In this study, we analyzed existing hospital databases and compared the usage and acquisition cost of acid-suppressant agents for six-month time periods before (from January 1 to June 30, 2004) and after (from January 1 to June 30, 2005) the formulary switch of PPI products. The institutional review board (IRB) approved the protocol via expedited review prior to data collection. Patient consent and approval of the Health Insurance Portability and Accountability Act (HIPAA) were not required.
The University of Colorado Health Science Center is an academic institution with a 373-bed complement, including 48 ICU beds (medical or coronary, 16 beds; surgical, 16 beds; neurosurgical, eight beds; and burn or trauma, eight beds). The institution does not provide pediatric services. All ICUs have clinical pharmacy services with multidisciplinary patient-care rounds.
In September 2004, the P&T committee approved changes to the formulary, switching from several brands of PPIs to less expensive PPI formulations represented by only one brand. The PPI formulary had been stable for two years before this switch and had consisted of the following:
After the formulary switch, the 15- and 30-mg lansoprazole capsule was the only PPI available for patients tolerating oral intake; the 15- and 30-mg lansoprazole disintegrating tablet replaced the lansoprazole bulk suspension; and IV lanso-prazole 30 mg replaced IV pantoprazole.
A guideline directing the appropriate use of IV PPIs was implemented in January 2003 and was continued after the formulary change. The adherence rate to the guideline, assessed before the switch, was 64.9%, with nearly all IV doses administered in the ICU or immediately before transfer of the patient to an ICU.
In addition, an algorithm for SRMD promoted H2RA products, and PPIs were reserved for patients unable to tolerate H2RA formulations. The H2RA products on the formulary did not change; these consisted (Zantac canadian, Glaxo-SmithKline), generic ranitidine solution 150 mg/ml, and IV (Pepcid canadian, Merck). The daily frequency of administration for PPIs and H2RAs recommended by the P&T committee, according to the indication of use, was identical for each route of administration before and after the change.
Because of contractual agreements, we cannot share the actual costs of the products; however, nominal pricing for all lansoprazole products was obtained after the formulary switch. IV lansoprazole represented the largest difference in acquisition cost, because it was acquired at approximately a third of the cost of IV pantoprazole.
The cost of IV famotidine was minimally reduced after the formulary switch. The costs of all other PPI and H2RA formulations were comparable before and after the change. To maintain consistency, we used the cost of each product at the beginning of each time period; costs might have varied slightly over the duration of each time period.
To assess usage, we searched the pharmacy database for all doses of PPI and H2RA products charged for the six-month periods before and after the formulary switch. We exported these data directly into a Microsoft Excel spreadsheet. We chose the before-and-after time periods of January 1-June 30, 2004 and 2005, respectively, to prevent any potential awareness of an impending formulary switch from altering usage before the change and to provide time for adjustment to the new products after the switch.
Prescribers were notified via newsletters and e-mail of formulary changes, and cost data were provided. The only patient-specific data collected were hospital locations at the end of therapy and the specific route of drug administration. All doses for that regimen were assumed to have been given at the location of therapy completion.
Administration was then categorized for each dosage regimen as “ICU” or “emergency room” versus any other hospital location (non-ICU). The hospital billing database was used to standardize to patient-days, and usage was then categorized as ICU or non-ICU. The hospital billing system applied a case-mix index value to every patient according to billing codes. The index designates the level of care required. We compared the mean case-mix indices for each time period to ensure that patient groups possessed similar acuity levels.
Costs were applied to the cumulative doses of each product formulation and categorized as ICU or non-ICU. Hospital acquisition costs, in U.S. dollars, were used for all products except simplified lansoprazole suspension and lansoprazole disintegrating tablets, including a pharmacist’s time to compound the suspension or a nurse’s time to dissolve the tablets. We assessed these costs before the formulary change so that the P&T committee could ascertain the financial implications. We assumed that the time to prepare and administer a dose of any other product would be equivalent among the formulations used before and after the switch.
The primary outcomes of this assessment were the usage and associated drug costs of PPIs and H2RAs in non-ICU sites and in the ICU. Data were reported as cumulative totals or aggregate means for each six-month time period. We assessed changes in the route of administration, in ICU and non-ICU usage, and costs in relation to patient-days, and we used odds ratios obtained from 2 x 2 contingency tables. All tests were two-tailed, and odds ratios and 95% confidence intervals (CIs) were reported.