The Impact of Formulary Reservations on Drug Utilization: A Controlled Trial

ABSTRACT A controlled trial was conducted in two teaching hospitals (A and B), with similar case mixes to determine the impact of reservations, which were educational in nature, on the utilization of oral ciprofloxacin. Over a two-month period the health records of all the patients who received the drug were reviewed, and information on utilization and demographics of patients receiving the drug was recorded. As well, the number of admissions to the two hospitals over this period were compared. If culture and sensitivity (C & S) results were available, appropriateness was assessed in accordance with criteria for use established at site A; in the absence of C & S information, consensus by two microbiologists was used. Over the two-month period a total of 136 patients received ciprofloxacin at the two institutions. At site A, which had reservations, the number of patients who continued to receive ciprofloxacin upon admission was significantly decreased relative to site B, which did not have reservations (14% vs. 36% respectively, p = .029). As well, when assessed by total number of admissions to the institutions, the number of patients receiving ciprofloxacin at site A was less than site B (1.5% vs. 2.6% respectively, p = .003). While the utilization was decreased at site A vs. site B, the proportion of patients with therapy deemed to be appropriate was not different between the two sites. Educationally based reservations are an effective formulary tool for optimizing drug utilization. RESUME Une etude comparative a ete effectuee dans deux centres hospitaliers universitaires ou l'eventail des cas est similaire afin de determiner les repercussions de certaines restrictions d'origine didactique sur l'usage de la ciprofloxacine administree par voie orale. Pendant deux mois, on a passe en revue les dossiers medicaux des patients auxquels etait prescrit le medicament, pour recueillir les renseignements concernant l'utilisation de ce dernier et les donnees demographiques sur les patients. On a, en outre, releve le nombre d'hospitalisations dans chaque etablissement durant cette periode. Les cas pour lesquels des resultats de culture et d'epreuve de sensibilite (C&S) figuraient au dossier ont ete evalues d'apres les criteres d'utilisation du medicament etablis par l’etablissement A. Pour les autres cas, on s'est appuye sur l’opinion concordante de deux microbiologistes. Pendant les deux mois, l36 patients au total ont recu le medicament. La proportion de patients traites a 1a ciprofloxacine apres l'hospitalisation est nettement plus faible pour l'etablissement A, ou l'usage du medicament est sujet a des restrictions, que pour l'etablissement B ou n'existe aucune restriction (14% et 36% respectivement, p = 0,029). En outre, comparativement au nombre d'hospitalisations, la proportion de patients trates a la ciprofloxacine est plus faible pour l'etablissement A que pour l'etablissement B (1,5% et 2 ,6%respectivement, p = 0,003). Bien que le medicament soit moins souvent prescrit au site A, la proportion de traitements juges appropries est la meme dans les deux hopitaux. Les restrictions d'origine didactique constituent donc un moyen efficace d'optimiser l’utilisation des medicaments figurant sur les formulaires.