Safety and Efficacy of Rifampin or Isoniazid Among People With Mycobacterium tuberculosis Infection and Living With Human Immunodeficiency Virus or Other Health Conditions: Post Hoc Analysis of 2 Randomized Trials

High-dose, short-duration versus standard rifampicin for tuberculosis preventive treatment: a partially blinded, three-arm, non-inferiority, randomised, controlled trial

BACKGROUND

Tuberculosis preventive treatment (TPT) is a key component of tuberculosis elimination. To improve completion and reduce the burden for people and health systems, short, safe, and effective TPT regimens are needed. We aimed to compare safety and treatment completion of various doses and durations of rifampicin in people who were recommended to receive TPT.

METHODS

This partially blinded, parallel-arm, non-inferiority, randomised, controlled, phase 2b trial was done at seven university-affiliated clinics in Canada, Indonesia, and Viet Nam. Participants aged 10 years or older were included if they had an indication for TPT according to WHO guidelines for Indonesia and Viet Nam, or Canadian guidelines for Canadian sites, and a positive tuberculin skin test or interferon-γ release assay. Participants were randomly assigned (1:1:1) to receive oral rifampicin at 10 mg/kg once daily for 4 months (standard-dose group), 20 mg/kg daily for 2 months (20 mg/kg group), or 30 mg/kg daily for 2 months (30 mg/kg group). The randomisation sequence was computer generated with blocks of variable size (three, six, and nine) and stratified by country for Indonesia and Viet Nam, and by city within Canada. Participants and investigators were masked to dose in high-dose groups, but unmasked to duration in all groups. The two co-primary outcomes were safety (in the safety population, in which participants received at least one dose of the study drug) and treatment completion (in the modified intention-to-treat [mITT] population, excluding those ineligible after randomisation). Protocol-defined adverse events were defined as grade 3 or worse, or rash or allergy of any grade, judged by an independent and masked panel as possibly or probably related to the study. A margin of 4% was used to assess non-inferiority. This study is registered with ClinicalTrials.gov, NCT03988933 (active).

FINDINGS

Between Sept 1, 2019, and Sept 30, 2022, 1692 people were assessed for eligibility, 1376 were randomly assigned, and eight were excluded after randomisation. 1368 participants were included in the mITT population (454 in the standard group, 461 in the 20 mg/kg group, and 453 in the 30 mg/kg group). 589 (43%) participants were male and 779 (57%) were female. 372 (82%) in the standard-dose group, 329 (71%) in the 20 mg/kg group, and 293 (65%) in the 30 mg/kg group completed treatment. No participants in the standard-dose group, one (<1%) of 441 participants in the 20 mg/kg group, and four (1%) of 423 in the 30 mg/kg group developed grade 3 hepatotoxicity. Risk of protocol-defined adverse events was higher in the 30 mg/kg group than in the standard-dose group (adjusted risk difference 4·6% [95% CI 1·8 to 7·4]) or the 20 mg/kg group (5·1% [2·3 to 7·8]). There was no difference in the risk of adverse events between the 20 mg/kg and standard-dose groups (-0·5% [95% CI -2·4 to 1·5]; non-inferiority met). Completion was lower in the 20 mg/kg group (-7·8% [95% CI -13·6 to -2·0]) and the 30 mg/kg group (-15·4% [-21·4 to -9·4]) than in the standard-dose group.

INTERPRETATION

In this trial, 2 months of 30 mg/kg daily rifampicin had significantly worse safety and completion than 4 months of 10 mg/kg daily and 2 months of 20 mg/kg daily (the latter, a fully blinded comparison); we do not consider 30 mg/kg to be a good option for TPT. Rifampicin at 20 mg/kg daily for 2 months was as safe as standard treatment, but with lower completion. This difference remains unexplained.

FUNDING

Canadian Institutes of Health Research.

