BACKGROUND & AIMS: Regulatory assessments of drug risks do not routinely consider patient preferences, despite evidence that some patients are willing to accept increased side-effect risk in exchange for therapeutic benefits. The aim of this study is to estimate the willingness of Crohn's disease (CD) patients to accept life-threatening adverse event risks in exchange for CD symptom relief.METHODS: Patients with CD completed choice-format conjoint trade-off tasks involving hypothetical treatments with varying efficacy and risk levels. The treatment features included daily symptoms and activity limitations, serious complications (fistulas, abscesses, bowel obstructions), time between flare-ups, oral steroid use and risk of 3 serious adverse events (SAEs) known to be associated with CD treatment (progressive multifocal leukoencephalopathy (PML), serious infections, and lymphoma). The mean maximum acceptable annual risk (MAR) for each of the SAEs was calculated for various levels of clinical benefit.RESULTS: Daily symptom severity was the most important factor in treatment preferences. Higher MAR was observed for trade-off tasks involving higher levels of clinical benefit. The MAR was similar across the 3 SAEs. For improvements from severe daily symptoms to remission and from moderate daily symptoms to remission, the MARs ranged from 0.69% to 0.81% and from 0.39% to 0.55%, respectively.CONCLUSIONS: Patients with CD have well-defined preferences among treatment attributes and are willing to accept tradeoffs among attributes. The patients indicated they are willing to accept elevated SAE risks in exchange for clinical efficacy. The perspective of the patients on the benefit versus risk balance can assist in making treatment and regulatory decisions.