Objectives Older adults are a vulnerable and growing segment of the population with a high burden of comorbid conditions. As a consequence of increased co-morbidity, drug use in older adults is high, and polypharmacy has been linked to higher risk of adverse drug–drug interactions, morbidity, and mortality. The aim of the study was to evaluate the prevalence and nature of potentially inappropriate medications (PIMs) in a group of hospitalised older patients, and verify whether the use of ‘Beers criteria’ and/or ‘START & STOPP’ criteria could lead to deprescribing of drugs and reduce the length of stay in the hospital.

Methods Two hundred acutely ill patients aged ≥65 with multimorbidity admitted to the Division of Internal Medicine were enrolled in the study. Enrolled patients were admitted as medical emergencies and observed during their hospitalisation at the Emergency Department and subsequently at the Division of Internal Medicine. The pharmacological treatments taken by patients at home, during hospitalisation and at discharge, were examined, identifying inappropriate prescriptions (IPs), according to ‘Beers criteria’ and ‘START and STOPP’ criteria.

Results There were 487 IPs: 175 according to the Beers criteria; 50 according to the STOPP criteria; one according to the START criteria; 107 major interactions; 152 minor interactions; one off-label drug; and one duplicated pharmacotherapy. Twenty-three adverse drug reactions (ADRs) were recorded: the most frequent were abnormalities of serum electrolytes (35%); haemorrhagic events (22%); and accidental falls from benzodiazepine use (9%). The correct application of these criteria decreased IPs by 38% and reduced the number of drugs prescribed by the physician during the stay in the medical ward and at discharge by 19%.

Conclusions The use of criteria that detect IPs reduced PIMs and ADRs, increased safety in older patients, and reduced the number of drugs prescribed but did not reduce the length of stay in hospital.