More than eight out of 10 care home beds are provided by profit-driven companies, including more than 50,000 by large operators owned by private equity firms, research reveals.

Private companies now own and run 84% of beds in care homes in England used by older people, as local councils have almost totally withdrawn from a key area of social care they used to dominate.

The disclosure of the private sector’s huge market share has raised concerns because some of the biggest operators have large debts, are alleged to use tax avoidance schemes and drive down staff pay. The Care Quality Commission (CQC) watchdog has said inadequate staffing levels at care homes can lead to elderly residents receiving poor-quality care.

For-profit companies own 381,524 (83.6%) of England’s 456,545 care home beds, research by the IPPR thinktank (in partnership with Future Care Capital) has found, based on analysis of data from the CQC and Companies House, an increase on the 82% in 2015.

“The state has abdicated its responsibility for providing care over recent decades. The private sector may have filled this gap but it consistently puts profits before people,” said Harry Quilter-Pinner, a senior research fellow at the IPPR and co-author of the report.

“The fact that private equity-backed firms have taken over a significant share of the UK’s care provision, fuelled by debt and driven by the prospect of rising property prices and ever-lower care costs, puts our vital social care system at ever-increasing risk,” said Grace Blakeley, co-author of the report and IPPR research fellow.

In contrast, 13% of beds are provided by the voluntary sector and 3% by local councils, which for decades were the main provider of residential care for vulnerable older people.

“It’s shocking that so much of our social care is provided by large private providers who put profits before people and where too often the quality of care provided just isn’t good enough,” said Barbara Keeley, the shadow cabinet minister for mental health and social care.

“Social care is in urgent need of reform and yet the Tory government has abandoned responsibility for the care needs of older people and working-age people and they have no credible plan to fix this crisis.”

Ninety-one percent of councils have increased their use of private-sector care home beds since 2015 as alternatives have shrunk, the research shows. The IPPR analysed trends in bed use by 147 of England’s 151 councils. Overall, 133 of the 147 authorities had done that; just 14 had reduced their reliance on privately provided places.