The influence of rheumatoid arthritis on higher reoperation rate over time following lumbar spinal fusion -A nationwide cohort study-

This study aimed to compare the rates of reoperation over time following first lumbar fusion between rheumatoid arthritis (RA) patients and non-RA patients. This study was conducted using Korean Health Insurance Review and Assessment (HIRA) data. We identified the RA group as 2,239 patients who underwent first lumbar fusion with RA and the control group as 11,195 patients without RA. This reflects a ratio of 1:5, and participants were matched by sex, age, and index surgery date. Index dates were between 2012 and 2013. When comparing the rate of patients undergoing reoperation, the adjusted HR was 1.31(95%CI: 1.10-1.6) in the RA group (p=0.002). In terms of the three-time intervals, the values in the time frames <3 months and 3months-1year were not statistically significant. However, after 1year post-surgery, there was a higher risk of reoperation in the RA group, as demonstrated by the Kaplan-Meier cumulative event analysis. This higher risk of reoperation continued to increase through 5years of follow-up, after which it was stable until the last follow-up at 7years. This population-based cohort study showed that the RA patients had a 1.31times higher risk of reoperation following lumbar fusion than did the controls. This difference was more pronounced after 1year post-surgery.