Diagnosis and Management of Latent Tuberculosis Infection: Updates

India has the largest problem of tuberculosis (TB) infection globally (estimated at about 35-40 crores cases), and around 18-36 lakh develop active tuberculosis annually. Latent TB is defined as a state of persistent immune response to stimulation by Mycobacterium tuberculosis antigens with no evidence of clinically manifested active TB. The progression of a latent infection to active tuberculosis increases several-fold in children < 5 years of age and in people with some or the other form of an immunocompromising condition. Therefore, to cater to this gigantic problem of tuberculosis, it is necessary to have awareness about latent tuberculosis infection (LTBI) amongst clinicians and to prioritise its diagnosis and treatment in high-risk groups. India plans to end TB well before the deadline set by the World Health organisation (WHO). However, this can only be achieved with effective strategies targeting LTBI. Multiple treatment regimens have been approved for LTBI treatment, and all have comparable efficacy. The selection of one regimen over the other depends on various factors, such as availability, risk of adverse events, age, and drug interactions. Recently, the WHO, as well as the Revised National TB Control Programme (RNTCP), have updated their guidelines on TB preventive treatment in 2020 and 2021, respectively. This review has been especially prepared to acknowledge the differences in approach to LTBI in developed and developing countries.

Factors Associated With Discontinuation of Tuberculosis Preventive Treatment: Post Hoc Analysis of 2 Randomized, Controlled Trials

BACKGROUND

Adherence to tuberculosis preventive treatment (TPT) is an important determinant of clinical benefit. We assessed the association of participant behaviors early in TPT with subsequent discontinuation.

METHODS

We used data from a phase 3 randomized trial and the preceding phase 2 trial to compare 4 months of rifampin to 9 months of isoniazid for TPT. We excluded participants whose providers discontinued TPT due to adverse events or tuberculosis disease. We analyzed 4 outcomes: discontinuing TPT within the first month of treatment, discontinuing TPT between the first and second month, discontinuing TPT after the second month, and completing treatment but not per protocol. We analyzed the association of outcomes with regimen and participant characteristics and 4 behavioral predictors of discontinuation recorded at the month 1 and month 2 follow-up visits: reporting symptoms of intolerance, missing >20% of doses, rescheduling appointments, and not bringing their medication bottle.

RESULTS

Overall, 6656 participants were included (phase 3, 5848; phase 2, 808), of whom 4318 (64.9%) completed treatment per protocol. Participant characteristics were inconsistently associated with discontinuation. Phase 3 trial participants with 1, 2, or 3-4 behavioral predictors at the month 1 follow-up had 5.0 (95% confidence interval, 3.6-6.7), 18.6 (13.3-26.1), and 79.4 (38.2-165.0), respectively, higher odds of discontinuing before the second month. The corresponding number of predictors at the month 2 follow-up had 1.8 (1.4-2.2), 4.7 (3.6-6.2), and 7.4 (4.6-11.9) higher odds of discontinuing before completing treatment; phase 2 findings were similar.

CONCLUSIONS

Four behavioral predictors recorded early in therapy were more strongly associated with subsequent discontinuation than participant characteristics, particularly when more than 1 behavioral predictor was recorded. Clinical Trials Registration. NCT00170209; NCT00931736.

Implementing the 4R and 9H regimens for TB preventive treatment in Indonesia

BACK GROUND:

The implementation of tuberculosis preventive treatment (TPT) is challenging especially in resource-limited settings. As part of a Phase 3 trial on TPT, we described our experience with the use of rifampicin for 4 months (4R) and isoniazid for 9 months (9H) in Indonesia.

METHODS:

In 2011–2017, children and adults with latent TB infection were randomised to either 4R or 9H and followed until 16 months after randomisation for children and 28 months for adults. The primary outcome was the treatment completion rate. Secondary outcomes were Grade 3–5 adverse events (AEs), active TB occurrence, and health costs.

