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The Spine Blog

Friday, October 4, 2019

The cost of drug abuse related spinal infections

The toll of the opioid crisis has been well-documented in the scientific and lay press. The public has less understanding of some of the specific complications related to injection drug use such as spinal infection. In order to better understand spinal infections related to drug use, Dr. Alhourani and colleagues analyzed the MarketScan database from 2000-2016 to evaluate the costs and complications related to spinal infection in three distinct groups:  post-surgical patients, patients with a diagnosis of drug abuse, and patients without prior spine surgery or drug abuse (referred to as the control group). The codes for spinal infection included diskitis, osteomyelitis, and epidural abscess. Based on ICD coding, they identified approximately 44,000 patients with a diagnosis of spinal infection. Of these, 16% had undergone prior spinal surgery, 4% had a diagnosis of drug abuse, and 80% were in the control group. The drug abuse group was significantly younger (47 vs. 55 control vs. 54 post-surgical), more likely to have Medicaid (67% vs. 24% control vs. 15% post-surgical), and more likely to have an Elixhauser comorbidity index of 3 or higher (40% vs. 24% control vs. 20% post-surgical). The drug abuse and control groups had a similar rate of surgery at the index hospitalization (9% vs. 10%) but a lower rate than the post-surgical group (17%). The drug abuse group also had the highest inpatient complication rate. Costs for the drug abuse group were actually somewhat lower for the index hospitalization and first month following discharge compared to the other two groups. However, over the first year, the drug abuse group had the highest rate of readmission (66% vs. 46% control vs. 42% post-surgical) and highest overall cost ($44K vs. $37K control vs. $38K post-surgical).

This study did a nice job of using administrative billing data to demonstrate the costs associated with spinal infections in patients with a diagnosis of drug abuse. While the initial costs are similar to or less than the control group, over the course of the first year the costs for the drug abuse group substantially exceeded the costs for the patients without drug abuse. The limitations of studies based on administrative billing data always need to be considered. In this case, it is unclear how accurately the drug abuse code is used. It likely varies across different hospitals, with some coding for it frequently and others probably not using it. Many drug-abusing patients probably did not get coded as such. This would result in the control group containing drug abusers, which would dilute any differences between the two groups. Additionally, the drug abuse code is not specific for the use of intravenous drugs, which is the main drug-related risk factor for spinal infection. It would have been interesting if the authors could have looked at the proportion of spinal infections in drug abusers over time to see if this correlated to the increase in IV drug use over the period of study. This paper highlights the high cost to society associated with treating spinal infections, especially those related to drug abuse. As demonstrated by the high costs that continued to accrue over the year following initial diagnosis of the spinal infection, medical problems related to drug abuse do not go away after treating the infection. The only way to decrease the continued burden on the healthcare system is to treat the underlying drug abuse disorder, and this is rarely done in combination with treating the infection. Treating spinal infection is apparently easier than treating drug addiction.

Please read Dr. Alhourani's article on this topic in the October 15 issue. Have you seen more spinal infections related to drug abuse over the past decade? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor