Table 1:

Explanation of covariates

Trial Characteristics
Number of Adequate Medication Trials (AMTs) Aligned with PTSD Checklist (PCL) Measurement	Adequate trials of fluoxetine, paroxetine, sertraline, topiramate, or venlafaxine aligned with PCL measurement that each patient contributed to the outcomes analysis. Trials of different agents could overlap or dovetail, but we required a one-year gap in prescriptions to count as a new trial of the same agent.
PCL Severity and Timing	Baseline PCL score, number of days between first available PTSD diagnosis and baseline PCL, number of days from baseline PCL to follow-up PCL for each trial included in the outcomes analysis.
Number of Prior AMTs	AMTs with or without PCL measurement between 1999 and the start of each trial included in the outcomes analysis.
Number of Prior Adequate Prolonged Exposure (PE) or Cognitive Processing Therapy (CPT) Trialsa	Episodes where patients received ≥8 sessions PE or CPT over the course of one year between 1999 and the start of each medication trial included in the outcomes analysis.
Concurrent Treatments	Additional treatments received at the same time as an AMT associated with PCL measurement
Psychotherapy	Categorical receipt and number of sessions
PEa	Individual only
CPTa	Group and individual
Other psychotherapy	Group and individual
Medications	Categorical receipt of other antidepressants, sedative hypnotics, opioids, atypical antipsychotics, prazosin, medications for alcohol abuse including naltrexone or acamprosate, and opioid replacement medications including buprenorphine or methadone prescribed within the context of methadone treatment clinic
Primary Prescribing Clinician Characteristics	Clinician who wrote the plurality of each patient’s psychotropic prescriptions during the 12-week treatment period
Age	Continuous
Gender	Categorical male or female
Professional background	e.g. psychiatrist or nurse practitioner
Percent of time spent seeing PTSD patients in various settings	e.g. specialized PTSD clinic or primary care clinic, based on assumption that prescribing clinicians who spend a higher percentage of their time in specialized PTSD settings may bring increased knowledge and experience in treating PTSD, even when seeing patients in non-specialized settings.
Baseline Patient Characteristics	Demographics, military service characteristics
VA Health Service use Characteristics	Assessed in the year preceding baseline PCL.
Outpatient visits	e.g. visits to specialized PTSD clinics or to primary care clinics
Acute psychiatric care use	e.g. emergency department visits for psychiatric indications or psychiatric hospitalizations
Residential treatment	e.g. stays in residential PTSD or substance abuse programs
Psychiatric Comorbidities	Psychiatric diagnoses in the two years preceding the baseline PCL measurement

^aEBP use was measured with a natural language processing algorithm that classifies psychotherapy notes in individual and group delivery formats.¹⁴