Effectiveness of Low Dose Naltrexone in the Management of Refractory Chronic Pain in Veterans

Background and/or Objectives: Severe chronic pain is a debilitating condition disproportionately affecting veterans, often accompanied by co-morbidities such as post-traumatic stress disorder (PTSD), anxiety, and depression. Due to the ongoing opioid crisis, treatment options for chronic pain are increasingly limited. This study aims to evaluate the effectiveness of low-dose naltrexone (LDN) in managing chronic pain in patients unresponsive to conventional non-opioid medications including NSAIDs, antidepressants, and antiepileptics.

Design: Retrospective chart review conducted from April 1, 2021, to July 1, 2024.

Setting : Urban Veterans Affairs Medical Center Pain Clinic.

Participants : Twenty-six veterans diagnosed with chronic pain refractory to physical/occupational therapy and non-opioid pharmacologic treatments

Interventions: Patients were initiated on low-dose naltrexone ranging from 0.5 to 4.5 mcg (average initial dose: 3.94 mcg), with titration based on clinical response. Final doses ranged from 0.5 to 9 mcg (average: 4.05 mcg) over an average treatment duration of five months.

Main Outcome Measures: Pre- and post-treatment scores on the Defense and Veterans Pain Rating Scale (DVPRS) and the Pain, Enjoyment, and General Activity (PEG) scale were analyzed using Student’s t-tests.

Results: The most common pain complaints were fibromyalgia and low back pain (77%), with duloxetine (77%) and gabapentin (73%) being the most frequently trialed prior treatments. PTSD and major depressive disorder were the most prevalent psychiatric comorbidities. While some individuals reported subjective improvement in pain and function, statistical analysis showed no significant differences in DVPRS or PEG scores following LDN treatment.

Conclusions: Low-dose naltrexone showed variable individual responses in veterans with refractory chronic pain, but no statistically significant improvement was observed across the cohort. Further prospective studies with larger sample sizes are needed to clarify LDN's potential role in chronic pain management among veterans.