A record number of people were sent to A&E in Yorkshire and the Humber by the NHS 111 helpline in December.
The increase in both A&E referrals and the number of patients admitted to hospital across England shows the strain the NHS is under, the healthcare research group the Nuffield Trust says.
NHS England data revealed that the Yorkshire and the Humber 111 line recommended 16,418 A&E visits times in December – the most in the last month of any year since 2013, the earliest period for which data is available.
Of the calls assessed at the centre, 11.3% ended with a referral to emergency departments – up from 9.3% in December the previous year.
NHS 111 is a 24-hour helpline for patients seeking non-urgent medical help, which replaced NHS Direct and some GP out-of-hours services in 2014.
Callers answer questions about their symptoms, asked by an adviser who can refer them to appropriate services for their condition.
Across England, more than 120,000 callers to the 111 helpline were referred to A&E in December – more than in any other month since records began in 2010.
Trips to emergency departments were the recommendation in 8.6% of calls, the highest proportion for any December since 2010.
Sarah Scobie, deputy director of research at the Nuffield Trust, said the findings underlined the pressure on the NHS.
She said: “Not only are there significant numbers of people turning up to A&E – more than 2.1 million people attended A&E in December - but more people than in previous years are also deemed ill enough to have to be admitted into hospital.
“By far the most common service NHS 111 sends people to is general practice, but we know that this is another bit of the system that is under immense pressure. It is going to take time and money and, crucially, staff for this pressure to ease in the long run.”
An ambulance was sent for 12.9% of the 146,000 calls assessed in Yorkshire and the Humber in December, while advisers referred 59.2% to primary care, such as GP surgeries, pharmacies and dentists. A further 3.3% were advised to rest at home.
An NHS spokesman said: “Like their colleagues in A&E, NHS 111 teams had their busiest month on record in December as the public’s trust in the service continues to grow, so it’s no surprise that more and more people with serious health needs are using it as their first port of call for advice.
“Three in 10 people who use the service would have gone to A&E for their urgent care needs had it not been available, so actually over the last 12 months it has spared 2.8 million unnecessary trips to hospital.”