Table 1.

Attributes and levels of treatment options

Treatment attribute	Levels describing no treatment option (%)	Levels describing treatment option (%)
Chance of developing rheumatoid arthritis	60	20
Chance of mild side effects	0	2, 4, 5, 7 or 10*
Chance of a serious infection due to treatment	0	1, 1.5, 2, 3 or 5*
Chance of a serious side effect that is potentially irreversible	0	0.001, 0.01, 0.02, 0.05 or 0.1*

*One by one, each treatment risk was systematically increased or decreased across these levels (depending on the participant’s initial response; baseline level indicated in bold type) until the participant switches choice (choosing no treatment, instead of a preventive treatment, or vice versa).