, culture negative/not available and Xpert negative/not available | Probable TB | |
| Sputum smear negative, culture negative/not available and Xpert negative/not available | Possible TB | |
| Symptom positive, possible TB on x-ray (including extra-pulmonary findings) | Sputum culture or Xpert positive | Definite TB |
| Sputum smear positive, culture negative/not available and Xpert negative/not available | Probable TB | |
| Sputum smear negative, culture negative/not available and Xpert negative/not available | Possible TB | |
| Histopathology positive, culture negative/not available and Xpert negative/not available | Probable TB | |
| Other sample culture or Xpert positive | Definite TB | |
| Symptom negative, typical TB on x-ray | Sputum culture or Xpert positive | Definite TB |
| Sputum smear positive, culture negative/not available and Xpert negative/not available | Probable TB | |
| Sputum smear negative, culture and/or Xpert negative | Possible TB | |
| Symptom positive, normal x-ray | Sputum culture positive | Definite TB |
| Sputum smear positive, culture negative/not available and Xpert negative/not available | Possible TB | |
| Sputum smear negative, culture negative/not available and Xpert negative/ not available | Not TB | |
| Histopathology positive, culture negative/not available and Xpert negative/ not available | Probable TB | |
| Other sample culture or Xpert positive | Definite TB | |
| Symptom negative, possible TB on x-ray (including extra-pulmonary findings) | Sputum culture or Xpert positive | Definite TB |
| Sputum smear positive, culture negative/not available and Xpert negative/not available | Possible TB | |
| Sputum smear negative, culture negative/not available and Xpert negative/not available | Possible TB | |
| Histopathology positive, culture negative/not available and Xpert negative/ not available | Probable TB | |
| Other sample culture or Xpert positive | Definite TB |
1A positive GeneXpert is regarded as having the same status as a positive culture result
2Symptoms include the clinical sign of adenopathy. ‘Histopathology’ includes microscopy/cell counts of fluid. These definitions regard the initial evaluation. Some patients with possible TB will be put on treatment. A clearcut response to treatment (e.g. improved symptoms and resolution of a pleural effusion) may be considered enough evidence to change a ‘possible’ to a ‘probable’ case
3For patients who die without recent TB evaluations, a verbal autopsy will be carried out wherever possible. An endpoint committee will review available data and categorise patients as definite, probable or possible TB; no evidence of TB at death; or unknown TB status at death