Potentially inappropriate prescribing and cost outcomes for older people: a cross-sectional study using the Northern Ireland Enhanced Prescribing Database

PURPOSE: We sought to estimate the prevalence of potentially inappropriate prescribing (PIP) in the Northern Ireland (NI) population aged ≥70 years, to investigate factors associated with PIP and to calculate total gross cost of PIP.

METHODS: A retrospective cross-sectional population study was carried out in those aged ≥70 years in 2009/2010 who were in primary care in NI. Data were extracted from the Enhanced Prescribing Database, which provides details of prescribed and dispensed medications for each individual registered with a general practitioner. Twenty-eight PIP indicators from the Screening Tool of Older Persons potentially inappropriate Prescriptions (STOPP) criteria were applied to these data. PIP prevalence according to individual STOPP criteria and the overall prevalence of PIP were estimated. The relationship between PIP and polypharmacy, age and gender was examined using logistic regression. Gross cost of PIP was ascertained.

RESULTS: The overall prevalence of PIP in the study population (n = 166,108) was 34 %. The most common examples of PIP identified were proton pump inhibitors at maximum therapeutic dose for >8 weeks (17,931 patients, 11 %), non-steroidal anti-inflammatory drugs >3 months (14,545 patients, 9 %) and long-term long-acting benzodiazepines (10,147 patients, 6 %). PIP was strongly associated with polypharmacy, with those receiving seven different medications being fivefold more likely to be exposed to PIP than those on zero to three medications (odds ratio 5.04, 95 % confidence interval 4.84-5.25) The gross cost of PIP was estimated to be 6,098,419

CONCLUSIONS: Consistent with other research, the prevalence of PIP was high among the study cohort, increased with polypharmacy and was associated with significant cost.