Objectives: To perform a NNT analysis of patients with active RA despite background MTX therapy in order to achieve an ACR50 and ACR70 response at 1 year with abatacept, adalimumab, etanercept, or infliximab in combination with MTX, as compared to MTX monotherapy.
Methods: Efficacy data was extracted from published clinical trials with similar study designs. While some differences existed in baseline disease duration, HAQ and swollen and tender joint count, in general, the studies had similar patient characteristics. The NNT to achieve an ACR 50 or ACR 70 response at one year was calculated as the reciprocal of the absolute risk reduction (ARR) of biologic plus MTX as compared to MTX monotherapy per approved dose. Ninety-five percent confidence intervals (CI) were calculated to estimate the uncertainty in the NNT.
Results: The table presents the data for ACR 50 and ACR 70 scores at one year. The NNTs range from 3 to 13 and the 95% CI suggest little variation in the NNTs across the biologics, except for infliximab at the 3 mg/kg dose. For example, the incremental benefit to reach ACR 50 with abatacept plus MTX as compared to MTX is 30%, resulting in a NNT of 3 (rounded) [95% CI: 2.7, 4.5].
Conclusions: The NNT analysis is potentially a useful tool in evaluating clinical trial results The favorable NNT estimates that are derived from clinical trials provide evidence that only a few patients need to be treated with each of the biologics in order to achieve clinically important improvements over MTX.
|ACR 50 - 1 year||Biologic + MTX||Placebo + MTX||ARR||NNT||95% CI|
|Infliximab - 3mg/kg Q 8||21%||8%||13%||8||4.3, 37.1|
|Infliximab - 10mg/kg Q 4||38%||8%||30%||3||2.4, 5.9|
|ACR 70 - 1 year||Biologic + MTX||Placebo + MTX||ARR||NNT||95% CI|
|Infliximab - 3mg/kg Q 8||10%||2%||8%||13||6.7, 98.3|
|Infliximab - 10mg/kg Q 4||19%||2%||17%||6||3.9, 12.1|
C.O. Bingham, Bristol Myers Squibb Company, 2; Amgen, Inc., 2; Abbott Laboratories, 2; Genentech, Inc., 2; Centocor, Inc, 2; Bristol Myers Squibb Company, 5; Abbott Laboratories, 5; Amgen, Inc, 5; J. Barnes, None; Y. Yuan, None; A. Beresniak, None.