Gender Differences in Transcranial Magnetic Stimulation Treatment Outcomes for Major Depressive Disorder: A Single Institution Experience

these modalities fit in the treatment of MDD.We report on one approach of crossing poor responders of TMS to Ketamine IV. Methods: From 2016 to early 2020 we treated nine patients with suboptimal results with a full course (36) TMS therapy treatments. Five of the nine patients had less than a 25% response rate, and four had a greater than 50% response rate, with none reaching remission. Each patient was tracked using the PHQ-9 instrument during TMS and K-IV. The nine patients entered a course of K-IV treatments, with the average number of treatments being 5.75. Results: After K-IV treatments, 4 of the nine patients had a significant responsewith a score of 10, 7, and 6. Each of these patients had no response to the previous TMS course. The remainingfivepatientswho crossedover to K-IV had no improvement. No adverse events were reported. Conclusions: We saw four of the nine patients that had failed to gain improvement from TMS therapy gain significant improvement with 6 K-IV treatments. Although this is a small sample size, we are optimistic about continuing to offer Ketamine IV for those with TRD who are not gaining symptoms improvement with a full course of TMS. Consider that over 1/3 of those crossed to K-IV are achieving significant improvement responses who had previous failed to benefit from multiple courses of medication and a full course of TMS therapy. Discussion: Choosing between TMS therapy and K-IV for those with treatment-resistant depression is less optimal then desired. Primary criteria include patient distance to the office, financial / insurance solvency, and a history of substance abuse. A portion of the population in Billings, Montana, consists of a rural community. For those struggling with TRD and at a considerable distance from the office (over 100 miles is not unusual) Ketamine IV maybe a better solution for it requires only six office visits compared to over 30 for TMS treatments. Another challenge in selecting the right treatment is the out-of-pocket expense for Ketamine IV, which is not covered by insurance. This cost is typically no less than double the price of a patient deductible who has TMS therapy covered by their insurance. Lastly, we see those who have a history of substance abuse to be contraindicated for Ketamine IV and primary candidates for TMS therapy. In addition to the small sample size, we do find frommanywho are treated with Ketamine IV a response several weeks beyond the final treatment. Future analysis needs to include better post treatment follow-up. Future research should also include an arm for patients not benefiting from Ketamine IV as the first interventional treatment to cross-over to TMS therapy.