Unit 5: IPT
Isoniazid TB Preventive Therapy
Botswana National Tuberculosis Programme
Manual Training for Medical Officers
Objectives
At the end of this unit, participants will be able to:
• Describe the role of INH Preventive Therapy
(IPT) for HIV-infected persons with latent TB
infection
• Describe how to appropriately screen eligible
patients for IPT
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-2
IPT: Isoniazid Preventive Therapy
• Type of secondary prevention
• To prevent development of active TB in HIV
positive individuals in whom active TB has
been excluded
• 6-month course of INH
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-3
Rationale for IPT
• 10% lifetime risk of developing active TB if infected
with M. tuberculosis alone
• 5-10% annual risk of developing active TB if coinfected with HIV
• IPT is meant to prevent progression of latent TB to
active disease
• INH shown to decrease incidence of TB among HIVinfected persons by about 40%
• The protection period ranges from <1 year to 3 years*
Unit 5: IPT: Isoniazid TB Preventive Therapy
Source: BNTP Manual, 2007.
Slide 5-4
Rationale for IPT in Botswana
• HIV prevalence is 17.1% in general population*
• TB case rate increased ~ 3-fold in 1990s**
• 1989: 199 /100,000
• 2002: 623 /100,000
• ~80% of adult TB cases are HIV co-infected***
• Patients more likely to seek HIV testing if they would receive
health benefit such as IPT and ART (1999 KABP study in
Botswana)
Unit 5: IPT: Isoniazid TB Preventive Therapy
Sources: *HIV Medicine Association, et al., 2007
** BNTP Manual, 2007.
***BIASII, 2004
Slide 5-5
IPT Effectiveness
South African Miners, 2003
IPT usage
TB incidence
IPT (n=338)
8.6/100 person years
No IPT (n=221)
19.1/100 person years
Source: Churchyard GJ, Fielding K, et al., Aurum Health Research, 2003.
Overall 55% reduction in TB incidence
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-6
IPT Effectiveness Related to ART
TB Incidence in 11,026 HIV-infected patients in Brazil
No INH
Yes INH
No ART
4.01/100
person years
1.27/100
person years
Yes ART
1.90/100
person years
0.80/100
person years
Source: Golub JE, et al., Johns Hopkins University 2007.
76% reduction with both INH and ART when adjusted for age,
previous TB diagnosis and CD4 count at baseline
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-7
Assessment for IPT
• Medical and social history
• Previous exposure to TB
• Previous treatment for TB
• HIV positive
• TB Screening questions
• Physical examination
• Clinical evaluation of TB suspects
• Sputum smear for microscopy and other
investigations as indicated
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-8
Screening Questions
•
•
•
•
•
•
•
•
Cough for 2-3 weeks
Weight loss
Night sweats
Fever
Malaise
Shortness of breath
Chest pain
Haemoptysis
Unit 5: IPT: Isoniazid TB Preventive Therapy
Consider EPTB:
• Lymphadenopathy
• Headache
• Abdominal pain or
distension
• Swollen joints
• Backache
Slide 5-9
TB Screening Tests in
Patients with Advanced HIV Disease
Mohammed A, et al. Int J Tuberc Lung Dis, 2004.
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-10
Screening Algorithm for IPT
Signs / symptoms of PTB
YES
All
negative
CXR &
assessment
Sputum
microscopy x 3
for AFB
ONE
positive
TB likely
TB unlikely
Treat for
bacterial
infection
NO
Poor
response
Good
response
Unit 5: IPT: Isoniazid TB Preventive Therapy
TREAT FOR
TB
INITIATE IPT
Slide 5-11
IPT Drugs and Dosages
• Recommended daily dosage:
• INH:
• Adults: 5 mg/kg/day, 300 mg/day max
• Children: 10-20 mg/kg/day, 300 mg/day
max
• Pyridoxine (B6) co-administered:
• 25mg orally, daily
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-12
Preventing Isoniazid Resistant TB
• Constant & proper use of the algorithm for the
dx of PTB to prevent monotherapy
• Screening of patients at each visit
• Thorough investigation of those suspected of
having TB
• Ongoing counselling of patients to maintain
adherence
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-13
Emergence of Resistance with
Single Drug Therapy of Active TB
Log cfu
Start INH alone
8
7
6
5
4
3
2
1
0
INH-Sensitive
INH-Resistant
0
2
4
6
8
Unit 5: IPT: Isoniazid TB Preventive Therapy
10 12 14 16
Weeks of Therapy
18
20
22
24
Slide 5-14
Reasons to Stop IPT
• Patient misses 2 consecutive monthly
refill/monitoring appointments
• Develops INH intolerance (serious side effect)
• Becomes terminally ill
• Potentially stop if female patient becomes pregnant
• If less than 3 months of IPT, discontinue
• If more than 3 months of IPT, continue treatment
• Develop symptoms of active TB
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-15
Patient Education Point
• Ensure HIV positive patients understand the benefits
of IPT (55% reduction in TB disease)
• Reinforce information at each visit
• Assess adherence to therapy, as with TB treatment
• Patients should be taught to recognize signs &
symptoms of active TB
• Discuss side-effects and support patient by problem
solving ways to manage minor SEs
• Encourage questions
Unit 5: IPT: Isoniazid TB Preventive Therapy
Unit 5: Infection Control and Prevention of TB
Slide 5-16
Key Points
• It is important to appropriately screen for signs
& symptoms of TB in HIV positive individuals
before initiating IPT
• HIV positive individuals have a 5-10% chance
of developing active TB per year
• IPT can prevent TB disease in HIV positive
individuals
Unit 5: IPT: Isoniazid TB Preventive Therapy
Slide 5-17