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


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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Hellinger
Fred J
FJ
Center for Delivery Organization and Markets Agency for Healthcare Research and Quality, Rockville, Maryland 20850, USA. fhelling@ahrq.gov
Encinosa
William E
WE
D017088:AIDS-Related Opportunistic Infections / Q000188:drug therapy / Q000453:epidemiology; D000328:Adult; D000368:Aged; D019380:Anti-HIV Agents / Q000191:economics; D044966:Anti-Retroviral Agents / Q000191:economics* / Q000627:therapeutic use; D023241:Antiretroviral Therapy, Highly Active / Q000191:economics; D004347:Drug Interactions; D011307:Drug Prescriptions / Q000191:economics / Q000706:statistics & numerical data*; D004359:Drug Therapy, Combination; D017723:Drug Utilization Review; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000191:economics / Q000453:epidemiology*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000009:adverse effects; D015994:Incidence; D007356:Insurance, Pharmaceutical Services / Q000706:statistics & numerical data*; D016015:Logistic Models; D008297:Male; D008508:Medication Errors / Q000191:economics / Q000517:prevention & control / Q000706:statistics & numerical data*; D008875:Middle Aged; D012189:Retrospective Studies; D018894:Reverse Transcriptase Inhibitors / Q000191:economics; D017751:Safety Management / Q000379:methods; D019821:Simvastatin / Q000009:adverse effects; D014481:United States / Q000453:epidemiology
D019380:Anti-HIV Agents; D044966:Anti-Retroviral Agents; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D018894:Reverse Transcriptase Inhibitors; D019821:Simvastatin