Abstract
Objective
This study aimed to test the number needed to treat to benefit (NNTB) and to harm (NNTH), and the likelihood to be helped or harmed (LHH) when assessing benefits, risks, and benefit–risk ratios of disease-modifying treatments (DMTs) approved for relapsing–remitting multiple sclerosis (RRMS).
Methods
In May 2016, we conducted a systematic review using the PubMed and Cochrane Central Register of Controlled Trials databases to identify phase III, randomized controlled trials with a duration of ≥2 years that assessed first-line (dimethyl fumarate [DMF], glatiramer acetate [GA], β-interferons [IFN], and teriflunomide) or second-line (alemtuzumab, fingolimod, and natalizumab) DMTs in patients with RRMS. Meta-analyses were performed to estimate relative risks (RRs) on annualized relapse rate (ARR), proportion of relapse-free patients (PPR-F), disability progression (PP-F-CDPS3M), and safety outcomes. NNTB and NNTH values were calculated applying RRs to control event rates. LHH was calculated as NNTH/NNTB ratio.
Results
The lowest NNTBs on ARR, PPR-F, and PP-F-CDPS3M were found with IFN-β-1a-SC (NNTB 3, 95 % CI 2–4; NNTB 7, 95 % CI 4–18; NNTB 4, 95 % CI 3–7, respectively) and natalizumab (NNTB 2, 95 % CI 2–3; NNTB 4, 95 % CI 3–6; NNTB 9, 95 % CI 6–19, respectively). The lowest NNTH on adverse events leading to treatment discontinuation was found with IFN-β-1b (NNTH 14, 95 % 2–426) versus placebo; a protective effect was noted with alemtuzumab versus IFN-β-1a-SC (NNTB 22, 95 % 17–41). LHHs >1 were more frequent with IFN-β-1a-SC and natalizumab.
Conclusions
These metrics may be valuable for benefit–risk assessments, as they reflect baseline risks and are easily interpreted. Before making treatment decisions, clinicians must acknowledge that a higher RR reduction with drug A as compared with drug B (versus a common comparator in trial A and trial B, respectively) does not necessarily mean that the number of patients needed to be treated for one patient to encounter one aditional outcome of interest over a defined period of time is lower with drug A than with drug B. Overall, IFN-β-1a-SC and natalizumab seem to have the most favorable benefit–risk ratios among first- and second-line DMTs, respectively.
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Acknowledgments
The authors thank Biogen Idec Portugal for the supplied data (population exposure and number of PML cases reported with DMF).
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Diogo Mendes declares that he has no conflict of interest. Carlos Alves declares that he has no conflict of interest. Francisco Batel-Marques declares that he has no conflict of interest.
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This study was not financially supported by any institution.
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Mendes, D., Alves, C. & Batel-Marques, F. Benefit–Risk of Therapies for Relapsing–Remitting Multiple Sclerosis: Testing the Number Needed to Treat to Benefit (NNTB), Number Needed to Treat to Harm (NNTH) and the Likelihood to be Helped or Harmed (LHH): A Systematic Review and Meta-Analysis. CNS Drugs 30, 909–929 (2016). https://doi.org/10.1007/s40263-016-0377-9
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DOI: https://doi.org/10.1007/s40263-016-0377-9