Impact of detailed informed consent on research subjects' participation: a prospective, randomized trial

Abstract

This study was undertaken to measure potential research subjects' participation in a survey research design, based on level and type of informed consent required before enrollment. In this prospective, randomized trial, 300 eligible Emergency Department participants were randomized to one of three groups: verbal consent (n = 100), limited written consent (n = 100), and detailed written consent with signature (n = 100). The consent was related to a self-administered patient satisfaction survey. The primary outcome was level of participation, where participation was categorized as full, limited, or refusal. Ninety-five percent confidence intervals (CI) constructed about proportions were used to assess differences in participation rates between the three consent groups. Among 300 participants, no demographic differences were found between groups for age or gender. Participants who were randomized to complete the detailed written consent had a significantly lower rate of full participation (72%) when compared to those randomized to verbal consent (85%; mean difference between groups 13%, 95% CI 2% to 24%) and to those with limited written consent (84%; mean difference between groups 12%, 95% CI 1% to 23%). Participants randomized to detailed written consent also had a significantly higher refusal rate (23%) when compared to those in the limited written group (12%; mean difference between groups -11%, 95% CI -21% to -1%). The length and type of informed consent required affected potential research subject participation in a survey research design. Participants who were asked to sign a detailed written informed consent document had a lower rate of participation compared to those with verbal or limited written consent.