The Cost and Incidence of Prescribing Errors Among Privately Insured HIV Patients

Background: With the rapid growth in the volume of HIV-related studies that address drug interactions, appropriate medication regimens, and when and how to alter drug regimens, it is challenging for physicians to stay informed. Physicians require knowledge about all drugs taken by HIV patients in order to assess accurately the benefits and risks of various drug combinations.

Objective: To examine the cost and frequency of antiretroviral prescribing errors among a sample of privately insured patients with HIV disease.

Methods: Data were obtained from the MarketScan Commercial Claims and Encounter Database created by the Medstat Group Inc. The MarketScan database contains claims data for inpatient care, outpatient care, physician services and prescription drugs in benefit plans sponsored by >50 large employers in the US. This study compared data from the 1999-2000 MarketScan database with those from the 2005 MarketScan database. The 2005 MarketScan database includes 12,226 HIV enrollees who received antiretroviral drugs. This study compared the claims experience of HIV patients who filled a prescription for a drug combination that is not recommended by the US Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents with the claims experience of patients who did not receive such a prescription.

Results: In the 1999-2000 database the most common inappropriate drug combination involved the co-administration of a protease inhibitor (PI) and the lipid-lowering drug simvastatin, and 1% of patients experienced this type of error. In the 2005 database, only 0.4% of patients (46 of 12,226) experienced an inappropriate combination of simvastatin and a PI while 5.3% of patients (644 of 12,226) received atazanavir and tenofovir without ritonavir (referred to herein as 'boosting errors'). Patients who experienced a boosting error incurred higher annual costs than patients who took ritonavir along with tenofovir and atazanavir ($US 20,927 vs $US 16,704). Because atazanavir was approved by the US FDA in June 2003, medication errors involving atazanavir were not relevant in 1999 and 2000. Overall, it was found that HIV patients were three times as likely to experience an inappropriate drug combination in 2005 than they were in either 1999 or 2000 (5.9% vs 1.9%), and that this increase is attributable to boosting errors. In addition, the prevalence rate of HIV in the 2005 MarketScan database was almost triple that in the 1999 MarketScan database (0.14% vs 0.05%).

Conclusion: This study indicates that those who provide care to HIV patients must be vigilant in their efforts to provide patients with a drug therapy regimen that minimizes the chance of an adverse reaction and maximizes the potential to control viral replication.