Frequency of therapeutic drug monitoring in inpatient precision depression care and duration of hospitalization.

Inclusion criteria were a hospital stay ≥7 days and a first therapeutic drug monitoring request at admission.

The upper effective threshold was approximated at 1.3/week.

Higher therapeutic drug monitoring frequency was associated with more therapy adjustments within 7 days after therapeutic drug monitoring, including dose adaptations (p = 3.07*10 - ¹⁶) and drug initiation/discontinuation (p = 6.70*10 -6 ).