Randomized controlled trials (RCTs) have eligibility criteria for the inclusion of participants. Ideally, the RCT sample would be representative for the patient population that will use the drug under investigation. However, external validity may be at stake when applying too many or too restrictive eligibility criteria. The current two-part study examined (1) the currently applied eligibility criteria in Phase II and III RCTs examining sleep medication; (2) how these criteria match with the insomnia population as a whole; and (3) how inclusion rates can be changed by an adaptation of these criteria. In the first study, insomnia RCTs were screened at www.clinicaltrials.gov, and relevant eligibility criteria were identified. The second study comprised a survey among self-reported insomnia patients. It was determined to what extent RCT eligibility criteria match the characteristics of this patient population. Of the n
= 519 patients that completed the survey only n
= 2 (0.4%) met all eligibility criteria of current RCTs. RCT enrolment criteria are not representative for the insomnia patient population as a whole. Being less rigorous in applying upper or lower criteria limits results in a significant increase in the number of eligible patients, and increases the representativeness of RCTs for the insomnia patient population as a whole. The current analysis demonstrates that is important to thoroughly reconsider the use eligibility criteria and their inclusion ranges, and to have a theoretical basis for using them.
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