Chronic Disease Medication Use in Managed Care and Indemnity Insurance Plans

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Abstract
To evaluate the impact of managed care on the use of chronic disease medications. Claims data from 1997 from two indemnity and three independent practice association (IPA) model managed care insurance plans. Cross-sectional analysis of claims data. Adult patients with diabetes mellitus (DM, n = 26,444), congestive heart failure (CHF, n = 7,978), and asthma (n = 9,850) were identified by ICD-9 codes. Chronic disease medication use was defined through pharmacy claims for patients receiving one or more prescriptions for drugs used in treating these conditions. Using multiple logistic regression we adjusted for patient case mix and the number of primary care visits. With few exceptions, managed care patients were more likely to use chronic disease medications than indemnity patients. In DM, managed care patients were more likely to use sulfonylureas (43 percent versus 39 percent for indemnity), metformin (26 percent versus 18 percent), and troglitazone (8.8 percent versus 6.4 percent), but not insulin. For CHF patients, managed care patients were more likely to use loop diuretics (45 percent versus 41 percent), ACE inhibitors or angiotensin receptor blockers (50 percent versus 41 percent), and beta-blockers (23 percent versus 16 percent), but we found no differences in digoxin use. In asthma, managed care patients were more likely to use inhaled corticosteroids (34 percent versus 30 percent), systemic corticosteroids (18 percent versus 16 percent), short-acting beta-agonists (42 percent versus 33 percent), long-acting beta-agonists (9.9 percent versus 8.6 percent), and leukotriene modifiers (5.4 percent versus 4.1 percent), but not cromolyn or methylxanthines. Statistically significant differences remained after multivariate analysis that controlled for age, gender, and severity. Chronic disease patients in these managed care plans are more likely to receive both inexpensive and expensive medications. Exceptions included older medications partly supplanted by newer therapies. Differences may be explained by the fact that patients in indemnity plans face higher out-of-pocket costs and managed care plans promote more aggressive medication use. The relatively low likelihood of condition-specific medications in both plan types is a matter of concern, however.