title: Impact of cotherapy with some proton pump inhibitors on medical claims among HMO patients already using other common drugs also cleared by cytochrome P450.
abstract: Adverse drug event (ADE) rates resulting from coadministration of proton pump inhibitors (PPIs) and other drugs with potential for interaction with PPIs (DPIs) are unknown. This retrospective study assesses the occurrence of such ADEs and their potential impact on medical care costs by reviewing integrated medical and pharmacy claims. Managed care patients receiving one or more DPIs were identified. Within this sample, those who were also prescribed omeprazole or lansoprazole (DPI + PPI) were included. A second cohort (DPI alone) was created, matching for age, gender, and DPI use. Rates of ADEs were followed for 6 months after entry. Among PPI users, 58% used one or more DPIs, whereas 7% of DPI subjects used a PPI. Among claims arising from ADEs occurring in more than 1% of patients, 14 occurred in the DPI + PPI group and 2 occurred in the DPI-alone cohort, respectively, a highly significant difference. Crude odds ratios for the risks of specific ADEs were significantly increased for cotherapy with a PPI and warfarin, clarithromycin, corticosteroids, carbamazepine, nifedipine, or diclofenac. After adjustment, the first three associations remained significant. Coprescription of a PPI with potentially interacting drugs was common in practice and associated with significantly increased claims for medical care.
authors.affiliation: VA Medical Center and University of New Mexico, Albuquerque, New Mexico, USA.
authors.forename: Denis M
authors.initials: DM
authors.lastname: McCarthy
authors.forename: Trent P
authors.initials: TP
authors.lastname: McLaughlin
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Griffis
authors.forename: Cyrus
authors.initials: C
authors.lastname: Yazdani
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000305:Adrenal Cortex Hormones / Q000009:adverse effects; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000368:Aged; D002220:Carbamazepine / Q000009:adverse effects; D017291:Clarithromycin / Q000009:adverse effects; D015331:Cohort Studies; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004008:Diclofenac / Q000009:adverse effects; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000009:adverse effects* / Q000191:economics; D005260:Female; D006279:Health Maintenance Organizations; D006801:Humans; D064747:Lansoprazole; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000009:adverse effects; D016017:Odds Ratio; D009853:Omeprazole / Q000008:administration & dosage / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000191:economics; D054328:Proton Pump Inhibitors; D012189:Retrospective Studies; D012307:Risk Factors; D014859:Warfarin / Q000009:adverse effects
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000305:Adrenal Cortex Hormones; D004791:Enzyme Inhibitors; D054328:Proton Pump Inhibitors; D064747:Lansoprazole; D004008:Diclofenac; D002220:Carbamazepine; D014859:Warfarin; D003577:Cytochrome P-450 Enzyme System; D017291:Clarithromycin; D009543:Nifedipine; D009853:Omeprazole