Surgical trends and regional variation in Danish patients diagnosed with lumbar spinal stenosis between 2002 and 2018: a retrospective registry-based study of 83,783 patients

Background Lumbar spinal stenosis (LSS) is the most common reason for spine surgery in older people. However, surgery rates vary widely both internationally and nationally. This study compared patient and sociodemographic characteristics, geographical location and comorbidity between surgically and non-surgically treated Danish patients diagnosed with LSS from 2002 to 2018 and described variations over time. Methods Diagnostic ICD-10 codes identifying patients with LSS and surgical procedure codes for decompression with or without fusion were retrieved from the Danish National Patient Register. Patients ≥ 18 years who had been admitted to private or public hospitals in Denmark between 2002 and 2018 were included. Data on age, sex, income, retirement status, geographical region and comorbidity were extracted. A multivariable logistic regression model was used to calculate the relative risk for surgically versus non-surgically treated LSS patients using the total population and subsequently divided into three time periods. Variations over time were displayed graphically. Results A total of 83,783 unique patients with an LSS diagnosis were identified, and of these, 38,362 (46%) underwent decompression surgery. Compared to those who did not receive surgery, the surgically treated patients were more likely to be aged 65–74 years, were less likely to have comorbidities, had higher income and were more likely to reside in the northern part of Denmark. Patients aged 65–74 years remained more likely to receive surgery over time, although the difference between age groups eventually diminished, as older patients (aged ≥ 75) were increasingly more likely to undergo surgery. Large variations and differences in the relative risk of surgery were observed within and between the geographical regions. The likelihood of receiving surgery varied up to threefold between regions. Conclusion Danish patients with LSS who receive surgery differ in a number of respects from those not receiving surgery. Patients aged 65 to 74 years were more likely to receive surgery than other age groups, and LSS surgical patients were healthier, more often retired and had higher incomes than those not undergoing surgery. There were considerable variations in the relative risk of surgery between and within geographical regions.