Study design: A retrospective analysis of population-based hospital discharge registry from all nonfederal acute care hospitals in Washington State.
Objective: We examined the cumulative incidence of second lumbar spine operation following an initial lumbar operation for degenerative conditions. We aimed to determine if the cumulative incidence of a second lumbar spine operation decreased in the 1990s following an increase in the rate of fusion surgery and the introduction of several newer fusion technologies.
Summary of background data: Repeat lumbar spine operations are generally undesirable, implying persistent symptoms, progression of degenerative changes, or treatment complications. Improved technology is expected to improve alignment, healing, and instability, and to reduce repeat operations.
Methods: Among the patients who had an inpatient lumbar decompression or lumbar fusion surgery for degenerative spine disorders in 1990 to 1993 (n = 24,882) or in 1997 to 2000 (n = 25,209), we examined rates of subsequent lumbar spine surgery during a 4-year follow-up. We performed a Cox proportional hazards regression to compare the probability of a reoperation between the 2 cohorts, adjusting for age, sex, primary diagnosis, type of insurance, and comorbidity.
Results: Among patients who underwent surgery for lumbar degenerative disease, more than twice as many had a fusion procedure in the 1997 to 2000 cohort (19.1%) compared with the 1990 to 1993 cohort (9.4%). However, the 4-year cumulative incidence of reoperation was higher in the 1997 to 2000 cohort compared with the 1990 to 1993 cohort (14.0% vs. 12.4%; hazard ratio, 1.16; 95% confidence interval, 1.11-1.22, P < 0.001). Among fusion patients, those in the 1997 to 2000 cohort were approximately 40% more likely to undergo a reoperation within the first year when compared with fusion patients in the 1990 to 1993 cohort. There was no difference in reoperation probability beyond 1 year.
Conclusion: A higher proportion of fusion procedures and the introduction of new spinal implants between 1993 and 1997 did not reduce reoperation rates. Patients who had lumbar surgery for degenerative disease in the late 1990s were more likely to undergo a repeat operation within 4 years than patients who had surgery in the early 1990s.