Decisions regarding INH treatment for latent TB Infection (LTBI) are balanced between:
- 5% – 10% lifetime risk of Active TB
- Higher risk with certain co-morbidities
- Risk of INH-induced hepatitis (<0.4% at age 35; > 65 y.o. up to 4% risk)
In general, the younger the person, the less chance of hepatotoxicity, & the greater lifetime risk of active TB. But some older persons carry great risks of Active TB.
Current CDC Guidelines from 2001 are somewhat vague. Current interpretation of them — the following persons with LTBI should be treated:
1. Regardless of Age: persons with high risk of Active TB
• AIDS • HIV • Silicosis • Malnutrition • Renal Failure (dialysis) • Cancer: head & neck, lymphoma, leukemia • ChemoTx; TNF-Inhibitors; Organ Transplant Meds • CXR w/ “old scars” of prior healed TB • Infected (LTBI) within last 2 yrs (“conversion”)2. <65 y.o.: • Diabetes • Prednisone ≥15 mg/d for ≥1 mo
3. <50 y.o.: • Immigrants from high-prevalence countries in U.S. <5 yrs. • Smokers • Underweight persons w/ BMI <204. <35 y.o.: • Everyone with Positive PPD/IGRA (regardless of time in U.S.)
Treatment Options
1. INH 300 mg daily for 9 months (6 months acceptable)
2. INH 900 mg + Rifapentine 900 mg once weekly- by directly observed therapy, x12 wks
3. Rifampin 600 mg daily x4 mos [more side effects]
Caveats Rx 30 days at a time; have pt seen q mo to review Sx of drug-induced hepatitis:- malaise, anorexia, nausea, upper abdominal pain
- jaundice is pre-terminal (don’t emphasize this as Sx)
- In case of Sx lasting >2 d, pt must a) d/c INH; AND b) come to clinic ASAP for LFTs
- NOTE: purpose of review is so pt remembers danger signs during the following month
- incr. risk hepatitis earlier
- Begin INH any time if pt at high risk of active TB
- INH is not teratogenic [even in 1st trimester]
NEVER give INH for LTBI unless CXR normal (or work-up done for TB-4 [“old scar”; see posting TB-1 Intro]).
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