Evaluating newly approved drugs in combination regimens for multidrug-resistant tuberculosis with fluoroquinolone resistance (endTB-Q): study protocol for a multi-country randomized controlled trial

BACKGROUND

Treatment for fluoroquinolone-resistant multidrug-resistant/rifampicin-resistant tuberculosis (pre-XDR TB) often lasts longer than treatment for less resistant strains, yields worse efficacy results, and causes substantial toxicity. The newer anti-tuberculosis drugs, bedaquiline and delamanid, and repurposed drugs clofazimine and linezolid, show great promise for combination in shorter, less-toxic, and effective regimens. To date, there has been no randomized, internally and concurrently controlled trial of a shorter, all-oral regimen comprising these newer and repurposed drugs sufficiently powered to produce results for pre-XDR TB patients.

METHODS

endTB-Q is a phase III, multi-country, randomized, controlled, parallel, open-label clinical trial evaluating the efficacy and safety of a treatment strategy for patients with pre-XDR TB. Study participants are randomized 2:1 to experimental or control arms, respectively. The experimental arm contains bedaquiline, linezolid, clofazimine, and delamanid. The control comprises the contemporaneous WHO standard of care for pre-XDR TB. Experimental arm duration is determined by a composite of smear microscopy and chest radiographic imaging at baseline and re-evaluated at 6 months using sputum culture results: participants with less extensive disease receive 6 months and participants with more extensive disease receive 9 months of treatment. Randomization is stratified by country and by participant extent-of-TB-disease phenotype defined according to screening/baseline characteristics. Study participation lasts up to 104 weeks post randomization. The primary objective is to assess whether the efficacy of experimental regimens at 73 weeks is non-inferior to that of the control. A sample size of 324 participants across 2 arms affords at least 80% power to show the non-inferiority, with a one-sided alpha of 0.025 and a non-inferiority margin of 12%, against the control in both modified intention-to-treat and per-protocol populations.

DISCUSSION

This internally controlled study of shortened treatment for pre-XDR TB will provide urgently needed data and evidence for clinical and policy decision-making around the treatment of pre-XDR TB with a four-drug, all-oral, shortened regimen.

TRIAL REGISTRATION

ClinicalTrials.Gov NCT03896685. Registered on 1 April 2018; the record was last updated for study protocol version 4.3 on 17 March 2023.

Outcomes of WHO-conforming, longer, all-oral multidrug-resistant TB regimens and analysis implications

BACKGROUND: Evidence of the effectiveness of the WHO-recommended design of longer individualized regimens for multidrug- or rifampicin-resistant TB (MDR/RR-TB) is limited.OBJECTIVES: To report end-of-treatment outcomes for MDR/RR-TB patients from a 2015-2018 multi-country cohort that received a regimen consistent with current 2022 WHO updated recommendations and describe the complexities of comparing regimens.METHODS: We analyzed a subset of participants from the endTB Observational Study who initiated a longer MDR/RR-TB regimen that was consistent with subsequent 2022 WHO guidance on regimen design for longer treatments. We excluded individuals who received an injectable agent or who received fewer than four likely effective drugs.RESULTS: Of the 759 participants analyzed, 607 (80.0%, 95% CI 77.0-82.7) experienced successful end-of-treatment outcomes. The frequency of success was high across groups, whether stratified on number of Group A drugs or fluoroquinolone resistance, and ranged from 72.1% to 90.0%. Regimens were highly variable regarding composition and the duration of individual drugs.CONCLUSIONS: Longer, all-oral, individualized regimens that were consistent with 2022 WHO guidance on regimen design had high frequencies of treatment success. Heterogeneous regimen compositions and drug durations precluded meaningful comparisons. Future research should examine which combinations of drugs maximize safety/tolerability and effectiveness.

Concordance of three approaches for operationalizing outcome definitions for multidrug-resistant TB

BACKGROUND: The WHO provides standardized outcome definitions for rifampicin-resistant (RR) and multidrug-resistant (MDR) TB. However, operationalizing these definitions can be challenging in some clinical settings, and incorrect classification may generate bias in reporting and research. Outcomes calculated by algorithms can increase standardization and be adapted to suit the research question. We evaluated concordance between clinician-assigned treatment outcomes and outcomes calculated based on one of two standardized algorithms, one which identified failure at its earliest possible recurrence (i.e., failure-dominant algorithm), and one which calculated the outcome based on culture results at the end of treatment, regardless of early occurrence of failure (i.e., success-dominant algorithm).METHODS: Among 2,525 patients enrolled in the multi-country endTB observational study, we calculated the frequencies of concordance using cross-tabulations of clinician-assigned and algorithm-assigned outcomes. We summarized the common discrepancies.RESULTS: Treatment success calculated by algorithms had high concordance with treatment success assigned by clinicians (95.8 and 97.7% for failure-dominant and success-dominant algorithms, respectively). The frequency and pattern of the most common discrepancies varied by country.CONCLUSION: High concordance was found between clinician-assigned and algorithm-assigned outcomes. Heterogeneity in discrepancies across settings suggests that using algorithms to calculate outcomes may minimize bias.

