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An alternative approach for estimating the number needed to treat for survival endpoints.

ABSTRACT: To investigate the issues of the NNT based on the absolute risk reduction (ARR), namely NNTARR; and to propose an alternative definition and an estimation procedure based on the restricted mean survival time (RMST), namely NNTRMST, for RCTs. Three recent clinical trials with survival endpoints, representing different scenarios, were selected to compare the performance of the NNTARR and NNTRMST. For each trial, both versions of NNT were estimated using the reconstructed individual-level data, and the average life gain (ALG) was derived to show the differences between the NNTARR and NNTRMST. Four hypothetical scenarios were constructed to further explore the advantages and disadvantages of each definition of the NNT for survival endpoints. For the illustrative trial examples, the NNTARR failed to capture the profile of the treatment effect over time as it is calculated at a specific time point. Sometimes it may even result in misinterpretations of the treatment benefit. In particular, when either the observed event rates are low, the two survival curves cross, or a mixture of survival patterns exist. In contrast, the NNTRMST based on the average survival (or event-free) time can quantify the treatment effect more accurately and its interpretation is more intuitive and clinically meaningful. The NNTRMST can be used as an alternative measure for quantifying treatment effect in RCTs, especially so in the case of the ALG, which helps practitioners to better understand the magnitude of the benefit conferred by treatment.

SUBMITTER: Yang Z

PROVIDER: S-EPMC6799908 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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An alternative approach for estimating the number needed to treat for survival endpoints.

Yang Zhao Z Yin Guosheng G

PloS one 20191018 10

To investigate the issues of the NNT based on the absolute risk reduction (ARR), namely NNTARR; and to propose an alternative definition and an estimation procedure based on the restricted mean survival time (RMST), namely NNTRMST, for RCTs. Three recent clinical trials with survival endpoints, representing different scenarios, were selected to compare the performance of the NNTARR and NNTRMST. For each trial, both versions of NNT were estimated using the reconstructed individual-level data, and ...[more]

PMID: 31626655

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Project description:Objective:Schizophrenia clinical trials commonly measure observed changes in Positive and Negative Syndrome Scale (PANSS) total score. However, it is more intuitive to think of response vs nonresponse, a binary outcome. Assessing binary outcomes enables calculation of number needed to treat (NNT) for therapeutic outcomes, number needed to harm (NNH) for adverse outcomes, and likelihood to be helped or harmed (LHH) to demonstrate benefit/risk tradeoffs. Here, NNT, NNH, and LHH were used to evaluate the clinical usefulness of aripiprazole lauroxil in patients with an acute schizophrenia exacerbation. Methods:Categorical efficacy and tolerability data were taken from the pivotal Phase 3 trial evaluating aripiprazole lauroxil for treatment of an acute exacerbation of schizophrenia. NNT and NNH values, with 95% CIs, were calculated in this post hoc analysis. Results:Using the intent-to-treat population for the pooled doses of aripiprazole lauroxil (441 mg [n=196] and 882 mg [n=204] q4w), responder rates (?30% improvement from baseline PANSS total score) were 35.3% for aripiprazole lauroxil arms vs 18.4% for placebo (n=196), yielding a NNT of 6 (95% CI: 5-11). Discontinuation rates due to adverse events (AEs) were higher among patients randomized to placebo than to either aripiprazole lauroxil dose. Akathisia was the only AE with an incidence ?5% in each aripiprazole lauroxil group and at least twice that of placebo (11.6%, 11.5%, and 4.3% of the patients receiving aripiprazole lauroxil 441 mg, 882 mg, and placebo, respectively), producing a NNH of 14 (95% CI: 9-33) for pooled aripiprazole lauroxil doses vs placebo. Calculating LHH for therapeutic response vs akathisia, aripiprazole lauroxil was 2.3 times more likely to result in a therapeutic response than an incident of akathisia. Conclusion:Using metrics of NNT, NNH, and LHH, aripiprazole lauroxil was an efficacious and well-tolerated intervention in a pivotal study in patients with an acute schizophrenia exacerbation.

Project description:IntroductionSubcutaneous galcanezumab was an effective, well-tolerated preventive treatment for adults with episodic (EM) or chronic migraine (CM) in 4 phase 3 randomized controlled trials: EVOLVE-1, EVOLVE-2, REGAIN, and CONQUER. Number needed to treat (NNT) and to harm (NNH) are metrics of effect size used to evaluate benefit-risk profiles. This study evaluated NNT, NNH, and benefit-risk profiles (measured as likelihood to be helped or harmed, LHH) of galcanezumab 120 mg versus placebo in patients with EM or CM.MethodsPrimary efficacy outcomes were responses defined as ≥ 30%, ≥ 50%, and ≥ 75% reductions from baseline in number of monthly migraine headache days in patients with EM (EVOLVE-1; EVOLVE-2; CONQUER) and CM (REGAIN; CONQUER); corresponding NNTs to achieve respective responses; and corresponding NNHs for discontinuations due to adverse events (DCAEs) among the safety population. Secondary efficacy outcomes were responses for patients with ≥ 2 failed prior preventive treatments due to lack of efficacy and/or for tolerability reasons. All LHHs were based on ≥ 50% response and DCAEs.ResultsDuring double-blind treatment periods with galcanezumab 120 mg, NNT to achieve ≥ 30% and ≥ 50% responses ranged from 4 to 10 and NNT to achieve ≥ 75% responses ranged from 5 to 23 in individual trials. NNH ranged from 93 to 1000, while LHH ranged from 18.6 to 104.6. NNTs were generally more robust among patients with EM than with CM; however, in patients with failure of ≥ 2 prior preventive treatments, NNTs to achieve ≥ 30% and ≥ 50% responses were similar between patients with CM and EM. NNHs were imputed as 1000 for both migraine types. Resulting LHHs were 178.8 (EM) and 127 (CM).ConclusionAcross 4 trials, galcanezumab 120 mg demonstrated a favorable benefit-risk profile versus placebo, based on low NNTs to achieve response and high NNHs associated with DCAEs. LHH values consistently far exceeded 1.Trial registration numbersEVOLVE-1: ClinicalTrials.gov identifier, NCT02614183; EVOLVE-2: ClinicalTrials.gov identifier, NCT02614196; REGAIN: ClinicalTrials.gov identifier, NCT02614261; CONQUER: ClinicalTrials.gov identifier, NCT03559257.

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An alternative approach for estimating the number needed to treat for survival endpoints.

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An alternative approach for estimating the number needed to treat for survival endpoints.

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