Introduction:  Due to the opioid epidemic in the United States, there is increasing awareness of prescribing practices and the potential for unused prescriptions to contribute to the ongoing crisis.  Spine surgery is associated with substantial postoperative analgesia requirements and opioid consumption. However, there is a lack of understanding of postoperative opioid consumption and standardized prescribing practices with respect to the type of spine surgery (i.e. anterior cervical and lumbar decompression/fusion).  The primary objective was to determine postoperative 90-day opioid consumption in patients undergoing elective spine surgery.  The secondary objectives were to identify differences in opioid consumption between spine surgery subgroups and to determine the distribution of opioids consumed to achieve sufficient postoperative pain control up to the 90^th percentile of patients within the 90-day period.

Methods: This is a prospective observational cohort study at a multi-surgeon, single center.  Consecutive, adult (>18 years) patients undergoing elective spine surgery were eligible for inclusion.  Surgeries were divided into subgroups: anterior cervical, posterior lumbar decompression, and short-segment (< 4 levels) circumferential fusion. During the 90-day postoperative period, prescribed MMEs were calculated from opioid prescriptions and consumed MMEs were calculated from pill counts. Preoperative opioid status was recorded as: opioid tolerant (opioid use within 3 months of surgery) or opioid naïve (no opioid use within 3 months of surgery). Prescribed and consumed 90-day MMEs were compared between the three surgical subgroups. Consumed MME distributions were analyzed by the preoperative opioid status (tolerant or naïve) to identify the 50^th, 75^th, and 90^th percentiles within each surgical subgroup.

Results: A total of 117 patients with a mean age of 52 years-old (48.7% male) completed the 90-day follow-up. Across all surgical subgroups (n=48, cervical; n=28, lumbar decompression; n=41, lumbar fusion), 41.9% were opioid tolerant. The mean 90-day MMEs prescribed was 2188.4 and consumed was 1648.5, giving a difference of 540.0 MMEs not consumed. The mean difference in 90-day MMEs prescribed and consumed was significantly different between the surgical subgroups: 388.4 cervical, 375.6 lumbar decompression, and 839.7 lumbar fusion (p=0.002). The percentage of unused opioids at 90-days was on average: 22.5% cervical, 33.7% lumbar decompression, and 23.7% lumbar fusion. The 90^th percentile for MMEs consumed in each subgroup were: 660 opioid naïve cervical, 6728 opioid tolerant cervical, 300 opioid naïve lumbar decompression, 2490 opioid tolerant lumbar decompression, 4995 opioid naïve lumbar fusion, and 7710 opioid tolerant lumbar fusion.

Discussion: This study showed that across all surgical subgroups, greater than 20-30% of total MMEs prescribed were unused at 90 days. This suggests that there is a need for the development and adoption of standardized prescribing practices for postoperative opiates. While the results of this study suggest that the number of MMEs prescribed can be reduced to mitigate the effects of leftover pills, larger studies with multiple high-volume centers could help in standardizing opioid prescribing practices across elective spine surgeries.