Using digital chatbots to close gaps in healthcare access during the COVID-19 pandemic

INTRODUCTION

Chatbots have emerged as a first link to care in recent years. The COVID-19 pandemic, and consequent health system disruptions, expanded their use. Socios En Salud (SES) introduced chatbots in Peru, which experienced one of the highest excess COVID mortalities in the world.

METHODS

SES and the government identified unmet population health needs, which could be amenable to virtual interventions. Chatbots were developed to screen individuals for these conditions; we describe the period of deployment, number of screenings, and number of people who received services.

RESULTS

Between April 2020 and May 2021, SES deployed nine ChatBots: four for mental health, two for maternal and child health, and three for chronic diseases: breast cancer, hypertension, diabetes mellitus, and obesity. Mental health services were provided to 42,932 people, 99.99% of those offered services. The other ChatBots reached fewer people. Overall, more than 50% of eligible people accepted chatbot-based services.

DISCUSSION

ChatBot use was highest for mental health. Chatbots may increase connections between a vulnerable population and health services; this is likely dependent on several factors, including condition, population, and penetration of smart phones. Future research will be critical to understand user experience and preferences and to ensure that chatbots link vulnerable populations to appropriate, high-quality care.

Factors associated with screening failure and study withdrawal in multidrug-resistant TB

SETTING: Multidrug-resistant TB (MDR-TB) clinical trial in Lima, Peru and Cape Town, South Africa.OBJECTIVE: To identify baseline factors associated with screening failure and study withdrawal in an MDR-TB clinical trial.DESIGN: We screened patients for a randomized, blinded, Phase II trial which assessed culture conversion over the first 6 months of treatment with varying doses of levofloxacin plus an optimized background regimen (ClinicalTrials.gov: NCT01918397). We identified factors for screening failure and study withdrawal using Poisson regression to calculate prevalence ratios and Cox proportional hazard regression to calculate hazard ratios. We adjusted for factors with P < 0.2.RESULTS: Of the 255 patients screened, 144 (56.5%) failed screening. The most common reason for screening failure was an unsuitable resistance profile on sputum-based molecular susceptibility testing (n = 105, 72.9%). No significant baseline predictors of screening failure were identified in the multivariable model. Of the 111 who were enrolled, 33 (30%) failed to complete treatment, mostly for non-adherence and consent withdrawal. No baseline factors predicted study withdrawal in the multivariable model.CONCLUSION: No baseline factors were independently associated with either screening failure or study withdrawal in this secondary analysis of a MDR-TB clinical trial.

Evaluating newly approved drugs for multidrug-resistant tuberculosis (endTB): study protocol for an adaptive, multi-country randomized controlled trial

BACKGROUND

Treatment of multidrug- and rifampin-resistant tuberculosis (MDR/RR-TB) is expensive, labour-intensive, and associated with substantial adverse events and poor outcomes. While most MDR/RR-TB patients do not receive treatment, many who do are treated for 18 months or more. A shorter all-oral regimen is currently recommended for only a sub-set of MDR/RR-TB. Its use is only conditionally recommended because of very low-quality evidence underpinning the recommendation. Novel combinations of newer and repurposed drugs bring hope in the fight against MDR/RR-TB, but their use has not been optimized in all-oral, shorter regimens. This has greatly limited their impact on the burden of disease. There is, therefore, dire need for high-quality evidence on the performance of new, shortened, injectable-sparing regimens for MDR-TB which can be adapted to individual patients and different settings.

