Authors said the findings should help GPs identify patients that may benefit from end-of-life care.
Understanding a person's risk of dying is vital to clinical and palliative care, they said. Yet there is a 'paucity' of research into care home mortality.
Patients in care homes are also more likely to be exception reported from QOF chronic disease targets, they said.
Researchers from St George’s University of London compared data on 9,772 elderly residents of care homes cared for by 293 general practices and 354,306 community residents in 2009.
Over 26% of care home residents died within one year, compared with 3.3% of community residents.
An analysis showed age was a weaker predictor of mortality risk in care homes than in the community.
The strongest predictors in both settings were the number of drug classes prescribed and contacts with primary care, in person or by phone, in the past three months.
Lead author Dr Sunil Shah said: 'Care home residents are a vulnerable group. It is important to understand mortality in care homes in order to ensure that residents receive appropriate elective, preventive and palliative care.'
He added: 'Our findings should help GPs have timely discussions with patients and their relatives about preferences for end-of-life care.'