Researchers at the medical center have found that chronic disease patients in managed-care plans such as HMOs were consistently more likely to receive medications recommended for their condition than were patients covered by traditional indemnity insurance. The finding, contrary to common perceptions of managed care, applied to both newer, more expensive medications and older, less expensive ones.

The most likely explanation is that managed-care enrollees have lower out-of-pocket medication costs thanks to prescription drug benefits, which most managed-care plans have but indemnity plans lack, said Randall Stafford, MD, PhD, assistant professor of medicine at the Stanford Center for Research in Disease Prevention. Stafford is lead author on the study, which appeared in the April issue of the journal Health Services Research.

The findings, based on analyses of data from five health plans in 1997, seem to dispel the notion that managed-care plans withhold needed care — at least when it comes to medications.

"The perception that managed-care plans withhold expensive services from their members is not supported by our research," Stafford said. "While there may be areas where this phenomenon operates, it appears not to have been the case with chronic disease medications."

Stafford and colleagues at Boston’s Beth-Israel Deaconess Hospital, Massachusetts General Hospital and the University of Massachusetts Medical School analyzed 1997 claims data from three managed-care plans and two indemnity insurance plans in the Northeast. The managed-care plans followed the "IPA model" in which participating physicians belong to groups known as independent practice associations that contract with managed-care plans on their behalf.

Using the health plans’ medical claims, researchers identified all patients in the plans with diabetes (26,444 patients), heart failure (7,978) or asthma (9,850). The researchers then determined how many of these patients had filled at least one prescription for one of 18 medications or medication classes used to manage these diseases, including metformin and glyburide for diabetes, ACE inhibitors for heart failure and inhaled corticosteroids for asthma. Finally, researchers compared the use of these medications by patients in the managed-care plans vs. the indemnity plans. To compensate for differences in the plans’ patient populations (the indemnity plans had more older, sicker patients, for example) the researchers used risk-adjustment tools to analyze their data.

Even after adjusting for age, acuity and other factors, researchers found that managed-care patients were significantly more likely to have received medications. For diabetes treatment, metformin (brand name Glucophage) was used by 26 percent of managed-care patients compared with 18 percent of indemnity patients. For heart failure, ACE inhibitors including lisinopril (Zestril) and losartan (Cozaar) were used by 49 percent of managed-care patients vs. 40 percent of indemnity patients. For asthma, short-acting beta-agonists including albuterol (Ventolin) were taken by 42 percent of managed-care patients compared with 33 percent of indemnity patients.

These differences were more pronounced for newer, more costly drugs, contradicting the notion that managed-care plans limit access where cost is a factor. The differences were smaller or reversed for a small set of older drugs.

"Almost across the board, we found that managed-care patients were more likely to receive these medications," Stafford said. The most likely explanation is that because the managed-care patients had lower out-of-pocket costs thanks to their prescription-drug benefits, they were more likely to get prescriptions filled. And with their low co-payments for doctor visits, the managed-care patients may have seen their doctors more often than the indemnity patients, providing more opportunities to obtain prescriptions. The study was unable to examine the extent to which patient or physician factors may have led to the differences.

The consistent use of chronic disease medications is generally positive, Stafford explained, as the medications play a key role in managing disease and preventing acute episodes. But in some cases, he noted, the use of new medications can carry unknown risks, as happened with the diabetes drug troglitazone (Rezulin) that was later taken off the market because of harmful side effects. "The drug benefit seems to make a difference in whether patients take their medications — and that makes a difference in their quality of care," Stafford said.

The study, which was funded by the Robert Wood Johnson Foundation, has important health-policy implications. Stafford said the findings argue in support of a Medicare drug benefit, since such a benefit would likely increase the use of chronic disease medications among beneficiaries who need them.

 

The charts to the left show that for most of a set of 18 medications or medication classes studied, patients with chronic disease who were enrolled in managed-care plans were significantly more likely than patients covered by indemnity insurance to have received the medications often recommended to treat their conditions. Chart: Amy Feldman