RESULTS:

A total of 157 children and 860 adults were enrolled. The 4R treatment completion rate was significantly higher than that of 9H (78.7% vs. 65.5%), for a rate difference of 13.2% (95% CI 7.1–19.2). No Grade 3–5 AEs were reported in children; in adults, it was lower in 4R (0.4%) compared to 9H (2.8%). The incidence of active TB was lower with 4R than with 9H (0.09/100 person-year vs. 0.36/100 person-year) (rate difference: −0.36/100 person-year). The total cost per patient was lower for the 4R regimen than for the 9H regimen (USD151.9 vs. USD179.4 in adults and USD152.9 vs. USD206.5 in children)

CONCLUSIONS:

Completion and efficacy rates for 4R were better than for 9H. Compared to 9H, 4R was cheaper in all age groups, safer in adults and equally safe in children. The Indonesian TB program could benefit from these benefits of the 4R regimen.

Isoniazid or rifampicin preventive therapy with and without screening for subclinical TB: a modeling analysis

BACKGROUND

Short-course, rifamycin-based regimens could facilitate scale-up of tuberculosis preventive therapy (TPT), but it is unclear how stringently tuberculosis (TB) disease should be ruled out before TPT use.

METHODS

We developed a state-transition model of a TPT intervention among two TPT-eligible cohorts: adults newly diagnosed with HIV in South Africa (PWH) and TB household contacts in Pakistan (HHCs). We modeled two TPT regimens-4 months of rifampicin [4R] or 6 months of isoniazid [6H]-comparing each to a reference of no intervention. Before initiating TPT, TB disease was excluded either through symptom-only screening or with additional radiographic screening that could detect subclinical TB but might limit access to the TPT intervention. TPT's potential curative effects on both latent and subclinical TB were modeled, as were both acquisitions of resistance and prevention of drug-resistant disease. Although all eligible individuals received the screening and/or TPT interventions, the modeled TB outcomes comprised only those with latent or subclinical TB that would have progressed to symptomatic disease if untreated.

RESULTS

When prescribed after only symptom-based TB screening (such that individuals with subclinical TB were included among TPT recipients), 4R averted 45 active (i.e., symptomatic) TB cases (95% uncertainty range 24-79 cases or 40-89% of progressions to active TB) per 1000 PWH [17 (9-29, 43-94%) per 1000 HHCs]; 6H averted 37 (19-66, 52-73%) active TB cases among PWH [13 (7-23, 53-75%) among HHCs]. With this symptom-only screening, for each net rifampicin resistance case added by 4R, 12 (3-102) active TB cases were averted among PWH (37 [9-580] among HHCs); isoniazid-resistant TB was also reduced. Similarly, 6H after symptom-only screening increased isoniazid resistance while reducing overall and rifampicin-resistant active TB. Screening for subclinical TB before TPT eliminated this net increase in resistance to the TPT drug; however, if the screening requirement reduced TPT access by more than 10% (the estimated threshold for 4R among HHCs) to 30% (for 6H among PWH), it was likely to reduce the intervention's overall TB prevention impact.

CONCLUSIONS

All modeled TPT strategies prevent TB relative to no intervention, and differences between TPT regimens or between screening approaches are small relative to uncertainty in the outcomes of any given strategy. If most TPT-eligible individuals can be screened for subclinical TB, then pairing such screening with rifamycin-based TPT maximizes active TB prevention and does not increase rifampicin resistance. Where subclinical TB cannot be routinely excluded without substantially reducing TPT access, the choice of TPT regimen requires weighing 4R's efficacy advantages (as well as its greater safety and shorter duration that we did not directly model) against the consequences of rifampicin resistance in a small fraction of recipients.

