Maintenance Inhaled Corticosteroid Use is Associated With Increased Revision Risk in Asthmatic Patients Undergoing Lumbar Fusion

Study Design: Retrospective cohort study. Objectives: To compare all-cause revision rates after lumbar fusion among asthmatic patients receiving maintenance inhaled corticosteroid (ICS) therapy, asthmatic patients without maintenance ICS, and asthma-free controls without ICS exposure. Methods: Three cohorts of patients undergoing lumbar fusion were identified from a real-world health records database: (1) asthmatic patients with maintenance ICS therapy, (2) asthmatic patients without ICS therapy, and (3) asthma-free controls. Pairwise 1:1 propensity-score matching was performed to control for baseline differences in comorbidities, including known osteoporosis and systemic steroid exposure. All-cause revision rates were compared between cohorts at two- and five-years post-fusion using Chi-square tests and Kaplan-Meier analyses. Results: Asthmatic patients on maintenance ICS were significantly more likely than asthmatic patients without ICS to undergo revision at 2 (P < 0.001, OR = 3.11, 95%CI = 2.25-4.31) and 5 (P < 0.001, OR = 3.16, 95%CI = 2.34-4.19) years following fusion. Asthmatic patients receiving maintenance ICS were also more likely than asthma-free controls to undergo revision at 2 (P < 0.001, OR = 3.48, 95%CI = 2.47-4.90) and 5 (P < 0.001, OR = 3.98, 95%CI = 2.92-5.42) years. Asthmatic patients without maintenance ICS had similar hazard of revision over 5 years of follow-up compared to asthma-free controls (P = 0.082, HR = 1.07; 95%CI = 0.99-1.15). Conclusions: Maintenance ICS therapy is associated with increased risk of revision following lumbar fusion in asthmatic patients. ICS use, traditionally considered low-risk, may have clinically relevant effects on lumbar fusion outcomes. Future studies are warranted to further elucidate the biological mechanisms driving revision in these patients.