Table 1.

Strategies to exclude professional subjects.

Strategy		Outcome
Advertising	•Avoid mentioning payments in media campaigns. •Limit the detail of information provided on clinicaltrials.gov (e.g. exclusionary criteria)	•May attract subjects who are more interested in potential benefits than generating income. •Will provide some protection against subjects who wish to deceive researchers by eliminating the “study guide” they use before screening.
Payment	•Limit payments in studies with a high vulnerability to enrolling professional subjects (e.g., clinical trial of narcotic pain medication). •Set a low payment amount for the initial screening visit. •Withhold payment for screening if the subject reports a behavior or health condition that should have excluded them at the time of telephone screening.	•May help to limit the enrollment of subjects who are motivated solely by payments. •May deter subjects looking for a one-time payment. •Prevents slowing of recruitment and protects against repeated costly one-session screen failures.
Telephone screening	•Construct a telephone screening that disguises the criteria for entry. •Use non-leading questions that do not reveal the entrance criteria. •Ask all screening questions even after the point that it is known that the subject will be excluded. •Develop several versions of the telephone screening.	•Can help reduce the risk of professional subjects passing a screening interview by studying the questions. •Will make it harder for subjects to study the phone screening process and determine what the “correct” answers are.
Baseline screening	•Obtain consent to review the subject's clinical records at baseline. •Include objective measures to assess other inclusion and exclusion criteria. (e.g. to determine drug use, perform a urine drug screen prior to randomization)	•May decrease concealment or fabrication of information; deception will likely be revealed when the researchers review the clinical record. •May decrease the likelihood of the use of deception during the screening.
Assessing subject motivation	•Use some degree of clinical judgment when interacting with subjects during screening. •Train staff to recognize when subjects ask payment questions more frequently, in more detail, or with greater importance.	•May help to identify subjects whose motivation is to generate income.
Attending to data inconsistencies	•Use different assessments that ask the same questions in different ways. •Be aware of data inconsistencies that are signs of professional subjects attempting to use deception during screening (e.g. data that does not make sense or is an outlier relative to other subjects with the target disease)	•May provide a validity check on the consistency of data. •May help to identify when subjects are being deceptive, exaggerative, or are concealing, or fabricating information.
Subject registries	•Implement the use of subject registries, such as CTSdatabase, DUPcheck, Verified Clinical Trials, and ClinicalRSVP.	•Will help to identify possible professional subjects by seeing if they are enrolled in multiple studies simultaneously.