Association between 9-month isoniazid prophylaxis of latent tuberculosis and severe hepatitis in patients treated with TNF inhibitors

To investigate associations between isoniazid for latent tuberculosis and risk of severe hepatitis, affecting patients with rheumatoid arthritis or ankylosing spondylitis whose treatment includes tumor necrosis factor inhibitors. Our self-controlled case series study analyzed Taiwan’s National Health Insurance Database from 2003 to 2015 to identify RA or AS patients, aged ≥ 20 years, receiving TNF inhibitors and a 9-month single isoniazid treatment. The outcome of interest was hospitalization due to severe hepatitis. We defined risk periods by isoniazid exposure (days): 1–28, 29–56, 57–84, 85–168, 169–252, and 253–280. To compare risk of severe hepatitis in exposed and non-exposed periods, we performed conditional Poisson regressions to generate incidence rate ratios (IRR) and 95% confidence intervals, with adjustment of patients’ baseline covariates including age, sex, HBV, HCV and related medication. Of 54,267 RA patients and 137,889 AS patients identified between 2000 and 2015, 11,221 (20.7%) RA and 4,208 (3.1%) AS patients underwent TNFi therapy, with 722 (5%) receiving isoniazid for latent tuberculosis. We identified 31 incident cases (4.3%) of hospitalization due to severe hepatitis. Of these hospitalization events, 5 occurred in the exposed periods, 25 occurred in the INH unexposed periods, and 1 occurred in the pre-exposure period. Compared with non-exposure, the risk of severe hepatitis was higher in exposed periods (incidence rate ratio [IRR]: 5.1, 95% CI: 1.57–16.55), especially 57–84 days (IRR: 17.29, 95% CI: 3.11–96.25) and 85–168 days (IRR:10.55, 95% CI: 1.90–58.51). The INH related fatal hepatotoxicity was not identified in our study. Our findings suggest an association between risk of severe hepatitis and exposure to isoniazid in patients with RA or AS under TNFi therapy, particularly within the exposed period 57–168 days. A close monitoring of liver function is mandatory to minimize the risk, especially within the first 6 months after initiation of 9 months isoniazid.

Tuberculosis preventive therapy for people living with HIV: A systematic review and network meta-analysis

BACKGROUND

Tuberculosis (TB) preventive therapy (TPT) is an essential component of care for people living with HIV (PLHIV). We compared efficacy, safety, completion, and drug-resistant TB risk for currently recommended TPT regimens through a systematic review and network meta-analysis (NMA) of randomized trials.

METHODS AND FINDINGS

We searched MEDLINE, Embase, and the Cochrane Library from inception through June 9, 2020 for randomized controlled trials (RCTs) comparing 2 or more TPT regimens (or placebo/no treatment) in PLHIV. Two independent reviewers evaluated eligibility, extracted data, and assessed the risk of bias. We grouped TPT strategies as follows: placebo/no treatment, 6 to 12 months of isoniazid, 24 to 72 months of isoniazid, and rifamycin-containing regimens. A frequentist NMA (using graph theory) was carried out for the outcomes of development of TB disease, all-cause mortality, and grade 3 or worse hepatotoxicity. For other outcomes, graphical descriptions or traditional pairwise meta-analyses were carried out as appropriate. The potential role of confounding variables for TB disease and all-cause mortality was assessed through stratified analyses. A total of 6,466 unique studies were screened, and 157 full texts were assessed for eligibility. Of these, 20 studies (reporting 16 randomized trials) were included. The median sample size was 616 (interquartile range [IQR], 317 to 1,892). Eight were conducted in Africa, 3 in Europe, 3 in the Americas, and 2 included sites in multiple continents. According to the NMA, 6 to 12 months of isoniazid were no more efficacious in preventing microbiologically confirmed TB than rifamycin-containing regimens (incidence rate ratio [IRR] 1.0, 95% CI 0.8 to 1.4, p = 0.8); however, 6 to 12 months of isoniazid were associated with a higher incidence of all-cause mortality (IRR 1.6, 95% CI 1.2 to 2.0, p = 0.02) and a higher risk of grade 3 or higher hepatotoxicity (risk difference [RD] 8.9, 95% CI 2.8 to 14.9, p = 0.004). Finally, shorter regimens were associated with higher completion rates relative to longer regimens, and we did not find statistically significant differences in the risk of drug-resistant TB between regimens. Study limitations include potential confounding due to differences in posttreatment follow-up time and TB incidence in the study setting on the estimates of incidence of TB or all-cause mortality, as well as an underrepresentation of pregnant women and children.

