A Randomized Controlled Trial of Opt-In Versus Opt-Out Enrollment Into a Diabetes Behavioral Intervention

To examine the effect of an opt-out default recruitment strategy compared to a conventional opt-in strategy on enrollment and adherence to a behavioral intervention for poorly controlled diabetic patients.

Randomized controlled trial.

University of Pennsylvania primary care practices.

Participants of this trial included those with (1) age 18 to 80 years; (2) diabetes diagnosis; and (3) a measured hemoglobin A1c (HbA1c) greater than 8% in the past 12 months.

We randomized eligible patients into opt-in and opt-out arms prior to enrollment. Those in the opt-out arm received a letter stating that they were enrolled into a diabetes research study with the option to opt out, and those in the opt-in arm received a standard recruitment letter.

Main end points include enrollment rate, defined as the proportion of participants who attended the baseline visit, and adherence to daily glycemic monitoring.

We powered our study to detect a 20% difference in adherence to device usage between arms and account for a 10% attrition rate.

Of the 569 eligible participants who received a recruitment letter, 496 were randomized to the opt-in arm and 73 to the opt-out arm. Enrollment rates were 38% in the opt-out arm and 13% in the opt-in arm ( P < .001).

Opt-out defaults, where clinically appropriate, could be a useful approach for increasing the generalizability of low-risk trials testing behavioral interventions in clinical settings.