MedWire News: Tumor necrosis factor (TNF) antagonists are more likely to be successful for the treatment of psoriasis during the initial year of treatment than they are to cause serious toxicity, quantitative benefit-risk assessment data show.
Based on published results from controlled clinical trials, Richard Langley (Dalhousie University, Halifax, Canada) and colleagues report that point estimates of the number needed to treat (NNT) were generally two orders of magnitude smaller than the number-needed-to-harm (NNH) values for the three TNF antagonists adalimumab, etanercept, and infliximab.
The researchers carried out integrated analyses, including open-label safety data, of published trials of the three drugs in order to calculate the NNT for efficacy measures and the NNH for adverse events.
Patients participating in the trials, which lasted for between 16 and 24 weeks, had moderate–to–severe psoriasis, with an average baseline Psoriasis Area and Severity Index (PASI) score of at least 18 and an average baseline body surface area involvement of 26% or more.
Based on efficacy data for a 75% improvement in PASI score, the NNT values were 1.6 for adalimumab, 3.2 for etanercept 50 mg weekly, 2.3 for etanercept 50 mg twice weekly, and 1.4 for infliximab.
For serious non-infectious, serious infectious, and malignant adverse events, the point estimates of the NNHs ranged from 99 to 240 for adalimumab, 183 to 324 for etanercept 50 mg twice weekly, 14 to 511 for etanercept 50 mg weekly, and 99 for infliximab.
The researchers note in the British Journal of Dermatology that 95% confidence intervals (CIs) for all the calculated NNHs overlapped, and the upper bounds reached infinity.
This indicates that there were no significant differences in risks for these types of adverse events between any active treatment and placebo, and in some cases the risks even extended to negative values suggesting the possibility of reduced risk for toxicity with treatment, they explain.
The researchers note: “Even with conservative, or pessimistic, estimates of the NNHs at the lower ranges of the 95% CIs, a comparison of NNHs versus NNTs supports the intuitive assessment that the likelihood of these types of serious toxicities is far less than the likelihood of treatment success.”
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