Clinical and economic impact of medication non-adherence in drug-susceptible tuberculosis: a systematic review.

BACKGROUND: Despite considerable efforts to globally eradicate TB, and the availability of effective antibiotics, TB elimination goals are falling behind. While non-adherence to TB drug regimens may compromise effective treatment, its full impact is still unknown.OBJECTIVE: To determine the clinical and economic impact of non-adherence to TB medication on treatment outcomes in drug-susceptible TB patients (DS-TB).METHODS: A systematic review was performed using PubMed and Embase for studies published between 2009 and 2019 reporting associations between adherence and WHO-defined TB treatment outcomes and economic outcomes in DS-TB patients.RESULTS: A total of 14 studies were included. Eight focused on the association between non-adherence and death, 2 on treatment failure, 1 study on successful treatment outcome, 1 study on both successful and unsuccessful treatment outcomes and 2 on cost outcomes. Most studies (71.4%) were retrospective cohort or case-control studies. The results showed that non-adherence to TB drug regimens was associated with death, treatment failure and lower cure rates.CONCLUSION: Non-adherence to TB drugs has a profound impact on both clinical and economic TB outcomes. To reach WHO TB elimination goals, preventing non-adherence and the implementation of cost-effective intervention programmes should receive the highest priority.

Cost-utility analysis of high-dose treatment for intermediate-susceptible, dose-dependent tuberculosis patients.

SETTING: We proposed to: 1) introduce an intermediate-susceptible, dose-dependent (ISDD) category for Mycobacterium tuberculosis infection; and 2) treat patients with M. tuberculosis infection in this category with a high dose of rifampicin (RMP) and isoniazid (INH). OBJECTIVE: To examine the impact of our strategy on quality-adjusted life-years (QALY) and costs in a low-income country with a high prevalence of multidrug-resistant tuberculosis (MDR-TB) (Belarus) and a high-income, low MDR-TB prevalence country (The Netherlands). DESIGN: A Markov model comprising 14 health states was used to simulate treatment outcomes and costs accrued over 5 years for a hypothetical cohort of 10 000 patients. One-way sensitivity analysis, probabilistic sensitivity analysis and a scenario analysis were also performed. RESULTS: Our strategy was shown to be cost-effective for Belarus, but not for the Netherlands. At a willingness-to-pay of 50 000 euros per QALY, the probability of our strategy being cost-effective was 50% for the Netherlands and 57% for Belarus. CONCLUSION: The study shows that our strategy could be cost-effective and more efficacious. However, more studies are needed on the outcomes of using higher doses of INH and RMP.

Pharmacokinetic Modeling and Limited Sampling Strategies Based on Healthy Volunteers for Monitoring of Ertapenem in Patients with Multidrug-Resistant Tuberculosis.

Ertapenem is a broad-spectrum carbapenem antibiotic whose activity against Mycobacterium tuberculosis is being explored. Carbapenems have antibacterial activity when the plasma concentration exceeds the MIC at least 40% of the time (40% TMIC). To assess the 40% TMIC in multidrug-resistant tuberculosis (MDR-TB) patients, a limited sampling strategy was developed using a population pharmacokinetic model based on data for healthy volunteers. A two-compartment population pharmacokinetic model was developed with data for 42 healthy volunteers using an iterative two-stage Bayesian method. External validation was performed by Bayesian fitting of the model developed with data for volunteers to the data for individual MDR-TB patients (in which the fitted values of the area under the concentration-time curve from 0 to 24 h [AUC0-24, fit values] were used) using the population model developed for volunteers as a prior. A Monte Carlo simulation (n = 1,000) was used to evaluate limited sampling strategies. Additionally, the 40% TMIC with the free fraction (f 40% TMIC) of ertapenem in MDR-TB patients was estimated with the population pharmacokinetic model. The population pharmacokinetic model that was developed was shown to overestimate the area under the concentration-time curve from 0 to 24 h (AUC0-24) in MDR-TB patients by 6.8% (range, -17.2 to 30.7%). The best-performing limited sampling strategy, which had a time restriction of 0 to 6 h, was found to be sampling at 1 and 5 h (r2 = 0.78, mean prediction error = -0.33%, root mean square error = 5.5%). Drug exposure was overestimated by a mean percentage of 4.2% (range, -15.2 to 23.6%). When a free fraction of 5% was considered and the MIC was set at 0.5 mg/liter, the minimum f 40% TMIC would have been exceeded in 9 out of 12 patients. A population pharmacokinetic model and limited sampling strategy, developed using data from healthy volunteers, were shown to be adequate to predict ertapenem exposure in MDR-TB patients.