GP Practice Variation in Potentially Inappropriate Prescribing in Middle-Aged Adults: A Repeated Cross-Sectional Study

Problem

Potentially inappropriate prescribing (PIP) in primary care has been linked to adverse outcomes for patients. Despite similar rates of PIP amongst middle-aged and older adults, there is little literature focussed on the former. PIP is not evenly distributed in the population; a number of studies have identified factors such as age, sex, polypharmacy and socioeconomic status that influence PIP in both older and middle-aged adults. However, there is little known about practice-level factors that may influence PIP, particularly in middle-aged adults.The objective of this study is to estimate between-practice variation in PIP and evaluate patient and GP practice characteristics that influence this.

Approach

A repeated cross-sectional study using the Lambeth DataNet. Participants are registered patients aged 45-64 years old who have been prescribed at least one medication from 2014-2019. The primary outcome is prevalence of PIP, identified using the PROMPT (PRescribing Optimally in Middle-aged People’s Treatment) criteria. Measures of variation in PIP between practices will be quantified (systematic coefficient of variation) and multilevel negative binomial regression models used to examine patient and practice level variables to explain variation in prescribing (e.g. Quality Outcome Frameworks (QOF) achievements, presence of practice-based pharmacists, training practice etc).

Findings

The study sample included 44,082 participants from 40 GP practices of 360 individual GPs in 2019. This included one dispensing practice and 18 teaching practices. The mean QOF score was 534 (lowest: 467, highest: 558, maximum achievable: 559). The most common ethnicity was White (51%), followed by Black/African/Caribbean/Black British (32%) and Asian/Asian British (8%). 52% of participants suffered from multimorbidity, 28% had polypharmacy and there was a mean Index of Multiple Deprivation (IMD) decile of 3.91. Prevalence of PIP was 18.18% in 2019, with the PIP criterion of the use of two or more drugs from the same pharmacological class being the most common. Analysis of variation and explanatory variables is now underway.

Consequences

This is the first study to evaluate practice level factors that influence prevalence of PIP in middle-aged adults. By doing so, causes of variation in PIP can be determined. This will aid further development of effective and targeted interventions for medicines optimisation, resulting in safer care for patients.