Inappropriate drug combinations among privately insured patients with HIV disease

The objective of this study was to examine inappropriate drug combinations among privately insured patients with HIV disease.

Data were obtained from the MarketScan Commercial Claims and Encounter Database for the years 1999 and 2000.

Each of the 2110 person-years of data examined in this study represents the claims experience of an enrollee with HIV disease who filled an antiretroviral medication prescription in either 1999 or 2000 for a protease inhibitor or nonnucleoside reverse transcription inhibitor. This study compares the claims experience of patients with HIV who filled a prescription for an inappropriate drug combination as specified in guidelines jointly issued by the U.S. Department of Health and Human Services and the Henry J. Kaiser Family Foundation with the claims experience of patients who did not.

An inappropriate drug combination was found in approximately 2% of the person-years of data, and persons who experienced an inappropriate drug combination had higher claims costs. One half of all of the inappropriate drug combinations involved a single lipid-lowering agent (simvastatin). Protease inhibitors decrease the activity of the enzyme that metabolizes simvastatin, and high concentrations of simvastatin have been associated with muscle damage. We found that patients who received protease inhibitors and simvastatin were more likely to experience muscle damage.

Persons with HIV have compromised immune systems and often take many medications. Thus, the risk and consequences of medication errors are severe, and both providers and patients should carefully monitor drug regimens to ensure that they are both safe and efficacious.