The chances of a patient with a serious mental illness ending up in hospital because of their condition are reduced by almost 40 per cent if they have a care plan, according to the research.
The study, which tracked 20,000 patients with a severe mental illness through the healthcare system, also found that seeing the same GP reduced the risk of an unplanned hospital admission by around 25 per cent.
The findings demonstrate the importance of continuity of care at the GP's for improving health outcomes for patients with a severe mental illness, the authors of the study say.
Severe mental illnesses affect between one and two percent of the population and include conditions like bipolar disorder and schizophrenia.
People with a severe mental illness often experience a range of other physical health problems. Their life expectancy is around 20 years shorter than the general population and they also visit A&E more often and have higher rates of unplanned hospital admissions.
Lead author of the study, Professor Rowena Jacobs from the Centre for Health Economics at the University of York, said: "Finding ways to improve health care and outcomes for patients with severe mental illness is a high priority. Seeing a GP is often the only regular point of contact with health services for this group and so it's really important that they receive high-quality care at this stage of the system.
"Our study shows that continuity of care has the knock-on effect of reducing costly unplanned hospital admissions, which both saves the NHS money and could improve the stark health inequalities experienced by people with severe mental health conditions.
"Continuity of care through a care plan or seeing the same doctor means that doctors are able to pick up on problems quickly and understand a patient's needs better. Having to repeatedly explain co-morbid conditions and background information to a new GP at each doctor's appointment can be incredibly daunting and stressful for these patients."
The researchers explored two aspects of continuity of care - consistently seeing the same GP and care plans - which are documents which state what type of support is needed to meet a patient's needs. They detail a patient's history, circumstances, level of independence and include a personalised action plan for them.
The researchers found that seeing the same doctor reduced the risk of having to go to A&E by 8-11 per cent and the risk of an unplanned hospital admission by 23-27 per cent. Having a care plan reduced the risk of a visit to A&E by 29 per cent and an unplanned hospital admission by 32 per cent. It also reduced the risk of a patient being admitted to hospital for reasons linked to their mental health condition by 39 per cent.
The study is the first to link data sets in order to look at the entire health care pathway for patients in England. The research team controlled for other factors that could affect the health of patients (such as the severity of their mental health problems and any other medical conditions) in order to accurately assess the relationship between continuity of primary care and patient outcomes.
Professor Jacobs added: "while some hospital admissions are of course unavoidable and sometimes the best thing for a patient is to go into hospital, it is important to ensure that we do our best to spot and deal with avoidable crises at a primary care level.
"GPs are currently offered incentives to ensure patients with severe mental illness have a care plan and our study provides evidence that this should continue. A broader discussion also needs to be had about the importance to patient outcomes of seeing the same doctor and we need to look at new models of community-based care to ensure support that is much more integrated.
"Policy makers should take note of the strong effect we observed in terms of reducing hospital use - investing in continuity in primary health care will save a lot of money in terms of the big picture for the NHS."
Impact of family practice continuity of care on unplanned hospital use for people with serious mental illness is published in Health Services Research. The study was funded by the NIHR.