METHODS

endTB is a phase III, pragmatic, multi-country, adaptive, randomized, controlled, parallel, open-label clinical trial evaluating the efficacy and safety of shorter treatment regimens containing new drugs for patients with fluoroquinolone-susceptible, rifampin-resistant tuberculosis. Study participants are randomized to either the control arm, based on the current standard of care for MDR/RR-TB, or to one of five 39-week multi-drug regimens containing newly approved and repurposed drugs. Study participation in all arms lasts at least 73 and up to 104 weeks post-randomization. Randomization is response-adapted using interim Bayesian analysis of efficacy endpoints. The primary objective is to assess whether the efficacy of experimental regimens at 73 weeks is non-inferior to that of the control. A sample size of 750 patients across 6 arms affords at least 80% power to detect the non-inferiority of at least 1 (and up to 3) experimental regimens, with a one-sided alpha of 0.025 and a non-inferiority margin of 12%, against the control in both modified intention-to-treat and per protocol populations.

DISCUSSION

The lack of a safe and effective regimen that can be used in all patients is a major obstacle to delivering appropriate treatment to all patients with active MDR/RR-TB. Identifying multiple shorter, safe, and effective regimens has the potential to greatly reduce the burden of this deadly disease worldwide.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02754765. Registered on 28 April 2016; the record was last updated for study protocol version 3.3, on 27 August 2019.

The fourth national anti-tuberculosis drug resistance survey in Peru

BACKGROUND: Peru has one of the highest burdens of multidrug-resistant tuberculosis (MDR-TB), but universal drug susceptibility testing (DST) has not yet been achieved.OBJECTIVE: To estimate the proportion of drug resistance among smear-positive TB patients in Peru.DESIGN: From September 2014 to March 2015, we performed a national drug resistance survey of patients aged ≥15 years; TB was diagnosed based on sputum smear positivity. We performed DST at the National Reference Laboratory of the Peruvian National Institute of Health, Lima, Peru, using the proportion method in Middlebrook 7H10 agar for four first-line drugs and six second-line drugs, and the Wayne method for pyrazinamide.RESULTS: Of the 1908 new and 272 previously treated patients included in the analysis, 638 (29.3%) patients had resistance to at least one first-line drug. MDR-TB was diagnosed in 7.3% of new and 16.2% of previously treated patients (P < 0.001). There were five (0.2%) patients with extensively drug-resistant TB.CONCLUSION: MDR-TB has increased to 7.3% in new patients from 5.3% in the previous survey, indicating that resistance to anti-tuberculosis drugs is increasing in Peru. Ongoing community transmission of resistant strains highlights an urgent need for early diagnosis, optimised treatment and effective contact tracing of MDR-TB patients.

Time for a change: considering regimen changes in analyses of observational drug-resistant TB treatment cohort data

Randomized clinical trials represent the gold standard in therapeutic research. Nevertheless, observational cohorts of patients treated for multidrug-resistant TB (MDR-TB) or rifampin-resistant TB (RR-TB) also play an important role in generating evidence to guide drug-resistant TB care. Generally, summary exposure classifications (e.g., 'ever vs. never´, 'exposed at baseline´) have been used to characterize drug exposure in the absence of detailed longitudinal data on MDR-TB regimen changes. These summary classifications, along with an absence of data on covariates that change throughout the course of treatment, constrain researchers´ ability to answer the most relevant questions while accounting for known biases. In this paper, we highlight the importance of regimen changes in improving inference from observational studies of longer MDR-TB treatment regimens, and offer an overview of the data and analytic strategies required to do so.

Introducing new and repurposed TB drugs: the endTB experience

In 2015, the initiative Expand New Drug Markets for TB (endTB) began, with the objective of reducing barriers to access to the new and repurposed TB drugs. Here we describe the major implementation challenges encountered in 17 endTB countries. We provide insights on how national TB programmes and other stakeholders can scale-up the programmatic use of new and repurposed TB drugs, while building scientific evidence about their safety and efficacy. For any new drug or diagnostic, multiple market barriers can slow the pace of scale-up. During 2015-2019, endTB was successful in increasing the number of patients receiving new and repurposed TB drugs in 17 countries. The endTB experience has many lessons, which are relevant to country level introduction of new TB drugs, as well as non-TB drugs and diagnostics. For example: the importation of TB drugs is possible even in the absence of registration; emphasis on good clinical monitoring is more important than pharmacovigilance reporting; national guidelines and expert committees can both facilitate and hinder innovative practice; clinicians use new and repurposed TB drugs when they are available; data collection to generate scientific evidence requires financial and human resources; pilot projects can drive national scale-up.

Feasibility and yield of screening for non-communicable diseases among treated tuberculosis patients in Peru

INTRODUCTION

The increasing prevalence of non-communicable diseases (NCDs) poses a major challenge to low- and middle-income countries. Patients' engagement with health services for anti-tuberculosis treatment provides an opportunity for screening for NCDs and for linkage to care.

