One in four people do not know what an out-of-hours GP service is, figures show
The National Audit Office (NAO) said that "notable" proportions of the population do not know they can contact a GP service out of normal office hours or that they can call NHS 111.
A poll conducted by the NAO found that 26% of people have not heard of out-of-hours GP services, which provide urgent primary care when GP surgeries are typically closed.
And 19% had not heard of NHS 111 - the telephone service to provide speedy medical help when a problem is urgent but not a 999 emergency.
The poll of almost 900 people found that these people were more likely to go to A&E or call 999 if they or a loved one become unwell during the night or at the weekend.
Those who had not heard of out-of-hours GP services were almost five times as likely to call 999 at night than those who had heard of out-of-hours GP services, the NAO found.
"To use a particular option, people need to be aware of it, know how to contact it, and judge it appropriate for their situation," the NAO said.
"Awareness among certain groups, including younger people and people from black and minority ethnic communities, was lower than among others.
"People who had not heard of out-of-hours GP services were more likely to go to A&E departments or call 999 if they or their family felt unwell during the night or at the weekend."
The NAO's latest report also shows that the number of cases dealt with by out-of-hours services has fallen drastically in recent years. The number of cases fell from 8.6 million in 2007/08 to 5.8 million in 2013/14 - partly due to the roll-out of NHS 111.
On the service's finances, the NAO concluded that although some parts of the NHS in England are achieving value for money for their spending on out-of-hours GP services, this is not the case across the board.
Amyas Morse, head of the NAO, said: "Although some clinical commissioning groups are achieving value for money, this is not the case for the commissioning of all out-of-hours GP services.
"NHS England has much to do to help secure improvements throughout the system and to increase its oversight of the out-of-hours GP services it commissions directly.
"It should also work to raise public awareness of how and when patients should contact out-of-hours GP services, and needs to be prepared to take the lead in integrating these services effectively with other parts of the urgent care system."
An NHS England spokeswoman said: "NHS England welcomes the report and will consider it carefully and respond fully in due course.
"We are confident that the new out-of-hours assurance process brought in earlier this year (March 2014) is robust and has addressed many of the issues outlined by the National Audit Office.
"We will however carry on developing processes to ensure patients continue to receive high quality care and access to a GP outside of surgery hours."