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Years‐needed‐to‐treat to add 1 year of life: a new metric to estimate treatment effects in randomized trials
Author(s) -
Levy Wayne C.,
Mozaffarian Dariush,
Linker David T.,
Kenyon Kenneth W.,
Cleland John G.F.,
Komajda Michel,
Remme Willem J.,
TorpPedersen Christian,
Metra Marco,
PooleWilson Philip A.
Publication year - 2009
Publication title -
european journal of heart failure
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.149
H-Index - 133
eISSN - 1879-0844
pISSN - 1388-9842
DOI - 10.1093/eurjhf/hfn048
Subject(s) - medicine , number needed to treat , randomized controlled trial , confidence interval , life expectancy , hazard ratio , carvedilol , relative risk , heart failure , population , environmental health
Aims A standard metric to estimate absolute treatment effects is numbers‐needed‐to‐treat (NNT), which implicitly assumes that all benefits reverse at trial‐end. However, in‐trial survival benefits typically do not reverse until long after trial‐end, so that NNT will substantially underestimate lifetime benefits. Methods and results We developed a new concept, years‐needed‐to‐treat (YNT) to add 1 year of life, that quantifies the expected average life expectancy for two treatments including the estimated years of life remaining post‐trial. Numbers‐needed‐to‐treat and YNT were calculated in the COMET trial, in which carvedilol vs. metoprolol tartrate resulted in 17% lower mortality over 4.8 years. A multivariate Cox model was used to predict survival. Remaining years of life were estimated using the mortality‐life‐table method. At trial‐end, survival was 9% higher in the carvedilol arm. Assuming that patients remained on the same therapy post‐trial, the average total years of life for carvedilol vs. metoprolol were 10.63 ± 0.19 vs. 9.48 ± 0.18 ( P < 0.0001) or 1.15 (95% confidence interval 0.64–1.66) additional years of life. The YNT was 9.2, indicating that 9.2 person‐years of treatment added 1 person‐year of life, compared with NNT of 59. Conclusion Compared with NNT, the YNT method more accurately accounts for potential long‐term benefits of interventions in randomized trials.