Poster Number-57 - Evaluation of Ketamine Infusions in Chronic Pain Patients at TVHS

Evaluation of Ketamine Infusions in Chronic Pain Patients at TVHS

Purpose:

Due to the high prevalence of chronic pain conditions in the Veteran population and the recent emphasis on finding alternatives to commonly misused pain medications, the VA is an ideal location to assess the use and impact of ketamine infusions for those suffering with chronic pain conditions. As one of the most well-established ketamine infusion programs for pain in the VA system this is an opportunity to investigate gaps in current literature related to the long term effectiveness of ketamine infusions for chronic pain conditions. The primary objective of this project was to evaluate the efficacy of ketamine infusions for chronic pain long-term (12-15 months), overall and by pain category (neuropathic, spinal discogenic, and musculoskeletal pain. The secondary objectives of this project were to assess dropout rates due to adverse events and the effects of benzodiazepine pre-medication on dropout rates, daily morphine milliequivalents – before infusion vs. long-term ( 12 – 15 months), and mental health comorbidities. 

Methods:

This was a single-center, retrospective, observational cohort study conducted at the VA Tennessee Valley Healthcare System (TVHS).  Veterans had to be diagnosed with chronic pain (lasting at least three months or longer) and have received ketamine infusions for chronic pain. Initial data were provided through the VA data warehouse and further data were extracted via manual chart review. The primary endpoints  were measured using the Numerical Pain Rating Scale (NRS), before infusion (baseline) and at intervals (about every 3 months) until the primary end point of 12-15 months. The secondary endpoints were measured as (n/%) for dropout rates, MEDD change as (%). Data were then analyzed using appropriate statistical methods, (Wilcoxon paired rank sign and Fischer's exact) for determining statistical significance for respective endpoints. Demographic data were analyzed utilizing descriptive statistics.

Results:

The primary endpoint of ketamine infusions was shown to reduce pain long-term (12-15months) which was statistically significant, with a (-28.5% reduction in pain overall, for neuropathic pain and musculoskeletal pain categories) and Spinal discogenic pathology had a clinically significant reduction in pain (-39%, p=0.0152) at the primary endpoint of 12-15months after ketamine induction. Additionally, with respect to secondary endpoints the dropout rate between those pre-treated and those not with benzodiazepines was not statistically significant (24.3% vs. 29.7%, p = 0.4730). The mean MEDD was 76.88mg and decreased to 26.18mg, a 50.1% reduction. The effect of benzodiazepine pre-medication also had an impact on MEDD reduction compared to those who were not pre-medicated. The impact was statistically significant with a mean reduction of 75.6% vs. 5.2% (p = 0.0001), further showing the benefit of pre-medication in this population. 

Conclusion:

This study demonstrates the potential for ketamine infusions as a viable option for refractory chronic pain treatment long-term, however further studies need to be conducted to determine in more detail which specific pain diagnoses would benefit from ketamine infusions. Furthermore, while pre-medication with benzodiazepines does not have a statistically significant effect on dropout rates, it did have a significant effect on rate of adverse events and MEDD reduction over the course of treatment. Lastly, as previously demonstrated ketamine was shown to attenuate opioid use, which is demonstrated by the reduction of MEDD before and after ketamine infusions in this study. 

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