Ownership and utilization of MR imagers in the Commonwealth of Virginia

Geographic Variation in Early MRI for Acute Work-Related Low Back Pain and Associated Factors

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.

LEVEL OF EVIDENCE

4.

Determinants of computed tomography and magnetic resonance imaging utilization in Taiwan

OBJECTIVES

Magnetic resonance imaging (MRI) and computerized tomography (CT) scanners are high-tech equipment with the highest utilizations and expenditures in Taiwan. This study investigates the factors that affect MRI and CT utilization, such as whether supply-side factors have more impact than demand-side factors, and the effect of utilization control policies.

METHODS

This study used the nationwide CT and MRI claim data for the years 1998 to 2001 from the Bureau of National Health Insurance (BNHI) in Taiwan. Multiple regression analysis was the statistical method used to determine the relative factors that influence CT and MRI utilization.

RESULTS

CT: population ratio, hospital-based physician: population ratio, female ratio, pediatric (< or =14 years) : population ratio, and family income significantly influenced CT utilization. MRI : population ratio and hospital-based physician : population ratio, female ratio, and family income significantly influenced MRI utilization. However, the proportion of the aged (> or =65 years of age) did not significantly influence CT or MRI utilization after controlling for other factors. The rates of CT and MRI utilization for the outpatient and inpatient settings and the repeated uses of CT or MRI have decreased significantly after a utilization review was implemented by BNHI, which suggests that CT and MRI have been overused.

CONCLUSIONS

Increases in supply-side factors significantly increase CT/MRI utilization, and supply-side factors impact CT/MRI utilization more than demand-side factors. The results show that the utilization instant report policy effectively decreases repeated uses of CT/MRI.

Economics of MRI technology

MRI development in the United States is reviewed from 1983 to the present with the intent of projecting future utilization and reimbursement. Since 1992, a decreasing rate of new installations and an aging installed base have markedly lowered the ratio between fixed and variable costs, thereby improving the ability to project cost per study. Variable costs are now estimated to average $175 to $200 per examination, up sharply from earlier reports. Actual costs per study usually exceed $400, even for high volume sites. Major cost contributors are reviewed and methods for identifying impediments to efficient operation are suggested.