Potentially inappropriate prescribing in patients on admission and discharge from an older peoples' unit of an acute UK hospital.

BACKGROUND: The Screening Tool of Older Persons' potentially inappropriate Prescriptions (STOPP) classifies 65 common drug issues found to contribute to inappropriate prescribing in the elderly. International studies using STOPP criteria indicate high potentially inappropriate medication (PIM) prevalence rates; however, no studies have been conducted in older patients in UK hospitals. Published literature has not assessed whether prescribers attempt to minimise the potential risk of PIMs by putting in place follow-up or review plans.

OBJECTIVES: The objectives of this study were (1) to determine prevalence and types of PIMs in older people admitted to and discharged from a UK hospital; and (2) to determine how often PIMs prescribed on discharge are accompanied by a plan for follow-up.

METHODS: This was a retrospective, non-randomised study conducted in the Specialist Health and Ageing Unit (HAU) of a 950-bed acute hospital trust in England, UK. The subjects were patients aged ≥65 years admitted to the HAU in June and July 2011. Data were obtained by applying STOPP criteria to electronic admission and discharge medication lists. Parametric and non-parametric tests were performed to assess variables and to detect differences between groups. A PIM index was calculated by dividing the total number of PIMs by the total number of medications.

RESULTS: Medication lists for 195 patients were assessed. Median age was 85.5 years. The median number of admission medicines was nine. A total of 66 patients (34 %) were prescribed more than ten medications. The median number of discharge medicines was ten, with 80 patients (41 %) prescribed more than ten medicines. Admission PIM prevalence was 26.7 % (95 % CI 20.5-32.9; 52 patients, 74 PIMs). The most common PIM categories on admission were central nervous system (CNS) and psychotropic drugs, drugs adversely affecting patients at risk of falls and drugs acting on the urogenital system. The likelihood of having a PIM on admission was doubled in patients receiving more than ten medications compared with those taking fewer (odds ratio 2.3 [95 % CI 1.2-4.4]; p = 0.01). Discharge PIM prevalence was 22.6 % (95 % CI 16.7-28.5; 44 patients, 51 PIMs). PIMs reduced significantly on discharge (p = 0.005). The most common discharge PIMs were drugs adversely affecting patients at risk of falls, CNS and psychotropics, urogenital drugs and cardiovascular agents. Advice for general practitioners to monitor medication was documented on the discharge summary of three patients. An index was developed, based on the ratio of PIMs to medication totals. The PIM index complements the assessment of PIM prevalence and allows comparison of prescribing appropriateness between populations and between studies by taking into account the total amount of prescribed medication. Despite an increase in medication prescribed, the PIM index (rate) decreased from 0.043 on admission to 0.027 at discharge.

CONCLUSIONS: Admission to a specialist HAU was associated with a significant reduction in PIMS. Very few patients discharged with a PIM had a documented follow-up plan. PIM prevalence was lower than published rates found internationally. Similar studies in settings of varying types across the UK are needed.