Study questions assumptionsabout HMO effect on imaging

Membership rates and equipment use examined

It is a given in the diagnostic imaging industry that rising managed-careparticipation is accompanied by lower rates of health-care utilizationand a decreasing need for big-ticket imaging equipment.

But the results of a recent study conducted by Technology MarketingGroup in Des Plaines, IL, challenge that assumption. TMG researchersfound no correlation between participation rates of HMOs in selectedcommunities and several key measures of health-care use and demandfor imaging services.

"As long as procedural volume is stable or increasing,you're going to have increasing demand for technology. This reportsuggests that there may not be a change in utilization as HMOmembership rises," said John Vanden Brink, TMG managing partner.

The study included 53 U.S. communities with populations ofover one million. Data covering hospital admissions, length ofstay and inventories of four types of imaging equipment were comparedwith managed-care penetration. The study used TMG's 1993-94 equipmentcensus data, coupled with statistics from the American HospitalAssociation in Chicago and the Interstudy Group in Minneapolis.

The analysis indicated that there is no valid statistical relationshipbetween high or low HMO participation in a community and the size(per million population) of that community's MRI, CT, nuclearmedicine or cardiac cath equipment inventory.

No pattern emerged for any of the modalities individually ortaken as a whole, Vanden Brink said. Nor could correlations befound between HMO participation rates and hospital admissions,average length of hospital stay, adjusted patient days and otherutilization measures.

"These data fly in the face of conventional wisdom,"he said.

Nothing that analysts Mark D. Johnson and Loretta Loncoskeof MDB Information Network in Dallas have learned from their dailycontact with hospital administrators disputes TMG's findings.

"For the particular procedures that were examined -- CT,MR, nuclear medicine and cardiac cath -- we're not going to seea dramatic change in procedures based on HMO enrollment,"Johnson said.

Johnson does not anticipate much growth in the purchase andinstallation of these types of devices, however.

In most communities, managed care has not been a major influencelong enough to measurably affect equipment installed bases, Loncoskesaid.

"The years 1993 and 1994 -- when measurements reportedin the TMG study were taken -- were the ground floor for managed-caregrowth. We will see some change from 1993 to 1994 and a more radicalrate of change between 1994 and 1996," she said.

The results provide good and bad news for equipment vendors,according to Vanden Brink. The demand for equipment may not declineas steeply as some vendors feared, because utilization rates aremore resilient than expected, he said. But hospital mergers andconsolidations -- a factor outside the survey's scope --may meanthat purchasers have more buying power and can use their existingequipment inventories more efficiently, he said.