Potentially inappropriate prescribing according to STOPP-2 criteria among patients discharged from Internal Medicine: prevalence, involved drugs and economic cost.

Aim: This study aims to determine the prevalence of potentially inappropriate prescribing (PIP) among patients discharged from Internal Medicine, the drugs and factors associated and economic cost of PIP.
Methods: This retrospective cross-sectional, single-center study included participants aged ≥65 years consecutively discharged from the Internal Medicine Unit in a tertiary hospital of Southern Spain. PIP was defined by the Screening Tool for Older Persons Prescriptions (STOPP-2) criteria version 2 (2015 update). The association of PIP with chronic conditions was analyzed using multilevel logistic regression model. Data on economic cost associated to PIP were determined according to the computerized prescribing database of Andalusia ("Receta XXI").
Results: Out of the 275 patients studied, a total of 249 PIPs were detected in 114 (41.5%) patients of whom 79 (28.7%) had one or two STOPP-2 criteria and 35 (12.7%) 3 or more criteria. The most involved drugs were benzodiazepines (45.5%); antithrombotics (14.5%), including anticoagulants or antiplatelets, and opioids (11.4%). The multivariate logistic regression analysis identified polypharmacy (OR=11.00; 95% CI 1.41-85.52) and extreme polypharmacy (OR=26.25; 95% CI 3.34-206.07) as independent risk factors for PIP. The mean cost of PIP was €18.75±4.24 per patient and month. Opioids accounted for the highest percentage expenditure of PIP (39.02%), followed by inhaled bronchodilator drugs (30.30%), antithrombotics (12.20%) and benzodiazepines (7.92%).
Conclusions: PIP is frequent among patients discharged from Internal Medicine. The number of prescribed drugs was independently associated to PIP and benzodiazepines were the most involved drugs. PIP was associated to a significant economic cost.
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