Stroke after surgery for lumbar spinal stenosis: a retrospective register-based study.

Purpose: To describe the incidence of stroke in the first year after surgery for lumbar spinal stenosis (LSS).

Methods: The study included 64,179 Swedish National Spine Register (Swespine) patients who underwent surgery for LSS between 2001 and 2020. The primary outcome was the diagnosis of stroke within the first year after surgery, as documented in the Swedish Stroke Register. The incidence was quantified as the number of strokes per 1,000 surgeries within a defined period, inclusive of the incidence rate (number of strokes/100,000 person-years). An adjusted Cox regression model was used to analyse whether age, sex, smoking, or surgery with implants further increased the risk of stroke.

Results: In the first year after surgery, 426 patients (0.66%) developed a stroke. The risk of stroke was highest during the first 30 days (n=72, 0.11%). Stroke incidence was 1.1/1,000 surgeries during the first 30 days and 6.6/1,000 surgeries during the first year after surgery. The incidence rate during the initial 30 days was 1,394 strokes per 100,000 person-years, while the incidence rate during the first year was 660 strokes per 100,000 person-years. Smoking (hazard ratio [HR], 1.82; 95% confidence interval [CI], 1.31-2.52), age 65-74 years (HR, 2.65; 95% CI, 1.91-3.67), and age ≥75 years (HR, 6.04; 95% CI, 4.42-8.25) further increased the risk of stroke.

Conclusion: The incidence of stroke after LSS surgery was the highest during the first 30 days. However, the absolute number of strokes was small. The risk of stroke could be of minor concern for most of the patients even if older age and smoking were identified as risk factors.