METHODS

We explored the feasibility and yield of screening for NCDs in patients treated for tuberculosis (TB) in Lima, Peru, as part of a study focused on chronic respiratory sequelae. A representative sample of community controls was recruited from the same geographical area. Screening entailed taking a medical history and performing ambulatory blood pressure measurement and urinalysis.

RESULTS

A total of 177 participants with previous TB (33 with multidrug-resistant TB) and 161 community controls were evaluated. There was an almost four-fold increased prevalence of self-reported diabetes mellitus (DM) in the TB group (adjusted prevalence ratio 3.66, 95%CI 1.68-8.01). Among those without self-reported DM, 3.3% had glycosuria, with a number needed to screen (NNS) of 31. The NNS to find one (new) case of hypertension or proteinuria in the TB group was respectively 24 and 5.

CONCLUSION

Patient-centred care that includes pragmatic NCD screening is feasible in TB patients, and the treatment period provides a good opportunity to link patients to ongoing care.

Prevalence of pyrazinamide resistance and Wayne assay performance analysis in a tuberculosis cohort in Lima, Peru

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) regimens often contain pyrazinamide (PZA) even if susceptibility to the drug has not been confirmed. This gap is due to the limited availability and reliability of PZA susceptibility testing.

OBJECTIVES

To estimate the prevalence of PZA resistance using the Wayne assay among TB patients in Lima, Peru, to describe characteristics associated with PZA resistance and to compare the performance of Wayne with that of BACTEC™ MGIT™ 960.

METHODS

PZA susceptibility using the Wayne assay was tested in patients diagnosed with culture-positive pulmonary TB from September 2009 to August 2012. Factors associated with PZA resistance were evaluated. We compared the performance of the Wayne assay to that of MGIT 960 in a convenience sample.

RESULTS

The prevalence of PZA resistance was 6.6% (95%CI 5.8-7.5) among 3277 patients, and 47.7% (95%CI 42.7-52.6) among a subset of 405 MDR-TB patients. In multivariable analysis, MDR-TB (OR 86.0, 95%CI 54.0-136.9) and Latin American-Mediterranean lineage (OR 3.40, 95%CI 2.33-4.96) were associated with PZA resistance. The Wayne assay was in agreement with MGIT 960 in 83.9% of samples (κ 0.66, 95%CI 0.56-0.76).

CONCLUSION

PZA resistance was detected using the Wayne assay in nearly half of MDR-TB patients in Lima. This test can inform the selection and composition of regimens, especially those dependent on additional resistance.

Estimating the global burden of multidrug-resistant tuberculosis among prevalent cases of tuberculosis

BACKGROUND

Estimates of the multidrug-resistant tuberculosis (MDR-TB) burden are based on incomplete, infrequently updated data among a limited pool of notified or incident pulmonary TB cases.

METHODS

Using World Health Organization data reported by 217 countries/territories in 2014, we calculated the MDR-TB burden among prevalent TB cases and compared these with estimates among incident and notified TB patients. We also compared treatment coverage across estimates.

RESULTS

Among prevalent TB patients worldwide in 2014, we estimate that 555 545 (95% credible bounds 499 340-617 391) MDR-TB cases occurred. This is 85% more than the 300 000 estimated among notified cases, and 16% more than the 480 000 among incident cases. Only 20% of MDR-TB cases among prevalent-compared to 37% of MDR-TB among notified-TB patients had access to MDR-TB treatment. Applying prior estimates, only 10% of MDR-TB cases will have successful outcomes.

CONCLUSION

Estimates based on likely-to-be-diagnosed cases of MDR-TB overlook a significant proportion of morbidity, mortality, and transmission that occur in undiagnosed, untreated, prevalent TB patients. Even though it may still likely underestimate the true disease burden, MDR-TB among patients with prevalent TB represents a closer approximation of disease burden than currently reported indicators. Progress toward elimination or control depends on policies guided by a more complete representation of the disease burden.

