How has polypharmacy changed in general practice since 2003? - a repeated cross-sectional study of a nationally representative sentinel network.

Problem

Polypharmacy is defined as the prescription of multiple concurrent medications, typically >5 drugs although there is no standardised definition. The ageing population places an increasing load on health services, especially general practice. Prescribing evidence-based therapies individually for multiple co-morbid conditions quickly results in polypharmacy. This increases the complexity in GP consultations, healthcare costs and also contributes to heavy pill burden on the individual patient level. In this study, we aimed to describe the trends in polypharmacy from 2003 to 2017, additionally looking at trends by age and gender.

Approach

This repeated cross-sectional study used the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) sentinel network. The mean prescription and drug counts for patients who consulted with their GP at least once at any point in the year was extracted for the period 2003 to 2017. The overall mean prescription and drug count was calculated and results were standardised to the Office of National Statistics (ONS) 2011 standard population. The mean drug and prescription counts were also stratified by Age and Gender. The proportion of individuals on 0-5, 6-9, 10-14 and 15+ drugs was also calculated for every year in the study period.

Findings

The overall mean prescription count showed a sharp increase from 2003 to 2004 (8.1 to 11.7). The same was observed for the overall mean number of different medications (2.5 to 3.1). Both counts continued to increase steadily until 2014, subsequent to which the mean prescription count plateaued and the mean drug count steadily decreased. Subsequent to 2013, the number of individuals on >5 drugs also declined steadily for all age-bands. Females had higher mean drug counts compared to males and individuals in the oldest age-band (75+) had the highest mean drug counts throughout the study period.

Consequences

The increases in overall mean prescription and drug count from 2003 to 2004 was associated with the introduction of the Quality Outcomes Framework (QOF). The plateauing and decline in polypharmacy are associated with measures such as Medicines Optimisation, Public Health England’s Antimicrobial Resistance Strategy. We are conducting on-going analysis to look at how prescribing varies according to socio-economic status, as measured by the Index of Multiple Deprivation (IMD), as well as ethnicity. We are also analysing how prescribing varies according to drug class (as stratified by British National Formulary (BNF) chapters). Ultimately, further research will need to be completed to identify potential explanatory factors explaining trends seen.