Unit 5: IPT Isoniazid TB Preventive Therapy

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Unit 5 IPTIsoniazid TB Preventive Therapy

• Botswana National Tuberculosis Programme Manual
  Training for Medical Officers

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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

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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

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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
  co-infected with HIV
• IPT is meant to prevent progression of latent TB
  to active disease
• INH shown to decrease incidence of TB among HIV-
  infected persons by about 40
• The protection period ranges from lt1 year to 3
  years

Source BNTP Manual, 2007.
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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)

Sources HIV Medicine Association, et al., 2007
BNTP Manual, 2007.
BIASII, 2004
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IPT Effectiveness
South African Miners, 2003
IPT usage TB incidence
IPT (n338) 8.6/100 person years
No IPT (n221) 19.1/100 person years
Source Churchyard GJ, Fielding K, et al., Aurum
Health Research, 2003.
Overall 55 reduction in TB incidence
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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
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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

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Screening Questions

• Cough for 2-3 weeks
• Weight loss
• Night sweats
• Fever
• Malaise
• Shortness of breath
• Chest pain
• Haemoptysis

• Consider EPTB
• Lymphadenopathy
• Headache
• Abdominal pain or distension
• Swollen joints
• Backache

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TB Screening Tests in Patients with Advanced HIV
Disease
Mohammed A, et al. Int J Tuberc Lung Dis, 2004.
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Screening Algorithm for IPT
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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

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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

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Emergence of Resistance with Single Drug Therapy
of Active TB
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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

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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

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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