Variations in general practitioners’ referrals to low-value MRI examinations in Norway: A nationwide register-based study

BACKGROUND: Large variations in diagnostic imaging use raise concerns about low-value care, inequity, and inefficient use of resources. Magnetic resonance imaging (MRI) of the head, lumbosacral spine, and knee has been identified as potentially low-value examinations in several clinical contexts. OBJECTIVES: To examine variation in general practitioners' referrals to low-value MRI examinations in Norway and assess whether differences are associated with GP and practice characteristics. METHODS: Using national registry data, we linked patients' completed MRI examinations to their regular GP and calculated GP-specific MRI rates per 1000 listed patients. We classified GPs into deciles and compared the characteristics of GPs in the highest (High-10) and lowest (Low-10) referral deciles. We examined predictors of variation using pooled OLS regression models with year fixed effects and GP-clustered standard errors. RESULTS: GPs in the top referring decile (High-10) referred patients for potentially low-value MRI examinations at three times the rate of those in the lowest referring decile (Low-10). Experienced (specialist-certified) GPs referred approximately 2.7 fewer examinations per 1000 listed patients per year than less experienced GPs (non-specialists). Shorter consultation times, higher consultation frequency and higher hourly fee income were all associated with higher MRI use - with the strongest association for private MRI. A higher patient disease burden was associated with more total examination, but fewer private examinations per 1000 listed patients per year. CONCLUSION: Referral rates varied markedly between GPs. Specialist-certified GPs had lower rates than non-specialists, and higher activity levels and income from fees were associated with higher referral rates - particularly to private providers.