Clinical practice guideline recommendations for subthreshold depression in adults: A systematic review

Subthreshold depression (SD) is highly prevalent and associated with increased risk of major depressive disorder (MDD) and other adverse outcomes. Despite substantial mental healthcare needs, treatment recommendations remain dispersed across clinical practice guidelines, hindering healthcare professionals from obtaining a cross-guideline overview.

To synthesize recommendations concerning SD and identify consistencies and inconsistencies across guidelines.

Guideline-related websites and electronic databases were systematically searched. Recommendations concerning SD formed the primary narrative synthesis. Recommendations for adjacent mild MDD were synthesized separately as contextual evidence to support interpretation of treatment-recommendation patterns surrounding SD. Guideline-level methodological quality was assessed using AGREE II.

Thirteen guidelines were included. SD was rarely addressed separately and was usually grouped with mild MDD or mild-to-moderate MDD. Five guidelines described recommendation-formulation frameworks incorporating the stepped-care principle. For SD, no guideline providing recommendations on antidepressant use supported routine use or positioned antidepressants as initial treatment; when considered, their use was limited to specific circumstances. In turn, all guidelines with formal, intervention-specific management recommendations placed low-intensity psychosocial or psychological interventions or supportive care at the start of care. The contextual synthesis for mild MDD showed a predominant pattern aligned with the overall SD pattern, although minority patterns included antidepressants as standard options or more psychotherapy options requiring trained professionals. The SD and predominant mild-MDD patterns persisted in quality-restricted analyses, while the minority antidepressant pattern for mild MDD was no longer observed.

For SD, the primary synthesis identified a coherent pattern of low-intensity initial management rather than routine antidepressant use.