Research published today by the Journal of the Royal Society of Medicine concludes that patients admitted to hospital from care homes are commonly dehydrated on admission and consequently appear to experience significantly greater risks of in-hospital mortality.

Old and infirm people are at increased risk of dehydration, especially if they require assistance with drinking and, left to themselves, may not drink enough to avoid dehydration. Dehydration leads to high sodium levels, which can have severe consequences and which are an independent predictor of in-hospital mortality.

Researchers from Barnet and Chase Farm Hospitals NHS Trust, the University of Oxford and the London School of Hygiene & Tropical Medicine reviewed over 20,000 patients aged 65 years and over admitted to a London hospital trust for the first time between January 2011 and December 2013. While 1% of patients admitted from their own home were found to have high sodium levels, the figure for patients admitted from care homes was 12%. After adjustment for a number of possible explanatory factors, including age and dementia, the risk of high sodium levels was still over five times higher for those admitted from care homes.

Lead researcher Dr Anthony Wolff, of the Royal Free London NHS Foundation Trust, which acquired Barnet and Chase Farm Hospitals in July 2014, said: "Our study shows that too many patients admitted to hospital from a substantial number of care homes are dehydrated, leading to unnecessary loss of life. High sodium levels in care home residents should raise questions about adequate support for drinking."

Professor Martin McKee of the London School of Hygiene & Tropical Medicine and co-author of the research paper, added: "This raises serious concerns about the quality of care provided in some care homes. When a care home has more than a few residents admitted to hospital with high sodium levels this may well be indicative of a systematic problem at the care home and the issue should be raised formally."

Co-author Professor David Stuckler, from the University of Oxford, said: "Clearly this level of dehydration is a problem. Further research is needed to understand why it is occurring. Are care home residents choosing to drink less than they should? Or, as has been speculated, are care home staff not offering enough water to reduce incontinence and the amount of assistance their residents require?"