The Effect of Informative Letters on the Prescription and Receipt of Schedule II Controlled Substances
Last registered on May 03, 2017


Trial Information
General Information
The Effect of Informative Letters on the Prescription and Receipt of Schedule II Controlled Substances
Initial registration date
October 06, 2014
Last updated
May 03, 2017 2:48 PM EDT
Primary Investigator
Other Primary Investigator(s)
PI Affiliation
Harvard University
PI Affiliation
General Services Administration
Additional Trial Information
Start date
End date
Secondary IDs
Fraud and waste is estimated to cost the American health care system nearly $200 billion each year, and the public Medicare and Medicaid programs about $60 billion each year. This study will evaluate a new method for fighting fraud: mailing informative letters to outlier providers to notify them of their aberrant behavior. These letters are targeted at high prescribers of schedule II controlled substances in Medicare Part D. We will look at the effects of these letters on the behavior of providers and their patients. These effects are of substantial policy interest as they suggest how to best design anti-fraud policies. They are also of academic interest, shedding light on the behavior of physicians and their patients.
External Link(s)
Registration Citation
Finkelstein, Amy, Adam Sacarny and David Yokum. 2017. "The Effect of Informative Letters on the Prescription and Receipt of Schedule II Controlled Substances." AEA RCT Registry. May 03.
Experimental Details
A letter to outlier prescribers of schedule II controlled substances explaining that their prescribing behavior is highly unlike their peers.
Intervention Start Date
Intervention End Date
Outcomes (end points)
The primary outcome of the study is the effect of the letters on the prescribing of schedule II controlled substances over the 3 months following the initial sending of the letters. Prescribing is defined as the total “days supply” of schedule II controlled substances attributed to the prescriber, expressed in “30-day equivalents” i.e. divided by 30. We consider additional outcomes as well. Through these additional analyses, we hope to understand the totality of the effects of the letters. The secondary analysis for prescribers includes explorations of effect heterogeneity, quantile treatment effects, substitution toward other substances, and peer effects. We also conduct analyses looking at a cohort of patients who were treated by the prescribers prior to the sending of the letters. We will assign these patients to treatment and control groups based on whether their attributed prescriber was a treatment or control prescriber and study the total receipt of controlled substances by patients, heterogeneity in treatment effects, substitution toward other substances, and health outcomes.
Outcomes (explanation)
Experimental Design
Experimental Design
An analysis was conducted to identify outlier prescribers of Schedule II controlled substances in the Medicare Part D. This analysis identified a group of prescribers, and they were then randomly allocated to a treatment or a control group.
Experimental Design Details
Randomization Method
Randomization done by computer (in Stata)
Randomization Unit
The prescriber (e.g. physician, nurse, physician assistant, etc.)
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Approximately 1500 prescribers
Sample size: planned number of observations
Approximately 1500 prescribers
Sample size (or number of clusters) by treatment arms
Approximately 750 providers in the control arm and 750 providers in the treatment arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We constructed a sample of outlier prescribers that replicated the method used in the study but was built from a more limited dataset. Using these prescribers we estimated that at a significance level of 5% and a power of 80%, we could detect a change in the number of schedule II prescription drug events of 136.9 (baseline mean level: 1,556.7; standard deviation: 1,231.2; effect as a share of baseline mean: 8.8%) and a change in the dollar value of schedule II prescriptions of $34,069 (baseline mean level: $217,204; standard deviation: $239,759; effect as a share of baseline mean: 15.7%). Since we will have access to richer data with better control variables, we believe that 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?
Intervention Completion Date
March 11, 2015, 12:00 AM +00:00
Is data collection complete?
Data Collection Completion Date
August 14, 2015, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
1518 prescribers
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
1518 prescribers
Final Sample Size (or Number of Clusters) by Treatment Arms
760 prescribers treatment 758 prescribers control
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers
Inappropriate prescribing is a rising threat to the health of Medicare beneficiaries and a drain on Medicare’s finances. In this study we used a randomized controlled trial approach to evaluate a low-cost, light-touch intervention aimed at reducing the inappropriate provision of Schedule II controlled substances in the Medicare Part D program. Potential overprescribers were sent a letter explaining that their practice patterns were highly unlike those of their peers. Using rich administrative data, we were unable to detect an effect of these letters on prescribing. We describe ongoing efforts to build on this null result with alternative interventions. Learning about the potential of light-touch interventions, both effective and ineffective, will help produce a better toolkit for policy makers to improve the value and safety of health care.
Sacarny, Adam, David Yokum, Amy Finkelstein, and Shantanu Agrawal. "Medicare Letters To Curb Overprescribing Of Controlled Substances Had No Detectable Effect On Providers." Health Affairs. 2016; 35(3); 471-479. doi:10.1377/hlthaff.2015.1025