Evaluation of prescription charges in a health maintenance organization

Differing patterns in drug use and charge variances among three pharmacy sites were determined for a university-based health maintenance organization (HMO). Computerized prescription claim data for the HMO inhouse pharmacy and those chain and independent pharmacies contracting with the HMO were analyzed on a personal computer using database management and statistical software. Chain and independent pharmacies were under contract to charge the average wholesale price plus a $2.00 fee per prescription. Drug-claim data were separated by pharmacy site (inhouse, chain, and independent), and the data for each site were sorted by national drug code number. High-charge and high-use drugs were identified for evaluation on a unit-charge basis. During the six-month study period, 22,393 prescriptions were filled, representing total charges of $347,063.79. The mean per-prescription charges submitted to the HMO by the chain, independent, and inhouse sites were $14.99, $16.08, and $16.41, respectively. The inhouse pharmacy had many charges in high dollar ranges. Of 10 high-charge drugs analyzed, isotretinoin 40 mg, flunisolide nasal solution, naproxen 250 mg, cyclosporine oral solution, and atenolol 50 mg were dispensed in significantly different proportions at each site. There were significant differences in unit prices of nine high-use drugs among pharmacy sites. This study indicates the importance of evaluating adverse selection among pharmacy sites and the value of auditing claims submitted.