Potential cost-effectiveness of rifampin vs. isoniazid for latent tuberculosis: implications for future clinical trials

Review article: latent tuberculosis in patients with inflammatory bowel diseases receiving immunosuppression-risks, screening, diagnosis and management

BACKGROUND

One quarter of the world's population has latent tuberculosis infection (LTBI). Systemic immunosuppression is a risk factor for LTBI reactivation and the development of active tuberculosis. Such reactivation carries a risk of significant morbidity and mortality. Despite the increasing global incidence of inflammatory bowel disease (IBD) and the use of immune-based therapies, current guidelines on the testing and treatment of LTBI in patients with IBD are haphazard with a paucity of evidence.

AIM

To review the screening, diagnostic practices and medical management of LTBI in patients with IBD.

METHODS

Published literature was reviewed, and recommendations for testing and treatment were synthesised by experts in both infectious diseases and IBD.

RESULTS

Screening for LTBI should be performed proactively and includes assessment of risk factors, an interferon-gamma releasing assay or tuberculin skin test and chest X-ray. LTBI treatment in patients with IBD is scenario-dependent, related to geographical endemicity, travel and other factors. Ideally, LTBI therapy should be used prior to immune suppression but can be applied concurrently where urgent IBD medical treatment is required. Management is best directed by a multidisciplinary team involving gastroenterologists, infectious diseases specialists and pharmacists. Ongoing surveillance is recommended during therapy. Newer LTBI therapies show promise, but medication interactions need to be considered. There are major gaps in evidence, particularly with specific newer therapeutic approaches to IBD.

CONCLUSIONS

Proactive screening for LTBI is essential in patients with IBD undergoing immune-suppressing therapy and several therapeutic strategies are available. Reporting of real-world experience is essential to refining current management recommendations.

Using a quality improvement approach to improve care for latent tuberculosis infection

INTRODUCTION

Latent tuberculosis infection (LTBI) management is recognized as a key component of the World Health Organization End Tuberculosis Strategy. The term 'cascade of care in LTBI' has recently been used to refer to the process of LTBI management from identification of persons who may have LTBI to completion of treatment. Large gaps throughout the LTBI cascade of care have been identified. Areas covered: We have reviewed quality improvement (QI) as a potential approach for systematically improving gaps within the LTBI cascade of care. QI principles and approaches were reviewed, as well as the determinants of losses and evidence for solutions (interventions) within the LTBI cascade of care. An example of QI application in LTBI management is described. Expert commentary: Improving LTBI care at the magnitude required to reach the End TB Strategy goals will require systematic and context specific improvements at all steps in the cascade of care in LTBI. A continuous QI approach based on systems thinking, use of locally gathered data, and an iterative learning process can facilitate the process required to make the necessary improvements.

Burden of non-adherence to latent tuberculosis infection drug therapy and the potential cost-effectiveness of adherence interventions in Canada: a simulation study

OBJECTIVE

Pharmaceutical treatment of latent tuberculosis infection (LTBI) reduces the risk of progression to active tuberculosis (TB); however, poor adherence tempers the protective effect. We aimed to estimate the health burden of non-adherence, the maximum allowable cost of hypothetical new adherence interventions to be cost-effective and the potential value of existing adherence interventions for patients with low-risk LTBI in Canada.

DESIGN

A microsimulation model of LTBI progression over 25 years.

SETTING

General practice in Canada.

PARTICIPANTS

Individuals with LTBI who are initiating drug therapy.

INTERVENTIONS

A hypothetical intervention with a range of effectiveness was evaluated. Existing drug adherence interventions including peer support, two-way text messaging support, enhanced adherence counselling and adherence incentives were also evaluated.

PRIMARY AND SECONDARY OUTCOME MEASURES

Simulation outcomes included healthcare costs, TB incidence, TB deaths and quality-adjusted life years (QALYs). Base case results were interpreted against a willingness-to-pay threshold of $C50 000/QALY.

RESULTS

Compared with current adherence levels, full adherence to LTBI drug therapy could reduce new TB cases from 90.3 cases per 100 000 person-years to 35.9 cases per 100 000 person-years and reduce TB-related deaths from 7.9 deaths per 100 000 person-years to 3.1 deaths per 100 000 person-years. An intervention that increases relative adherence by 40% would bring the population near full adherence to drug therapy and could have a maximum allowable annual cost of approximately $C450 per person to be cost-effective. Based on estimates of effect sizes and costs of existing adherence interventions, we found that they yielded between 900 and 2400 additional QALYs per million people, reduced TB deaths by 5%-25% and were likely to be cost-effective over 25 years.

CONCLUSION

Full adherence could reduce the number of future TB cases by nearly 60%, offsetting TB-related costs and health burden. Several existing interventions are could be cost-effective to help achieve this goal.

Cost-effectiveness of rifampin for 4 months and isoniazid for 6 months in the treatment of tuberculosis infection

OBJECTIVES

To assess the cost-effectiveness ratio of rifampin for 4 months and isoniazid for 6 months in contacts with latent tuberculosis infection.

METHODS

The cost was the sum of the cost of treatment with isoniazid for 6 months or with rifampin for 4 months of all contacts plus the cost of treatment of cases of tuberculosis not avoided. The effectiveness was the number of cases of tuberculosis avoided with isoniazid for 6 months or with rifampin for 4 months. When the cost with one schedule was found to be cheaper than the other and a greater number of tuberculosis cases were avoided, this schedule was considered dominant. The efficacy adopted was 90% for rifampin for 4 months and 69% for isoniazid for 6 months. A sensitivity analysis was made for efficacies of rifampin for 4 months of 80%, 69%, 60% and 50%.

RESULTS

Of the 1002 patients studied, 863 were treated with isoniazid for 6 months and 139 with rifampin for 4 months The cost-effectiveness ratio with isoniazid for 6 month was € 19759.48/avoided case of tuberculosis and € 8736.86/avoided case of tuberculosis with rifampin for 4 months. Rifampin for 4 months was dominant. In the sensitivity analysis, rifampin for 4 months was dominant for efficacies from 60%.

CONCLUSIONS

Rifampin for 4 months was more cost-effective than isoniazid for 6 months.

Cost-effectiveness of rifampin for 4 months and isoniazid for 9 months in the treatment of tuberculosis infection

The purpose of this study was to evaluate the cost-effectiveness of the strategy of controlling the contacts of tuberculosis patients with latent tuberculosis infection by means of treatment with rifampin for 4 months or isoniazid for 9 months. The cost was the sum of the cost of treating latent tuberculosis infection in all contacts plus the cost of treating tuberculosis in whom the disease was not avoided. The effectiveness was expressed as cases avoided. The efficacy adopted was 90 % for rifampin for 4 months and 93 % for isoniazid for 9 months. We carried out a sensitivity analysis for efficacies of rifampin for 4 months of 80 %, 75 %, 69 % and 65 %. Of the 1,002 patients studied, 139 were treated with rifampin for 4 months and 863 were treated with isoniazid for 9 months. The cost-effectiveness was <euro>436,842.83/50 cases avoided with rifampin for 4 months and <euro>692,164.42/40 cases avoided with isoniazid for 9 months. Rifampin for 4 months was dominant. In the sensitivity analysis, rifampin for 4 months was dominant for efficacies of 75 % or greater. The cost-effectiveness analysis favoured the use of rifampin for 4 months when its efficacy was 75 % or greater.