Drug-resistant tuberculosis clinical trials: proposed core research definitions in adults

Drug-resistant tuberculosis (DR-TB) is a growing public health problem, and for the first time in decades, new drugs for the treatment of this disease have been developed. These new drugs have prompted strengthened efforts in DR-TB clinical trials research, and there are now multiple ongoing and planned DR-TB clinical trials. To facilitate comparability and maximise policy impact, a common set of core research definitions is needed, and this paper presents a core set of efficacy and safety definitions as well as other important considerations in DR-TB clinical trials work. To elaborate these definitions, a search of clinical trials registries, published manuscripts and conference proceedings was undertaken to identify groups conducting trials of new regimens for the treatment of DR-TB. Individuals from these groups developed the core set of definitions presented here. Further work is needed to validate and assess the utility of these definitions but they represent an important first step to ensure there is comparability in clinical trials on multidrug-resistant TB.

Presumptive treatment of multidrug-resistant tuberculosis in household contacts

SETTING

Multidrug-resistant tuberculosis (MDR-TB) is a growing global health threat that often requires presumptive treatment in the absence of drug susceptibility testing (DST) results.

OBJECTIVE

To compare two approaches to the treatment of MDR-TB contacts with no DST results who develop TB disease.

DESIGN

We conducted a retrospective cohort study of adults treated for TB disease who were contacts of patients living with MDR-TB. Subjects had been treated according to one of two presumptive treatment strategies: 1) regimens containing exclusively first-line drugs, and 2) regimens that included both first- and second-line drugs that were adjusted if and when DST results became available. The primary endpoint was a composite of death and treatment failure.

RESULTS

Household contacts of MDR-TB patients who developed TB disease and were treated with first-line regimens were significantly more likely to experience unfavorable end-of-treatment outcomes than those treated with presumptive MDR-TB regimens (RR 2.88, 95%CI 1.24-6.68).

CONCLUSION

Household contacts of MDR-TB patients who develop TB disease but have no DST results should receive regimens containing second-line drugs selected based on the infecting strain of the index patient. Regimens containing only first-line anti-tuberculosis drugs significantly increase the risk of unfavorable outcomes.

Salvage therapy for multidrug-resistant tuberculosis

Treatment of multidrug-resistant tuberculosis (MDR-TB), defined as Mycobacterium tuberculosis resistant to both isoniazid and rifampicin, is challenging under the best of circumstances, and particularly in resource-limited settings. For patients who remain persistently sputum-culture-positive despite therapy with second-line TB drugs, treatment options are limited, especially if disease is too advanced for resective surgery. Salvage therapy refers to the design of a regimen combining new and previously used drugs in a final effort to attain sputum conversion before declaring treatment to have failed. We retrospectively evaluated the outcomes of salvage therapy in 213 Peruvian patients. Salvage regimens included a median of two new drugs (range 1-6) and nine (range 5-13) total (new plus previously used) drugs. The most frequently used new drug was moxifloxacin, followed by capreomycin, amoxicillin-clavulanate, kanamycin and clarithromycin. Culture conversion occurred in 65 (30.5%) patients. Salvage regimens that included moxifloxacin were significantly more likely to be followed by culture conversion (OR 2.2; p 0.02). Later-generation fluoroquinolones such as moxifloxacin should be used in salvage therapy but also in the initial treatment of MDR-TB, if the best clinical strategy is to use the most effective drugs when the patient has the best chance for cure. New TB drugs are most likely to be initially used in salvage patients, in conditions similar to those described here. Close bacteriological monitoring of these patients will be essential, as useful information about the best way to use these new drugs can be gained from analysis of salvage therapy cohorts.

Predictors of sputum culture conversion among patients treated for multidrug-resistant tuberculosis

OBJECTIVE

To identify predictors of initial sputum culture conversion, estimate the usefulness of persistent positive cultures at different time points in predicting treatment failure, and evaluate different definitions of culture conversion for predicting failure among patients with multidrug-resistant tuberculosis (MDR-TB) in five countries, 2000-2004.

METHODS

Predictors of time to conversion were identified using multivariate Cox proportional hazards regression modeling. Receiver operating characteristic curves were plotted to visualize the effect of using different definitions of 'culture conversion' on the balance between sensitivity and specificity.

RESULTS

Overall, 1209/1416 (85%) of patients with baseline positive cultures converted in a median of 3.0 months (interquartile range 2.0-5.0). Independent predictors of less likely conversion included baseline positive smear (hazard ratio [HR] 0.60, 95%CI 0.53-0.68), resistance to pyrazinamide (HR 0.82, 95%CI 0.70-0.96), fluoroquinolones (FQs; HR 0.65, 95%CI 0.51-0.83) or thioamide (HR 0.83, 95%CI 0.71-0.96), previous use of FQs (HR 0.71, 95%CI 0.60-0.83), poor outcome of previous anti-tuberculosis treatment (HR 0.69, 95%CI 0.54-0.88) and alcoholism (HR 0.74, 95%CI 0.63-0.87). The maximum combined sensitivity (84%) and specificity (94%) in predicting treatment failure was based on lack of culture conversion at month 9 of treatment, assuming conversion is defined as five consecutive negative cultures.

