Inappropriate prescribing can include the intensification of existing drugs and the failure to stop or reduce doses of certain drugs after discharge from hospital.
The findings suggest that better coordination of care is needed to reduce avoidable medication related harms among these patients.
Potentially inappropriate prescribing is common among older adults and is associated with adverse outcomes including emergency hospital attendances and admissions, adverse drug events, and poorer quality of life.
Yet research to date has focused on characteristics of patients and general practitioners as risk factors for poor prescribing quality. There has been less focus on how health system factors, such as hospital admission or care transitions, may contribute to the appropriateness of prescribing for these patients.
So researchers, led by Tom Fahey at the Royal College of Surgeons in Ireland, in collaboration with the Department of Statistics and Data Science, Complutense University of Madrid, set out to determine whether hospital admission is associated with potentially inappropriate prescribing among older primary care patients (aged 65 years or more) and whether such prescribing was more likely after hospital admission than before.
They analysed data from 44 general practices in Ireland from 2012 to 2015. A total of 38,229 patients living in the community were included in the analyses. Average age was 77 years, 43% were male, and 10-15% of patients had at least one hospital admission each year.
Rates of potentially inappropriate prescribing were assessed using 45 criteria from the Screening Tool for Older Persons' Prescription (STOPP). The overall level of potentially inappropriate prescribing ranged from 45.3% of patients in 2012 to 51% in 2015.
Irrespective of age, sex, number of prescription items, other conditions, and health cover, hospital admission was associated with a higher rate of potentially inappropriate prescribing.
And among participants who were admitted to hospital, the likelihood of potentially inappropriate prescribing after admission was consistently higher than before admission, even after controlling for patients' characteristics.
This is an observational study, so no firm conclusions can be drawn about cause and effect, and the researchers cannot rule out the possibility that other unmeasured factors may have affected the results. However, the study included data from a large number of patients, and the findings are consistent with previous research in the field.
As such, the researchers say that hospital admission is "an important driver of potentially inappropriate prescribing and the overuse and/or misuse of drugs."
And they call for better coordination of care, particularly for older patients with complex care needs, to help reduce risk of medication errors, adverse drug events, and readmissions.
"Identifying optimal management strategies for older people is vital to ensure that the risk of inappropriate drugs is minimised after transitions of care," they conclude.
In a linked editorial, Professor Anthony Avery at the University of Nottingham and Professor Jamie Coleman at the University of Birmingham, say opportunities to intervene are often missed.
They point to the importance of interventions known to improve outcomes at discharge, including better communication between secondary and primary care, involvement of pharmacists, and closer monitoring of patients. In addition, making the best use of electronic health records for identifying patients at risk and providing decision support, is key to tackling potentially inappropriate prescribing, they conclude.