The Effect of Informative Letters on the Prescription and Receipt of Seroquel
Last registered on September 25, 2016


Trial Information
General Information
The Effect of Informative Letters on the Prescription and Receipt of Seroquel
Initial registration date
June 08, 2015
Last updated
September 25, 2016 10:22 PM EDT
Primary Investigator
Columbia University
Other Primary Investigator(s)
PI Affiliation
General Services Administration
Additional Trial Information
On going
Start date
End date
Secondary IDs
Abusive prescribing exposes patients to unnecessary health risks and results in wasteful public expenditures. This study will evaluate an innovative approach to fighting abusive prescription: sending letters to suspected inappropriate prescribers warning them that they are outliers compared to their peers and have been flagged for review. The study will target high prescribers of Seroquel (Quetiapine), an atypical antipsychotic. Using claims data, we will assess the effect of the letters on prescribing of Seroquel, receipt of Seroquel by patients, substitution behavior by prescribers and patients, and health outcomes of patients.
External Link(s)
Registration Citation
Sacarny, Adam and David Yokum. 2016. "The Effect of Informative Letters on the Prescription and Receipt of Seroquel." AEA RCT Registry. September 25.
Experimental Details
Placebo Arm: The placebo arm receives a letter unrelated to Seroquel. The placebo letter describes a new rule in Medicare that requires prescribers to enroll in Medicare
Interventional Arm: The interventional arm prescribers receive an initial informative letter (called a comparative billing report or peer activity report) followed by 2 followup informative letters at approximately 3 month intervals. The intervention is a letter that describes the Seroquel prescribing activity of the individual in comparison to a peer group of similar prescribers. It highlights the fact that the prescriber's activity is highly unlike her peers.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
The primary outcome of the study is the 30-day equivalent prescribing of Seroquel treatments over the 9 months following the initial sending of the letters. Prescribing is defined as the total "days supply" of Seroquel attributed to the prescriber, expressed in "30-day equivalents" i.e. divided by 30. This outcome and the secondary outcomes are described in greater detail in the study prespecification document.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
An analysis was conducted to identify outlier prescribers of Seroquel in the Medicare Part D events file. This analysis identified a group of prescribers, and they were then randomly allocated to a treatment or a control group. The approach is explained in more detail in the study protocol document.
Experimental Design Details
Randomization Method
Randomization done by computer (in Stata)
Randomization Unit
The prescriber
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
2,527 allocated to treatment arm
2,528 allocated to control (placebo) arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Modeling Seroquel prescribing according to the distribution of Schedule II controlled substance prescribing, we estimated a minimum detectable effect of 1.5-1.7% of the baseline mean at a sample size of N=5,000 for 1-month and 3-month prescription drug treatments and 30-day equivalents. Because we will have access to control variables like prior prescribing that will improve our statistical power, we believe these estimates are conservative.
IRB Name
Harvard Committee on the Use of Human Subjects in Research
IRB Approval Date
IRB Approval Number
IRB Name
MIT Committee on the Use of Human as Experimental Subjects
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers