Cost-effectiveness of isoniazid preventive therapy among HIV-infected patients clinicaly screened for latent TB infection in Dar es Salaam, Tanzania: A prospective cohort study
Abstract
Background
One of the reasons why
Isoniazid preventive therapy (IPT) for Tuberculosis (TB) is not
widely used in low income countries is concerns on cost of
excluding active TB. We analyzed the cost-effectiveness of IPT
provision in Tanzania having ruled out active TB by a
symptom-based screening tool.
Methods
Data on IPT
cost-effectiveness was prospectively collected from an
observational cohort study of 1283 HIV-infected patients on IPT
and 1281 controls; followed up for 24 months. The time horizon
for the analysis was 2 years. Number of TB cases prevented and
deaths averted were used for effectiveness. A micro costing
approach was used from a provider perspective. Cost was
estimated on the basis of clinical records, market price or
interviews with medical staff. We annualized the cost at a
discount of 3%. A univariate sensitivity analysis was done.
Results are presented in US$ at an average annual exchange rate
for the year 2012 which was Tanzania shillings 1562.4 for 1 US
$.
Results
The number of TB cases
prevented was 420/100,000 persons receiving IPT. The number of
deaths averted was 979/100,000 persons receiving IPT.
Incremental cost due to IPT provision was US$ 170,490. The
incremental cost effective ratio was US $ 405.93 per TB case
prevented and US $ 174.15 per death averted. These costs were
less than 3 times the 768 US $ Gross Domestic Product (GDP) per
capita for Tanzania in the year 2014, making IPT provision after
ruling out active TB by the symptom-based screening tool
cost-effective. The results were robust to changes in laboratory
and radiological tests but not to changes in recurrent,
personnel, medication and utility costs.
Conclusion
IPT should be given to
HIV-infected patients who screen negative to symptom-based TB
screening questionnaire. Its cost-effectiveness supports
government policy to integrate IPT to HIV/AIDS care and
treatment in the country, given the availability of budget and
the capacity of health facilities.
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Source:
BMC Public Health
