Primary 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.