Association Between Oral Pain Medications and Intrathecal Opioid Dose Escalation: A Retrospective Analysis

Patients treated with intrathecal therapy frequently require opioid dose increases to maintain analgesia. The kinetics of intrathecal opioid dose escalation are poorly understood. We hypothesized that antidepressant use, antiepileptic use, and lower baseline oral opioid intake prior to intrathecal pump implantation will be protective against intrathecal opioid dose escalation.

Targeted drug delivery medication doses were collected from patients who had an intrathecal pump implanted between 2007 and 2016. From a sample size of 136 patients, the association between antidepressant, antiepileptic, and oral opioid use with intrathecal dose escalation was assessed using statistical models.

Individuals using an antiepileptic had an estimated ratio of means (97.5% CI) of opioid consumption of 0.91 (97.5% CI: [0.48, 1.73], p = 0.74) at six months, 0.83 ([0.43, 1.58], p = 0.51) at 12 months, and 0.77 ([0.40, 1.45], p = 0.36) at 24 months. Patients prescribed antidepressants had an estimated ratio of means (97.5% CI) of 1.43 ([0.77, 2.65], p = 0.19) at six months, 1.41 ([0.76, 2.63], p = 0.22) at 12 months, and 1.33 ([0.70, 2.51], p = 0.31) at 24 months. In our secondary analysis of pre-implant oral opioid use, patients treated with high oral opioid doses had a similar pattern of intrathecal dose escalation when compared to patients using low doses of oral opioids.

Use of antiepileptics, antidepressants, or low oral opioid doses was not associated with attenuation of intrathecal dose escalation. Intrathecal opioid dose escalation was observed to occur similarly, regardless of baseline oral analgesics concomitantly employed.