During a stay in hospital a patient's medicines may be changed. Studies suggest that almost half of all patients may experience an error with their medicines after they have been discharged from hospital. Community pharmacists can now use both medicines use reviews (MURs) and the new medicine service (NMS), as well as information from hospital colleagues, to improve patient care.

The transfer of patients and their medicines from secondary to primary care can lead to:

• The incorrect transmission of information
• Unintended changes in medication
• Intended changes in medication not being followed through (e.g. changes in medicine, dose or formulation)
• Continuation of medication that should have been stopped.

Figure 1 outlines the steps that need to be in place to ensure that medicines are obtained and used by patients as intended after discharge from hospital.

The standard contract for NHS hospitals has, since April 2010, required them to share discharge summaries with a patient's GP within 24 hours of leaving hospital. The information provided should include a summary of diagnosis and details of any medication prescribed at the time of the patient's discharge. The contract (and the NHS Constitution) also requires hospitals to give patients a copy of their discharge letter.

However the Care Quality Commission (CQC) found that this happened in only seven of the 12 areas it studied. All hospitals are expected to have a policy on discharge medicines and, increasingly, the aim of this is to reduce preventable problems (including unplanned readmissions) due to medicines issues after discharge.

The hospital's pre-discharge assessment attempts to take into account:

• The patient's previous care needs
• Changing medication needs (including compliance aids)
• Likely changes as a result of admission
• Transport and social needs (e.g. patient living alone)
• Possible vulnerabilities (e.g. frail elderly, terminally ill, learning disability, mental health problems)
• Eligibility for NHS continuing care (sometimes referred to as continuing healthcare).

Patients may be discharged to their own home or transferred to a community hospital or care home. Hospitals sometimes categorise discharges as 'simple' or 'complex', although there is no standardisation in this terminology. A 'simple' discharge can be defined as one that:

• Will involve minimal disturbance to the patient's activities of daily living
• Does not prevent or hamper a return to their usual place of residence
• Will not require a significant change in support offered to the patient and his/her carer in the community.

A 'complex' discharge is where one or more of these criteria do not apply. Patients may sometimes have a 'rapid discharge' with specific staff (part of a rapid discharge team) designated to facilitate this in order to release a hospital bed. Patients may be discharged home or to a less intensive care setting, such as intermediate or transitional care.

In addition, complex patients may be identified as having issues around polypharmacy. Whereas this previously referred to the number of medicines prescribed, it has recently been classified as 'appropriate' (where best evidence has been used to prescribe and medicines use has been optimised) or 'problematic' (where theintended benefit of medicines does not occur or multiple medications are used inappropriately). [See: The King's Fund: Polypharmacy and medicines optimisation]