eTable 1. Documentation of interventions/treatments.

Physician questionnaire
Procedure/treatment on reference date	● Nothing done/no intervention needed ● Initially no action, repeat visit (corresponding to active waiting) ● Referral for specialist care (psychiatrist, psychotherapist, inpatient, other) ●Treatment (discussion/consultation, psychotherapy, medication)
Existing ongoing treatments	● Psychiatric/drug treatment – Ongoing treatment by psychiatrist – Inpatient treatment – Antidepressants – Other medication ● Psychotherapy – Ongoing – Inpatient ● Discussion/consultation ● Other (free description)
Type of medication (prescribed by primary care physician or, in context of ongoing treatment, by specialist)	● Antidepressants – Tri-/tetracyclics (TCA) – Selective serotonin reuptake inhibitors (SSRI) – Noradrenergic and specific serotonergic antidepressants (NaSSA) – Selective serotonin–norepinephrine reuptake inhibitors (SSNRI) ● Other medications ● Hypnotics/sedatives ● Neuroleptics/antipsychotics ● Phytotherapeutics ● Other (free description)
Patient questionnaire
Current treatments	● Medication ● Discussion ● Psychotherapy ● Other (free description)
Categorization for assessment of guideline adherence
(1) Psychotherapy	● Psychotherapeutic treatment by primary care physician on reference date ● Referral to psychotherapist or for inpatient care initiated by physician or reported as ongoing ● Statement of currently ongoing psychotherapy by physician or patient
(2) Antidepressants	● Treatment on reference date or currently ongoing treatment (as stated by physician) with following substances: TCA, SSRI, NaSSA, SSNR ● Referral to psychiatrist or for inpatient care initiated by physician or reported as ongoing
(3) Other treatments	● Consultation, discussions (statements by physician and patient regarding reference date and ongoing treatments) ● Treatment with hypnotics/sedatives, neuroleptics/antipsychotics, and/or phytotherapeutics (statements by physician regarding reference date and ongoing treatments) or unspecific information about drug treatment (statement by patient) ● Treatments other than those mentioned above (statements by physician and patient)
(4) No treatment	● None of the interventions in categories (1), (2), and (3) mentioned by either physician or patient