CONCLUSION

Patients with identified risk factors were less likely to achieve sputum culture conversion during MDR-TB treatment.

Concordance of programmatic and laboratory-based multidrug-resistant tuberculosis treatment outcomes in Peru

BACKGROUND

Confirmation of cure for multidrug-resistant tuberculosis (MDR-TB) patients requires laboratory tests for Mycobacterium tuberculosis growth on culture media. Outcome decisions dictate patient management, and inaccuracies place patients at an increased risk of morbidity and mortality, and may contribute to continued transmission of MDR-TB.

OBJECTIVE

To examine concordance between programmatic and laboratory-based MDR-TB treatment outcomes.

METHODS

The study population included 1658 MDR-TB patients in Peru treated between 1996 and 2002 with both program and laboratory-based outcomes. Laboratory-based outcomes were assigned according to international standards requiring at least five consecutive negative cultures in the last 12 months of treatment to confirm cure.

RESULTS

Compared to the global culture-defined standard classification, only 1.1% of treatment successes, but 54.3% of failures, were misclassified programmatically. Overall, 10.4% of patients identified by a clinician as having a successful treatment outcome still had cultures positive for MDR-TB.

CONCLUSION

Most patients with successful treatment outcomes by strict culture definitions were also classified by clinicians as having successful outcomes. However, many culture-confirmed failures were missed. In light of delays and incomplete access to culture in MDR-TB programs, efforts should be made to improve the accuracy of programmatically determined treatment outcomes.

Bacteriologic monitoring of multidrug-resistant tuberculosis patients in five DOTS-Plus pilot projects

BACKGROUND

Multidrug-resistant tuberculosis programs in DOTS-Plus pilot sites in five countries.

OBJECTIVES

To calculate sputum conversion time and its relationship to treatment outcome, document the frequency of culture reversions and examine concordance of smear and culture to assess the potential consequences of monitoring by smear microscopy alone.

DESIGN

Retrospective cohort analysis of 1926 patients receiving individualized, second-line therapy.

RESULTS

Among 1385 sputum culture-positive cases at baseline, 1146 (83%) experienced at least one culture conversion during treatment. Conversion, however, was not sustained in all patients: 201 (15%) experienced initial culture conversion and at least one subsequent culture reversion to positive; 1064 (77%) achieved sustained culture conversion. Median time to culture conversion was 3 months. Among 206 patients whose nal conversion occurred 7-18 months after the initiation of therapy, 71% were cured or had completed treatment.

CONCLUSIONS

Prolonged treatment for patients with delayed conversion may be beneficial, as 71% of late converters still achieved cure or completed treatment. This has implications for programs with de ned end points for treatment failure. The interval between rst and nal conversion among patients whose initial con- version is not sustained raises concern with respect to the ongoing debate regarding duration of treatment and the definition of cure.

Frequency and type of microbiological monitoring of multidrug-resistant tuberculosis treatment

Monthly culture is usually recommended to monitor treatment of multidrug-resistant tuberculosis (MDR-TB). As mycobacterial laboratory capacity is limited in many settings, TB programs need evidence to decide whether monthly cultures are necessary compared to other approaches. We simulated three alternative monitoring strategies (culture every 2 or 3 months, and monthly smears alone) in a cohort of MDR-TB patients in Estonia, Latvia, Philippines, Russia and Peru from 2000 to 2004. This retrospective analysis illustrated that less frequent testing delays confirmation of bacteriological conversion. This would prolong intensive treatment, hospitalization and respiratory isolation, increasing cost and toxicity. After conversion, less frequent testing could delay diagnosis of possible treatment failure.