CONCLUSIONS

Rifamycin-containing regimens appear safer and at least as effective as isoniazid regimens in preventing TB and death and should be considered part of routine care in PLHIV. Knowledge gaps remain as to which specific rifamycin-containing regimen provides the optimal balance of efficacy, completion, and safety.

The latent tuberculosis cascade-of-care among people living with HIV: A systematic review and meta-analysis

BACKGROUND

Tuberculosis preventive therapy (TPT) reduces TB-related morbidity and mortality in people living with HIV (PLHIV). Cascade-of-care analyses help identify gaps and barriers in care and develop targeted solutions. A previous latent tuberculosis infection (LTBI) cascade-of-care analysis showed only 18% of persons in at-risk populations complete TPT, but a similar analysis for TPT among PLHIV has not been completed. We conducted a meta-analysis to provide this evidence.

METHODS AND FINDINGS

We first screened potential articles from a LTBI cascade-of-care systematic review published in 2016. From this study, we included cohorts that reported a minimum of 25 PLHIV. To identify new cohorts, we used a similar search strategy restricted to PLHIV. The search was conducted in Medline, Embase, Health Star, and LILACS, from January 2014 to February 2021. Two authors independently screened titles and full text and assessed risk of bias using the Newcastle-Ottawa Scale for cohorts and Cochrane Risk of Bias for cluster randomized trials. We meta-analyzed the proportion of PLHIV completing each step of the LTBI cascade-of-care and estimated the cumulative proportion retained. These results were stratified based on cascades-of-care that used or did not use LTBI testing to determine eligibility for TPT. We also performed a narrative synthesis of enablers and barriers of the cascade-of-care identified at different steps of the cascade. A total of 71 cohorts were included, and 70 were meta-analyzed, comprising 94,011 PLHIV. Among the PLHIV included, 35.3% (33,139/94,011) were from the Americas and 29.2% (27,460/94,011) from Africa. Overall, 49.9% (46,903/94,011) from low- and middle-income countries, median age was 38.0 [interquartile range (IQR) 34.0;43.6], and 65.9% (46,328/70,297) were men, 43.6% (29,629/67,947) were treated with antiretroviral therapy (ART), and the median CD4 count was 390 cell/mm3 (IQR 312;458). Among the cohorts that did not use LTBI tests, the cumulative proportion of PLHIV starting and completing TPT were 40.9% (95% CI: 39.3% to 42.7%) and 33.2% (95% CI: 31.6% to 34.9%). Among cohorts that used LTBI tests, the cumulative proportions of PLHIV starting and completing TPT were 60.4% (95% CI: 58.1% to 62.6%) and 41.9% (95% CI:39.6% to 44.2%), respectively. Completion of TPT was not significantly different in high- compared to low- and middle-income countries. Regardless of LTBI test use, substantial losses in the cascade-of-care occurred before treatment initiation. The integration of HIV and TB care was considered an enabler of the cascade-of-care in multiple cohorts. Key limitations of this systematic review are the observational nature of the included studies, potential selection bias in the population selection, only 14 cohorts reported all steps of the cascade-of-care, and barriers/facilitators were not systematically reported in all cohorts.

CONCLUSIONS

Although substantial losses were seen in multiple stages of the cascade-of-care, the cumulative proportion of PLHIV completing TPT was higher than previously reported among other at-risk populations. The use of LTBI testing in PLHIV in low- and middle-income countries was associated with higher proportion of the cohorts initiating TPT and with similar rates of completion of TPT.