Depression, Depressionen

Treatment

Concomitant Treatments during the Acute Study

Patients were taking from zero (n = 5) to four (median = 1) antidepressant medications while receiving VNS, during the acute study. They were also taking a mean of 3.5 ± 1.7 (median = 4, range = 1‐8) other mood disorder treatments while receiving VNS, during the acute study.

To determine if the overall strength of the antidepressant treatment regimen received concomitantly during the acute study was a prognostic indicator of treatment response, a modification of the Antidepressant Resistance Rating (ARR) based on the ATHF ratings was used to calculate the Total Strength of Treatment (TST) score. The individual ATHF ratings for each mood disorder treatment that a patient was taking during the acute study were added together to obtain a TST score. For example, if a patient was taking 525 mg venlafaxine (ARR 4), 6 mg clonazepam (ARR = 0), and 2 mg risperidone (ARR = 1) during the acute study, then the TST score would equal 5. Medications (as circumstances require) were included in the calculation of the TST, if they were rated at a strength >1 on the ARR. Patients had a mean TST score of 5.8 while receiving VNS during the acute study.

VNS Treatment

All 30 patients had the stimulation parameters set at 500µsec pulse width and 20- (n = 25) or 30-Hz (n = 5) frequency for 30 sec on and 5 min off, except for one who received a 250µsec pulse width and for three others who received stimulation for 30 sec on and 3 min off. Output currents ranged from 0.25 to 3.0 mA depending on patient tolerance (median 0.75 mA)⁹. Once the stimulation parameters were set at the end of the 2-week stimulation adjustment period, no patient required Stimulation parameter adjustments during the fixed-dose stimulation period. No device malfunctions or complications were encountered.