Using 'number needed to treat' to help conceptualize the magnitude of benefit and risk of tumour necrosis factor-α inhibitors for patients with severe psoriasis

Background Risks and benefits of tumour necrosis factor (TNF) alpha inhibitors are often presented using statistical descriptions that are difficult to translate directly for patients into a clinically meaningful context. Objectives To illustrate the risks and benefits of TNF alpha inhibitors in relation to risks that patients understand. Methods We performed a number needed to treat analysis for patients with psoriasis on TNF alpha inhibitors via a Medline and Embase search. We determined the number needed to benefit and the number needed to harm with TNF alpha inhibitor treatment. We compared the risk of serious adverse events from treatment with a TNF alpha inhibitor to the risk of death from driving a car. The risk analyses were limited to the risks of tuberculosis, lymphoma and demyelinating disease. Results The numbers needed to benefit were 2.1 for etanercept, 1.4 for infliximab, and 1.6 for adalimumab. Depending on the adverse event, the numbers needed to harm ranged from 380 to 360 000 treated patients per year. Screening prior to the initiation of TNF alpha inhibitor therapy reduces risk of tuberculosis. Patients are about as likely to die in a car accident as to have a serious adverse event from treatment with a TNF alpha inhibitor. Conclusions All three of the TNF alpha antagonists have remarkable efficacy in patients with severe psoriasis. The risks of serious adverse events are relatively rare and comparable to the risks patients take on a regular basis such as driving a car. For many patients with severe psoriasis, the benefits of TNF alpha inhibitors may greatly outweigh the risks.