WHO guidelines for the programmatic management of drug-resistant tuberculosis: 2011 update

The production of guidelines for the management of drug-resistant tuberculosis (TB) fits the mandate of the World Health Organization (WHO) to support countries in the reinforcement of patient care. WHO commissioned external reviews to summarise evidence on priority questions regarding case-finding, treatment regimens for multidrug-resistant TB (MDR-TB), monitoring the response to MDR-TB treatment, and models of care. A multidisciplinary expert panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to develop recommendations. The recommendations support the wider use of rapid drug susceptibility testing for isoniazid and rifampicin or rifampicin alone using molecular techniques. Monitoring by sputum culture is important for early detection of failure during treatment. Regimens lasting ≥ 20 months and containing pyrazinamide, a fluoroquinolone, a second-line injectable drug, ethionamide (or prothionamide), and either cycloserine or p-aminosalicylic acid are recommended. The guidelines promote the early use of antiretroviral agents for TB patients with HIV on second-line drug regimens. Systems that primarily employ ambulatory models of care are recommended over others based mainly on hospitalisation. Scientific and medical associations should promote the recommendations among practitioners and public health decision makers involved in MDR-TB care. Controlled trials are needed to improve the quality of existing evidence, particularly on the optimal composition and duration of MDR-TB treatment regimens.

Representative drug susceptibility patterns for guiding design of retreatment regimens for MDR-TB

BACKGROUND

There is no gold standard on how national tuberculosis programs should design retreatment regimens. Often drug susceptibility testing (DST) is not available for all patients, and representative DST patterns in patient populations are used to guide therapy.

OBJECTIVES

To examine DST patterns in different patient populations based on previous treatment and to estimate the number of effective anti-tuberculosis agents in several retreatment regimens.

METHODS

We reviewed DST results from patients treated with individualized regimens in Peru between January 1998 and July 2004. We stratified patients into four groups based on previous treatment exposure from Group 1 who had failed only one regimen to Group 4 who had failed three regimens. We compared resistance frequencies across the four groups. In Groups 1 and 3, the number of likely effective agents under six possible retreatment regimen scenarios was estimated.

RESULTS

Resistance to second-line drugs was significantly higher in groups with more previous courses of treatment. A few retreatment regimens could be identified that would allow at least 80% of patients to receive at least four likely effective drugs.

CONCLUSION

Because it is associated with resistance frequencies, previous treatment exposure can serve to guide the design of non-individualized MDR-TB regimens.

Speaking the same language: treatment outcome definitions for multidrug-resistant tuberculosis

SETTING

Globally it is estimated that 273000 new cases of multidrug-resistant tuberculosis (MDR-TB, resistance to isoniazid and rifampicin) occurred in 2000. To address MDR-TB management in the context of the DOTS strategy, the World Health Organization and partners have been promoting an expanded treatment strategy called DOTS-Plus. However, standard definitions for MDR-TB patient registration and treatment outcomes do not exist.

OBJECTIVE

To propose a standardized set of case registration groups and treatment outcome definitions for MDR-TB and procedures for conducting cohort analyses under the DOTS-Plus strategy.

DESIGN

Using published definitions for drug-susceptible TB as a guide, a 2-year-long series of meetings, conferences, and correspondence was undertaken to review published literature and country-specific program experience, and to develop international agreement.

RESULTS

Definitions were designed for MDR-TB patient categorization, smear and culture conversion, and treatment outcomes (cure, treatment completion, death, default, failure, transfer out). Standards for conducting outcome analyses were developed to ensure comparability between programs.

CONCLUSION

Optimal management strategies for MDR-TB have not been evaluated in controlled clinical trials. Standardized definitions and cohort analyses will facilitate assessment and comparison of program performance. These data will contribute to the evidence base to inform decision makers on approaches to MDR-TB control.

Self-administered, standardized regimens for multidrug-resistant tuberculosis in South Korea

SETTING

National Masan Tuberculosis Hospital, Masan, South Korea, a 430-bed tertiary referral hospital specializing in tuberculosis.

OBJECTIVE

To evaluate the treatment outcomes of standardized, empiric regimens for multidrug-resistant tuberculosis (MDR-TB).

DESIGN

A retrospective analysis of the hospital records of 142 patients with MDR-TB who had failed short-course chemotherapy. Between 1 January 1998 and 30 June 2000, patients were started on one of two standardized, empiric regimens based on previous treatment history. Drug susceptibility testing of the infecting strain was not used to modify the treatment regimen. Treatment was continued for at least 18 months after conversion to a negative culture.

RESULTS

Sixty-three patients (44.1%) were cured and discharged from treatment after at least 18 months of negative cultures; 18 (12.7%) failed treatment, 41 (28.9%) defaulted, four died (2.8%), and 15 (10.6%) were transferred to another institution. One patient is still on treatment. Resistance to ofloxacin was the only risk factor related to poor outcome (death or failure) in univariate or multiple logistic regression analysis.

