Collaborative care (CC) and consultation liaison (CL) are two conceptual models aiming to improve mental healthcare in primary care. The effects of these models have not been compared in a Danish setting.

To examine the effects of CC versus CL for persons with anxiety and depression in Danish general practices (trial registration: NCT03113175 and NCT03113201).

Two randomised parallel superiority trials for anxiety disorders and depression were carried out in 2018–2019. In the CC-group, care managers collaborated with general practitioners (GPs) to provide evidence-based treatment according to structured treatment plans. They followed up and provided psychoeducation and/or cognitive–behavioural therapy. The GPs initiated pharmacological treatment if indicated, and a psychiatrist provided supervision. In the CL-group, the intervention consisted of the GP's usual treatment. However, the psychiatrist and care manager could be consulted. Primary outcomes were depression symptoms (Beck Depression Inventory-II, BDI-II) in the depression trial and anxiety symptoms (Beck Anxiety Inventory, BAI) in the anxiety trial at 6-month follow-up.

In total, 302 participants with anxiety disorders and 389 participants with depression were included. A significant difference in BDI-II score was found in the depression trial, with larger symptom reductions in the CC-group (CC: 12.7, 95% CI 11.4–14.0; CL: 17.5, 95% CI 16.2–18.9; Cohen's d = −0.50, P ≤ 0.001). There was a significant difference in BAI in the anxiety trial (CC: 14.9, 95% CI 13.5–16.3; CL: 17.9, 95% CI 16.5–19.3; Cohen's d = −0.34, P ≤ 0.001), with larger symptom reductions in the CC-group.

Collaborative care was an effective model to improve outcomes for persons with depression and anxiety disorders.

Substance use disorder is highly prevalent in people with psychiatric disorders, and known to impede the psychiatric treatment. Some studies show increased rates of service use, while others show a decrease. These conflicting results are further hampered by a lack of large-scale studies. The aim of this study was to investigate the association between substance use disorder and psychiatric service use in psychiatric patients.

The study was a prospective registry-based cohort study including patients with severe mental illness. The primary outcome was the number of hospitalisations, bed days and the number of psychiatric emergency department contacts. The association was calculated with incidence rate ratio with 95% confidence intervals.

The study included all psychiatric patients born since 1955. In total, 21 558 patients with schizophrenia (47.54% with substance use disorder), 80 778 patients with depression (28.78% with substance use disorder), 10 560 patients with bipolar affective disorder (40.08% with substance use disorder) and 69 252 patients with a personality disorder (39.18% with substance use disorder) were included. Patients with comorbid substance use disorder had significantly increased rates of hospitalisations, bed days and psychiatric emergency department contacts (p < 0.001) for the majority of the included substances, compared with patients without such disorders.

Substance use disorder was associated with an increased number of hospitalisations, bed days and increased number of psychiatric emergency department contacts for the majority of the included substances.