Abstract

Study design. Retrospective cohort study using medical claims data. Objective. To document the extent of geographic variation in utilization of magnetic resonance imaging (MRI) for working-age patients early in the course of acute, disabling low back pain (LBP); to identify potential factors associated with the most extreme variations. Summary of Background Data. Although guidelines discourage MRI in acute uncomplicated LBP, this practice is highly prevalent. Geographic variation in radiologic testing is common, and may indicate problems with access or quality of care, yet this has not been studied in working-age patients with LBP (a frequent cause for acute care visits). Methods. All cases of acute, disabling LBP with onset between 1/1/2002 and 12/31/2007 were selected from a large workers' compensation data source. Detailed information from medical bills was used to identify persons who received early MRI (within 30 days of onset), classify cases by LBP severity, and exclude those with concurrent injuries or diseases, and/or prior LBP disability. Individual predictors included age, gender, job tenure, and industry. State-level predictors included economic, physician supply and practice variables, workers compensation system features, and MRI testing location. Generalized linear mixed models were constructed to evaluate within-and between-state variability, selecting the six highest and six lowest MRI utilization states. Results. State rates of early MRI scanning varied from 6.0% to 58.4%. In the 12 selected most extreme states, non-hospital MRI sites and lower state median income were associated with higher rates of early MRIs, explaining 84% of between-state variation, and 12.5% of all observed variability. Inter-state differences in MRI rates were greatest for lower-severity cases. Higher severity diagnoses were more common in high utilization states. Conclusions. Between-state inappropriate early MRI variability is largely explained by rate of non-hospital MRI sites and state median income. Potential solutions include efforts to address inappropriate referral patterns based on private MRI facility ownership, and to improve quality of communication with low-income patients.