CONCLUSIONS

High levels of resistance to second-line drugs are likely a cause of poor outcome of MDR-TB therapy in Korea. Directly observed therapy and other methods to increase patient compliance should be considered nationwide, as they may improve MDR-TB treatment outcomes.

Identifying early treatment failure on category I therapy for pulmonary tuberculosis in Lima Ciudad, Peru

SETTING

Ambulatory, public tuberculosis treatment facilities, central Lima, Peru.

OBJECTIVE

To identify risk factors for failure on directly observed Category I therapy.

DESIGN

Case-control study. All failures of Category I (2HREZ/4H2R2) therapy in 2000 (2.9% of smear-positive TB patients) were included as cases; two controls per case were matched on health center and approximate time of treatment initiation.

RESULTS

The study included 38 cases and 76 controls, all new smear-positive, pulmonary TB patients treated with Category I therapy in central Lima in 2000. Neither treatment irregularity nor incidence of adverse events predicted failure in the study group. Mean baseline body mass index was lower in cases than in controls (P = 0.06). Cases gained less weight during therapy (P = 0.01). Smear positivity at 2 months of therapy was strongly associated with failure (OR 11.7; 95%CI 2.4-57.5). No controls had positive smears at or after 3 months of therapy (OR [corrected] 144.9; 95%CI 8.4-2500). Nearly 75% of cases with isolates tested for susceptibility to first-line drugs had multidrug-resistant TB (MDR-TB).

CONCLUSION

A large proportion of failures on Category I therapy can be identified early. As three-quarters of patients with susceptibility results have MDR-TB, early referral for culture and drug susceptibility testing is critical for prompt initiation of appropriate therapy and improved outcomes.

Peripheral neuropathy associated with treatment for multidrug-resistant tuberculosis

OBJECTIVE

To review the incidence and management of peripheral neuropathy in patients receiving therapy for MDR-TB.

METHODS

A case series with retrospective chart review of 75 patients who initiated individualized therapy for multidrug-resistant tuberculosis (MDR-TB) in Lima, Peru, between 1 August 1996 and 31 January 1999.

RESULTS

All patients had confirmed MDR-TB and were receiving individualized therapy, comprised of an average of six drugs. Ten (13%) of these patients presented with symptoms of peripheral neuropathy, confirmed by electromyography. All symptoms were reported in the lower extremities, and all were sensory in nature. Median time to presentation from initiation of MDR-TB therapy was 9.1 months. No significant risk factors associated with development of peripheral neuropathy were identified. Management strategies depended on the severity of symptoms and included the treatment of contributing co-morbidities, medications for neuropathic pain, and adjustment of doses of possible offending agents. All patients responded to management; three patients were left with mild residual symptoms. Patients whose neuropathy resolved had symptoms for a median of 7 months.

CONCLUSIONS

Peripheral neuropathy was encountered in 13% of our cohort of MDR-TB patients. The diagnosis of peripheral neuropathy can be based on clinical presentation alone, and effective management of this side-effect is possible without sacrificing MDR-TB treatment efficacy.

Occurrence of serious adverse effects in patients receiving community-based therapy for multidrug-resistant tuberculosis

SETTING

A community-based treatment program for multidrug-resistant tuberculosis (MDR-TB) in an urban shantytown of Lima, Peru.

OBJECTIVES

To ascertain the occurrence of serious adverse effects associated with therapy for MDR-TB in northern Lima, Peru, where therapy was individualized according to drug-susceptibility testing of patients' infecting strains and delivered through a community-based program.

DESIGN

A retrospective record review of 60 patients who had received individualized therapy for MDR-TB between September 1996 and October 1998.

RESULTS

Although adverse effects were common, they occurred less frequently than previously reported in the literature and were rarely life-threatening. Effects occurring most frequently in this population included: mild gastritis (100%), dermatological effects (43.3%), peripheral neuropathy (16.7%), depression (18.3%), and anxiety (11.7%). These effects never resulted in the discontinuation of anti-tuberculosis therapy, and only occasionally resulted in the suspension of an agent (11.7%).

CONCLUSION

In young patients with little comorbid disease, multidrug, long-course regimens rarely caused life-threatening adverse effects. Common side effects may be managed successfully on an out-patient basis through a community-based treatment program in conjunction with MDR-TB experts, even in resource-poor settings. The very low rate of default in this cohort offers hope that strategies to manage the adverse effects may reduce the incidence of abandonment of therapy and increase rates of cure.