Applying a Risk-benefit Analysis to Outcomes in Tuberculosis Clinical Trials

Comparison of Various Pharmacologic Agents in the Management of Hemodynamically Significant Patent Ductus Arteriosus in Preterm: A Network Meta-Analysis and Risk-Benefit Analysis

Introduction

Various pharmacological treatments are available for preterm infants with patent ductus arteriosus (PDA), but their risks and benefits are controversial. This study aimed to identify the best treatment for PDA using network meta-analysis (NMA) and risk-benefit assessment (RBA).

Methods

Relevant randomized controlled trials (RCTs) were identified from MEDLINE, Scopus, and the Cochrane Library. RCTs were eligible if they were studied for preterm or low birth weight infants with presymptomatic PDA and hemodynamically significant PDA (hsPDA). The outcomes were PDA closure for a benefit and the composite risk outcome of adverse effects (AEs) for risk. An NMA was used to estimate the treatment effects of benefit and risk. The RBA helped to incorporate the risk and benefits of multiple treatments. Then, an incremental risk-benefit ratio was calculated by dividing the incremental risk by benefit using data from NMA, and they were jointly simulated using Monte Carlo methods. Finally, net clinical benefit (NCB) probability curves were constructed at varying acceptability thresholds.

Results

Seventy RCTs with hsPDA were eligible considering 13 different interventions, but data on presymptomatic PDA were not enough for pooling. The clustered ranking plot from NMA indicated that 3 interventions (i.e., high-dose oral ibuprofen, standard-dose oral acetaminophen, and standard-dose oral ibuprofen) yielded high PDA closure and low AE. These three treatments and additional commonly used indomethacin were considered in the RBA. Given an acceptable threshold of 25% or having one AE out of four PDA closures, high-dose oral ibuprofen had a 36% chance of having the highest NCB, followed by standard-dose oral acetaminophen (27%), and oral ibuprofen (23.7%). Subgroup analysis indicated that the chances of having the highest NCB of GA ≥28 weeks were similar to that of all available studies. The best for GA <28 weeks, no data for high-dose oral ibuprofen, was standard-dose oral acetaminophen, followed by standard-dose oral ibuprofen.

Conclusions

Trade-off RBA indicated that high-dose oral ibuprofen might be the best treatment for preterm, GA ≥28 weeks, with hsPDA followed by the standard-dose oral acetaminophen and ibuprofen. Preferably, optimal high doses, postnatal age to start treatment, and long-term outcomes are needed to study in the future.

Using a Composite Maternal-Infant Outcome Measure in Tuberculosis-Prevention Studies Among Pregnant Women

BACKGROUND

Tuberculosis (TB-)-preventive therapy (TPT) among pregnant women reduces risk of TB in mothers and infants, but timing of initiation should consider potential adverse effects. We propose an analytical approach to evaluate the risk-benefit of interventions.

METHODS

A novel outcome measure that prioritizes maternal and infant events was developed with a 2-stage Delphi survey, where a panel of stakeholders assigned scores from 0 (best) to 100 (worst) based on perceived desirability. Using data from TB APPRISE, a trial among pregnant women living with human immunodeficiency virus (WLWH) that randomized the timing of initiation of isoniazid, antepartum versus postpartum, was evaluated.

RESULTS

The composite outcome scoring/ranking system categorized mother-infant paired outcomes into 8 groups assigned identical median scores by stakeholders. Maternal/infant TB and nonsevere adverse pregnancy outcomes were assigned similar scores. Mean (SD) composite outcome scores were 43.7 (33.0) and 41.2 (33.7) in the antepartum and postpartum TPT initiation arms, respectively. However, a modifying effect of baseline antiretroviral regimen was detected (P = .049). When women received nevirapine, composite scores were higher (worse outcomes) in the antepartum versus postpartum arms (adjusted difference, 14.3; 95% confidence interval [CI], 2.4-26.2; P = .02), whereas when women received efavirenz there was no difference by timing of TPT (adjusted difference, .62; 95% CI, -3.2-6.2; P = .53).

CONCLUSIONS

For TPT, when used by otherwise healthy persons, preventing adverse events is paramount from the perspective of stakeholders. Among pregnant WLWH in high-TB-burden regions, it is important to consider the antepartum antiretroviral regimen taken when deciding when to initiate TPT. Clinical Trials Registration. NCT01494038 (IMPAACT P1078).

A framework for considering the risk-benefit trade-off in designing noninferiority trials using composite outcome approaches

When a new treatment regimen is expected to have comparable or slightly worse efficacy to that of the control regimen but has benefits in other domains such as safety and tolerability, a noninferiority (NI) trial may be appropriate but is fraught with difficulty in justifying an acceptable NI margin that is based on both clinical and statistical input. To overcome this, we propose to utilize composite risk-benefit outcomes that combine elements from domains of importance (eg, efficacy, safety, and tolerability). The composite outcome itself may be analyzed using a superiority framework, or it can be used as a tool at the design stage of a NI trial for selecting an NI margin for efficacy that balances changes in risks and benefits. In the latter case, the choice of NI margin may be based on a novel quantity called the maximum allowable decrease in efficacy (MADE), defined as the marginal difference in efficacy between arms that would yield a null treatment effect for the composite outcome given an assumed distribution for the composite outcome. We observe that MADE: (1) is larger when the safety improvement for the experimental arm is larger, (2) depends on the association between the efficacy and safety outcomes, and (3) depends on the control arm efficacy rate. We use a numerical example for power comparisons between a superiority test for the composite outcome vs a noninferiority test for efficacy using the MADE as the NI margin, and apply the methods to a TB treatment trial.

