DSSA Guidelines on TB Prophylaxis and Therapy in the context of use of anti TNF drugs and other biologics where used in South Africa.
1) Ensure the appropriate indications for use
2) Unique problems faced in the South African Situation.
b) Latency – It is crucial to determine the latency status pre use of biologic therapy.
Data suggests that in immuno-compromised patients, treatment with prophylaxis can reduce TB by 70% when patients are compliant.
Definition and diagnosis of the LATENT state. This implies treatment is essential
Assessment of Lantency
Mantoux (TST) – the most essential component
- Induration > 5mm = positive (induration.) =and implies latent TB.
- All new patients to be tested BEFORE anti TNF Rx or any other biologic therapy
- In paediatrics -If at baseline a negative test is recorded, then we advise retest every 12 months, as this tests for exposure.
- In adults no data is available re retest.
CXR – The main role is to exclude active disease.
- No cross reactivity in previously BCG Vaccinated patients
- QFT results may be confirmed with TST
- Must be conducted simultaneously to, or prior to TST
- Although QFT is not recommended for confirmation of TST results, QFT can be used for surveillance <12 months after a negative TST, if the initial QFT is negative
- Not indicated where active TB is suspected
Treatment choice for latency:
(b) INH alone – protected for 1 year in HIV patients.
- CDC guidelines – Advise INH at least 6 months minimum 9 months desirable.
- Combination Rifampicin – INH for 3 months, is advised in certain circumstances only. This applies where early initiation of therapy considered absolutely vital i.e. with aggressive disease.
(c) Duration of treatment.
- See clause (a) and (b).
(d) Time to start anti-TNF after latency treatment started
- Information limited. No data available
- recommend full treatment but practitioner judgement allowed vs. activity of disease
- INH – RIF regimen may be more useful here as shorter regimen.
(e) Monitoring of prophylaxis treatment.
- Concerns regarding treatment of latent status
- Hepatotoxicity – more significant in methotrexate co therapy.
(i) Liver function testing
1. ALT at baseline. Minimum testing – MONTHLY if baseline abnormal. 1% of INH patients will get increase in enzymes. Monitor Levels of ALTa. If >3 x with symptoms – stop
b. If > 5 times without symptoms – stop.
2. Education of patient regarding symptoms to suggest toxicity – i.e. nausea, vomiting, upper quadrant pain, dark urine..etc.
- Drug resistance – not considered a problem if TB Rx becomes required.
Repetition of screening program
(a) There is no evidence in adults of benefit to rescreening the MANTOUX -.
ii) To determine if active TB is present
(b) Diagnosis of active disease:
- CXR: If abnormal.
- Symptoms: Cough > 2 weeks
- Sputa if obtainable – plus culture (4 weeks.)
iii) Treatment in disease whilst on TNF.
(a) Diagnosis and Treatment in Patients with TNF drug Rx in situ.
- Beware of atypical disease / presentation.
- Extra pulmonary.
- Unusual histology – poor granuloma formation.
- STOP TNF drug.
- No reintroduction until TB therapy completed.
3) Ongoing vigilance in all patients on therapy is required at all times- even if MANTOUX negative