HMOs with greatest market share adopt MR technology at slower rate

Jul 22, 2004

The bigger, the better -- or so the expression goes -- unless the topic is health maintenance organizations (HMOs) and their use of advanced MRI. In that case, the larger the HMO, the less likely it is to invest in bigger and better MR technologies.

Researchers from Stanford University School of Medicine in Stanford, CA, reached that conclusion after analyzing the relationship between HMO market share and the placement of MRI technology.

"Increases in managed-care activity in an area are significantly associated with reductions in the availability and use of MRI and with changes in the characteristics and capabilities of the equipment that is available...attention to the potential for managed care to inhibit adoption (and) to slow growth is warranted," wrote Laurence Baker, Ph.D., and Dr. Scott Atlas in the Journal of the American College of Radiology (July 2004, Vol. 1:7, pp. 478-487).

To that end, the duo reviewed HMO activity with regard to MRI in the mid-to-late 1990s. Their data consisted of MRI census information collected by research firm IMV Medical Information Division of Des Plaines, IL, in 1992, 1993, 1996, 1997, 1998, and 1999. More specifically, they looked at the following issues:

Overall availability of 1.5-tesla magnets.

Changes in MRI use.

Use of intravenous contrast agents.

Use of power injectors.

Use of specialized hardware and software.

Use of echo-planar imaging, cardiac MRI, and interventional MR.

The HMO markets were then classified into three groups, based on market share: low (<10% of the market share), medium (10%-25%), and high (>25%). Over a three-year period, they found that the groupings remained fixed, with 250 low markets, 52 medium markets, and 20 high markets.

According to the overall results, there was a significant increase in the number of MRI sites, scanners, and procedures between 1993 and 1999, both in and out of hospitals. In 1999, on average, 15% of all sites had power injectors, 33% owned echo-planar imaging equipment, 19% used cardiac MRI, and 16% offered interventional MRI.

The picture wasn't as rosy when broken down by market share. In 1993, the researchers found that high-share HMO markets had 0.43 fewer magnets per 100,000 people enrolled than low-share HMO markets. The situation had not improved six years later, with low-share HMO markets still leading by 0.71 more MR units than high-share HMO markets.

Looking more closely at hospitals, low-share HMO markets had 0.54 magnets per 100,000 people, while high-share HMO markets had 0.21. In 1999, low areas had 1.18 hospital magnets per 100,000 people, compared with 0.62 in high market-share areas.

In addition, high-share HMO areas tended to use contrast agents less often. In 1993, 37% of both hospital and non-hospital sites in low-share HMO markets performed contrast MR exams, compared with 30% of high-share HMO markets. Low-share HMO markets continued an upward trend in contrast use in 1997, to 39.8%, with a moderate drop-off in 1999 to 36.8%. In comparison, contrast MR growth was much slower in high-share HMO areas, creeping up to 32.3% in 1997 and 35.8% in 1999.

Finally, although the authors found less availability of advanced imaging technologies in high-share HMO markets, the difference was not statistically significant, they wrote. By 1999, for example, 18.5% of low-share HMO areas had power injectors, compared with 18% in high-share HMO markets. Also, 21.5% of low-share HMO sites were using cardiac MR versus 12.8% of high-share HMO areas.

The authors offered a theory as to why high-share HMO areas are lagging behind in MRI use: money. In order to rein in costs, HMO-run hospitals (versus outpatient settings) may have too tight a chokehold on MR use, thereby restricting the modality's growth and diffusion.

"At the same time, we cannot rule out that the availability and use patterns seen in hospitals in high-(share) HMO areas are the 'appropriate' levels and that faster growth seen in lower(-share) HMO areas...reflects overuse," they added.

The use patterns could be problematic on two levels, they suggested. First, overuse of MR on "marginal" patients could result in incidental findings or even the diagnosis of pseudodisease. However, patients could also be shortchanged in their diagnosis and treatment because of a lack of more advanced MR equipment.

Finally, there are basic issues of supply and demand. "If demand for new MRI equipment is slowed, the incentives to driving new developments and new products are also likely to be reduced, slowing the pace of advancement and deferring potential future benefits," Baker and Atlas wrote.

By Shalmali Pal
AuntMinnie.com staff writer
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