Geographical variation in orthopedic procedures in Norway: cross-sectional population-based study

Background: Standardized surgery rates for common orthopedic procedures vary across geographical areas in Norway. We explored whether area-level factors related to demand and supply in publicly funded healthcare are associated with geographical variation in surgery rates for six common orthopedic procedures. Methods: The present study is a cross-sectional population-based study of hospital referral areas in Norway. We included adult admissions for arthroscopy for degenerative knee disease, arthroplasty for osteoarthritis of the knee and hip, surgical treatment for hip fracture, and decompression with/without fusion for lumbar disk herniation and lumbar spinal stenosis in 2012–2016. Variation in age and sex standardized rates was estimated using extremal quotients, coefficients of variation, and systematic components of variation (SCV). Associations between surgery rates and the socioeconomic factors urbanity, unemployment, low-income, high level of education, mortality, and number of surgeons and hospitals were explored with linear regression analyses. Results: Knee arthroscopy showed highest level of variation (SCV 10.3) and decreased in numbers. Variation was considerable for spine surgery (SCV 3.8–4.9), moderate to low for arthroplasty procedures (SCV 0.8–2.6), and small for hip fracture surgery (SCV 0.2). Higher rates of knee arthroscopy were associated with more orthopedic surgeons (adjusted coefficient 24.8, 95% confidence interval (CI): 2.7–47.0), and less urban population (adjusted coefficient −13.3, 95% CI: −25.4 to −1.2). Higher spine surgery rates were associated with more hospitals (adjusted coefficient 22.4, 95% CI: 4.6–40.2), more urban population (adjusted coefficient 2.1, 95% CI: 0.4–3.8), and lower mortality (adjusted coefficient −192.6, 95% CI: −384.2 to −1.1). Rates for arthroplasty and hip fracture surgery were not associated with supply/demand factors included. Conclusions: Arthroscopy for degenerative knee disease decreased in line with guidelines, but showed high variation of surgery rates. Socioeconomic factors included in this study did not explain geographical variation in orthopedic surgery.