Cost-effectiveness of a 12-dose regimen for treating latent tuberculous infection in the United States

Abstract

Setting: A large randomized controlled trial recently showed that for treating latent tuberculous infection (LTBI) in persons at high risk of progression to tuberculosis (TB) disease, a 12-dose regimen of weekly rifapentine plus isoniazid (3HP) administered as directly observed treatment (DOT) can be as effective as 9 months of daily self-administered isoniazid (9H).

Objectives: To assess the cost-effectiveness of 3HP compared to 9H.

Design: A computational model was designed to simulate individuals with LTBI treated with 9H or 3HP. Costs and health outcomes were estimated to determine the incremental costs per active TB case prevented and per quality-adjusted life year (QALY) gained by 3HP compared to 9H.

Results: Over a 20-year period, treatment of LTBI with 3HP rather than 9H resulted in 5.2 fewer cases of TB and 25 fewer lost QALYs per 1000 individuals treated. From the health system and societal perspectives, 3HP would cost respectively US$21,525 and $4294 more per TB case prevented, and respectively $4565 and $911 more per QALY gained.

Conclusions: 3HP may be a cost-effective alternative to 9H, particularly if the cost of rifapentine decreases, the effectiveness of 3HP can be maintained without DOT, and 3HP treatment is limited to those with a high risk of progression to TB disease.

Figures

Figure A.1

Distribution of ages of clinical trial participants at the time of enrollment in the clinical trial: mean: 36 years; median: 35 years; maximum: 103 years; minimum: 2 years. Data provided by the Tuberculosis Trials Consortium Data Coordinating Center.

Figure A.2

Health system perspective acceptability curve for the multivariate sensitivity analysis from Table A.11. Curve shows the fraction of sensitivity runs that were cost-effective from the health system perspective for each threshold value λ (the fraction of simulations for which the incremental cost per QALY gained by 3HP compared to 9H was ≤λ). Each run represents one of the 324 combinations of parameters from Table A.11 and was simulated using 50 000 individuals for each regimen. QALY = quality-adjusted life years; 3HP = 12-dose regimen of weekly rifapentine plus isoniazid; 9H = 9 months of daily, self-administered isoniazid.

Figure A.3

Societal perspective acceptability curve for the multivariate sensitivity analysis from Table A.11. Curve shows the fraction of sensitivity runs that were cost-effective from the societal perspective for each threshold value λ (the fraction of simulations for which the incremental cost per QALY gained by 3HP compared to 9H was ≤λ). Each run represents one of the 324 combinations of parameters from Table A.11 and was simulated using 50 000 individuals for each regimen. QALY = quality-adjusted life years; 3HP = 12-dose regimen of weekly rifapentine plus isoniazid; 9H = 9 months of daily, self-administered isoniazid.

Figure 1

Cost of a complete course of treatment for latent tuberculous infection with either 9H or 3HP administered by DOT from a health care worker. Patients receiving 9H have an initial clinic visit and eight later clinic visits; those receiving 3HP have an initial clinic visit, two later clinic visits and 12 visits by a health care worker for DOT. Patient costs include out-of-pocket expenses and lost productivity; other costs are costs to the health system. Costs are in 2010 US dollars. 3HP = 3 months of weekly isoniazid plus rifapentine; 9H = 9 months of daily, self-administered isoniazid; DOT = directly observed treatment.

Figure 2

Total costs per person treated for LTBI. Average costs are over a 20-year period for individuals treated for LTBI with either 9H or 3HP administered by DOT from a health care worker. Costs include those of LTBI treatment and the eventual development of tuberculosis disease in some individuals. Patient costs include out-of-pocket expenses and lost productivity; other costs are costs to the health system. Based on 100 000 simulated individuals per regimen with a 20-year analytic horizon; costs are reported in 2010 US dollars and have been discounted at an annual rate of 3%. LTBI = latent tuberculous infection; 3HP = 3 months of weekly isoniazid plus rifapentine; 9H = 9 months of daily, self-administered isoniazid; DOT = directly observed treatment.