Table 1 Descriptions of the statements and factors

F1: Knowledge of CTs

I know what a CT means

Each new drug has been studied with patients before it becomes available via pharmacies

CTs are always assessed beforehand by a research ethics committee

Participation in a CT is always voluntary

A potential CT participant signs a consent document before taking part in the research

The research participant may at any point terminate their participation in the CT

A clinical trial may include procedures differing from ordinary treatment

Clinical trials are mostly funded by a pharmaceutical corporation

The essential goal of clinical treatments is to find better medication for future patients

F2: Willingness

New PD medications are usually studied in comparative trials (an old drug is compared to a new substance or a placebo); I would like to participate in this kind of CT

I would participate in a CT if I did not receive enough information about the CT and the investigational drug

I would participate in a CT even if because of that I would need to go to a physician’s office much more often than in ordinary care

I would participate in a CT in which there were a possibility of receiving a placebo (placebos do not contain any active ingredient)

I would participate in clinical trials because it would enable me to help other patients with Parkinson’s disease

F3: Therapeutic misconception

Usually, CTs are aimed primarily at seeking the best medication for the research participants

I would participate in a CT only if the treating physician also is the investigator

I would like to participate in CTs in order to determine the continuation of my current treatment relationship

I would like to participate in a CT because then I would receive more thorough monitoring relative to standard treatment – usually clinical trials are aimed primarily at seeking the best medication for the research participants

I would participate in a CT if that guaranteed me new and improved medication

I would participate in a CT only if I were not satisfied with my current medication

In CTs, all participants always receive a new effective agent

In CTs, the physician conducting the research is aware of whether the participant is receiving a new drug, a placebo (which does not include an effective agent), or an older Parkinson’s disease medication

In CTs, the physician conducting the research may choose which drug the participant receives

The patient participating in the research may often choose which drug they receive

I would participate in a CT, because then I would receive the best treatment for me

I would participate only in a CT in which at least one of the drugs being compared has been shown to be effective