Methodologies for pragmatic and efficient assessment of benefits and harms: Application to the SOCRATES trial

BACKGROUND/AIMS

Standard approaches to trial design and analyses can be inefficient and non-pragmatic. Failure to consider a range of outcomes impedes evidence-based interpretation and reduces power. Traditional approaches synthesizing information obtained from separate analysis of each outcome fail to incorporate associations between outcomes and recognize the cumulative nature of outcomes in individual patients, suffer from competing risk complexities during interpretation, and since efficacy and safety analyses are often conducted on different populations, generalizability is unclear. Pragmatic and efficient approaches to trial design and analyses are needed.

METHODS

Approaches providing a pragmatic assessment of benefits and harms of interventions, summarizing outcomes experienced by patients, and providing sample size efficiencies are described. Ordinal outcomes recognize finer gradations of patient responses. Desirability of outcome ranking is an ordinal outcome combining benefits and harms within patients. Analysis of desirability of outcome ranking can be based on rank-based methodologies including the desirability of outcome ranking probability, the win ratio, and the proportion in favor of treatment. Partial credit analyses, involving grading the levels of the desirability of outcome ranking outcome similar to an academic test, provides an alternative approach. The methodologies are demonstrated using the acute stroke or transient ischemic attack treated with aspirin or ticagrelor and patient outcomes study (SOCRATES; NCT01994720), a randomized clinical trial.

RESULTS

Two 5-level ordinal outcomes were developed for SOCRATES. The first was based on a modified Rankin scale. The odds ratio is 0.86 (95% confidence interval = 0.75, 0.99; p = 0.04) indicating that the odds of worse stroke categorization for a trial participant assigned to ticagrelor is 0.86 times that of a trial participant assigned to aspirin. The 5-level desirability of outcome ranking outcome incorporated and prioritized survival; the number of strokes, myocardial infarction, and major bleeding events; and whether a stroke event was disabling. The desirability of outcome ranking probability and win ratio are 0.504 (95% confidence interval = 0.499, 0.508; p = 0.10) and 1.11 (95% confidence interval = 0.98, 1.26; p = 0.10), respectively, implying that the probability of a more desirable result with ticagrelor is 50.4% and that a more desirable result occurs 1.11 times more frequently on ticagrelor versus aspirin.

CONCLUSION

Ordinal outcomes can improve efficiency through required pre-specification, careful construction, and analyses. Greater pragmatism can be obtained by composing outcomes within patients. Desirability of outcome ranking provides a global assessment of the benefits and harms that more closely reflect the experience of patients. The desirability of outcome ranking probability, the proportion in favor of treatment, the win ratio, and partial credit can more optimally inform patient treatment, enhance the understanding of the totality of intervention effects on patients, and potentially provide efficiencies over standard analyses. The methods provide the infrastructure for incorporating patient values and estimating personalized effects.

Risk-benefit analysis of tuberculosis infection testing for household contact management in high-burden countries: a mathematical modelling study

BACKGROUND

Preventive therapy for tuberculosis reduces the risk of disease in people who have been infected but who are not sick. Countries with a high burden of tuberculosis that are expanding preventive therapy use must decide how tuberculosis infection testing should be used for risk stratification among household contacts of patients with tuberculosis.

METHODS

We modelled the risks of tuberculosis disease and severe adverse events, comparing the following two preventive therapy strategies: preventive therapy for all household contacts, or preventive therapy for only household contacts with a positive tuberculin skin test (TST) result. We used data from clinical trials and literature on tuberculosis natural history to model outcomes, assuming different preventive therapy regimens, ages, and TST positivity prevalence.

FINDINGS

Assuming 25% prevalence of TST positivity among 1000 household contacts aged 0-17 years, a treat-all approach with isoniazid and rifapentine compared with a treat-TST-only approach led to 13 fewer incident tuberculosis cases (IQR -5 to -18) and four additional severe adverse events (2 to 6). With rifampicin, the difference was 11 fewer incident tuberculosis cases (-3 to -17) and two additional severe adverse events (1 to 3). For adults, a treat-all approach led to fewer incident tuberculosis cases, and additional adverse events increased with age. Assuming 25% prevalence of TST positivity among adult contacts, a treat-all approach would lead to around two fewer tuberculosis cases per 1000 contacts for all regimens; the number of additional severe adverse events ranged from seven (IQR 5 to 8) for 18 to 34-year-olds treated with rifampicin to 63 (50 to 74) for people older than 64 years treated with isoniazid and rifapentine. A rifampicin-only regimen was associated with the fewest additional severe adverse events (seven [IQR 5 to 8] per 1000 adults aged 18-34 years and 35-64 years, and 17 [9 to 23] per 1000 adults older than 64 years).

INTERPRETATION

Based on the available data, giving preventive therapy to all household contacts would probably reduce the incidence of tuberculosis cases in high-burden settings. Adverse events could be minimised by using non-isoniazid regimens and, in adults older than 18 years, focusing treatment on individuals with a positive infection test.

FUNDING

Bill & Melinda Gates Foundation, UK Medical Research Council, and UK Department for International Development.