Impact of emergency hospital admissions upon patterns of primary care prescribing: a retrospective cohort analysis of electronic records

Background Little is known about the impact of hospitalisation on prescribing in UK clinical practice. Aim To investigate whether an emergency hospital admission drives increases in polypharmacy and potentially inappropriate prescribing (PIP) in primary care. Design Retrospective cohort analysis Setting Primary care and emergency hospital admissions in England Methods Changes in number of prescriptions and PIP following an emergency hospital admission in 2014 (at admission and 4-weeks post-discharge), and 6-months post-discharge were calculated among 37,761 adult patients. Regression models were used to investigate changes in prescribing following an admission. Results Emergency attendees surviving 6-months (n=32,657) had, on average, 4.4 (SD=4.6) prescriptions prior to admission, and 4.7 (SD=4.7) (p-value<0.001) 4-weeks after discharge. Small increases (<0.5) in the number of prescriptions at 4-weeks were observed across most hospital specialities, except for surgery (-0.02, SD=0.65) and cardiology (2.1, SD=2.6). Number of PIPs increased after hospitalisation; 4% of patients had ≥1 PIP immediately prior to hospitalisation, increasing to 8% 4-weeks post-discharge. Across hospital specialities, increases in the proportion of patients with a PIP ranged from 2.1% for obstetrics/gynaecology to 8% for cardiology. Patients were, on average, prescribed fewer medicines 6-months, compared to 4-week post-discharge; 4.1 (SD=4.6) (p-value<0.001). Decreases in the number of prescriptions across specialities ranged from 0.2 (SD=1.6) for obstetrics/gynaecology to 0.9 (SD=3.5) for both cardiology and other medicines. PIPs decreased to 5.4% of patients. Conclusions Perceptions that hospitalisation are a consistent factor driving rises in polypharmacy are unfounded. However, hospitalisation may lead to increases in potentially inappropriate prescribing.