Patients moving between health services are facing unnecessary risks because correct information about the medicines they are taking often does not transfer with them, the Royal Pharmaceutical Society (RPS) has warned.

4,041 errors were found in 3,091 reviews of patients' medicines carried out in 30 hospital trusts across England in September 2010, according to new statistics published in the Pharmaceutical Journal. Up to half the errors in the study were rated Level 3 on a risk reporting scale, meaning they could have resulted in a moderate increase in treatment with significant or non-permanent harm to the patient.

Over 80% of the Level 3 errors involved medicines used to manage serious long-term conditions such as heart disease, diabetes, asthma and Parkinson's, says the RPS, which also notes that patients with these conditions are often the most vulnerable to medication errors such as missed or wrong doses. 

Moreover, 162 of the errors were associated with high-risk drugs such as insulin, warfarin, steroids and antiepileptic medicines, it adds.

Approximately 4%-5% of hospital admissions are due to problems which could have been prevented by the correct use of medicines, and this is estimated to cost the NHS in England £466 million a year, says the RPS. Studies also suggest that almost half of all patients may experience an error with their medicines after they have been discharged from hospital, it adds.

Different health professionals may stop, start or change a patient's medicines while they are under their care at home, in hospital, a care home or hospice, but there is no standard procedure or specific accountability for communicating medicines information when the patient is discharged or moves places. Nor is there any agreed set of information which must be transferred about medicines, says the Society.

"This means the picture of a patient's medicines is often incomplete, leading to unintentional errors and discrepancies between what has been prescribed and what the patient is actually taking. Vital medicines can end up being missed out, duplicated or taken late," says Heidi Wright, policy and practice lead at the RPS.

The Society has published new practice guidance for health professionals, service commissioners and providers to outline a framework for action. The guidance - entitled Keeping patients safe when they transfer between care providers: getting the medicines right and which is endorsed by the Academy of Medical Royal Colleges, the Royal College of General Practitioners (RCGP), the Royal College of Nursing (RCN) and the Royal College of Physicians (RCP) - also recommends a set of core information about medicines which should move with the patient when they transfer from one care provider to another.

"We need a more joined-up approach to ensure patients don't experience further ill-health or readmission to hospital because their medicines are not right. The current lack of consistent procedures has a real impact on both patients and NHS budgets," says Ms Wright.

"As the NHS restructures, with more local commissioning and tendering for services, there is a real need to act now," she adds. 

And empowering and involving patient is also critical. "Patients can help by keeping an up-to-date list of their medicines and taking them with them when they go into hospital, so health professionals are fully informed about what they are taking. Patients should also ask for any changes to their medicines to be explained to them,” says Ms Wright.