Clinical and financial burden of spinal infections in people who inject drugs

Background: People who inject drugs (PWID) are known to be at increased risk of infectious diseases including bacterial and blood-borne viral infections. However, there is limited literature surrounding the burden of spinal infections as a complication of injecting drug use (IDU).

Aims: To quantify the clinical and financial burden of IDU-related spinal infections.

Methods: Retrospective chart review of adult PWID with spinal infections requiring hospital admission to a tertiary health service in Melbourne, Australia between 2011 and 2019.

Results: Fifty-seven PWID with 63 episodes of spinal infections were identified with a median hospital stay of 47 days (interquartile range (IQR) 16; range 4-243 days). One-third of episodes required neurosurgical intervention and 11 (17%) episodes required intensive care unit admission (range 2-17 days). Staphylococcus aureus was the most common causative pathogen, present in three-quarters of all episodes (n = 47). The median duration of antibiotic regime was 59 days (IQR 42) and longer courses were associated with known bacteraemia (P = 0.048), polymicrobial infections (P = 0.001) and active IDU (P = 0.066). Predictors of surgery include neurological symptoms at presentation (relative risk (RR) 2.6; P = 0.010), inactive IDU status (RR 3.0; P = 0.002), a diagnosis of epidural abscess (RR 4.1; P = 0.001) and spinal abscess (RR ∞; P < 0.001). Completion of planned antimicrobial therapy was reported in 51 (82%) episodes. Average expenditure per episode was A$61 577.

Conclusions: Spinal infections in PWID are an underreported serious medical complication of IDU. Although mortality is low, there is significant morbidity with prolonged admissions, large antimicrobial requirements and surgical interventions generating a substantial cost to the health system.