Introduction:
It is well documented that opioid usage leads to increased mortality and morbidity and that certain patients may develop opioid addiction. At the same time, the clinical outcome of spinal cord stimulation (SCS) shows very large individual variation: Some patients experience almost complete pain relief, while others have no beneficial effect at all and may end up being explanted. Recently published data shows opioid consumption prior to initiation of SCS may be associated with an unfavorable treatment outcome. We investigated whether opioid usage prior to initiation of SCS was associated with:
1) Risk of permanent explantation as a proxy of treatment failure.
2) Latest rating on Patients’ Global Impression of Change (PGIC) scale.

Methods:
We used data from the Neurizon Neuromodulation Database containing detailed records of patients implanted with a device for SCS at Aarhus, Odense or Aalborg University Hospital, Denmark. From the database records we identified patients with a preimplantation medicine registration and subsequently their current treatment status (active stimulation/permanently explanted) and latest PGIC rating.
Patients were grouped according to preimplantation opioid use (Y/N) and oral morphine equivalent values (OME) were calculated for opioid users. The relationships between preimplantation opioid use, current treatment status and latest PGIC rating were evaluated with chi^2-tests. Associations between preimplantation OME values, current treatment status and latest PGIC rating were assessed by a t-test and a one-way ANOVA of log transformed data, respectively.

Results:
A total of 248 patients had a preimplantation medicine registration – all of these had a registration of currents treatment status and 190 patients had a PGIC rating. The presence of opioid usage (Y/N) prior to initiation of SCS was not associated with current treatment status (p-value =0.58) or latest PGIC rating (p-value = 0.39). Among opioid users median preimplantation OME values did not differ between groups of current treatment status (p-value = 0.20) or PGIC rating (p-value = 0.48).

Conclusion:
The presence of opioid usage (Y/N) prior to implantation with a device for SCS was not associated with risk of permanent explantation or latest PGIC rating.
Among patients using opioids prior to implantation, the dosage of opioids expressed in terms of OME values was not associated with risk of being permanently explanted or latest PGIC rating.