The number of complaints about hospital services on Wearside to the national watchdog jumped sharply in the last year.
However, new figures from the Parliamentary and Health Service Ombudsman show the majority of reports were rejected.
We place the very highest value on complaints as a method of developing our service and learning from patients about those aspects of our service where we need to improve.City Hospitals spokesman
The ombudsman received 65 complaints about Sunderland City Hospitals Trust in 2014-15, up from 50 in the previous 12 months.
Just 14 of those complaints were actually accepted for investigation, of which only two were upheld.
Eight were rejected and the remainder were still under investigation at the end of the period in question.
A City Hospitals spokesman, said: “We place the very highest value on complaints as a method of developing our service and learning from patients about those aspects of our service where we need to improve.
“We see every complaint as an opportunity, and although we believe our patients receive standards of care of the highest quality, comparable with anywhere in the NHS, we do accept that in a service treating thousands of patients there will be occasions when we fall short.
“Communication and accuracy of information are fundamental in the system, especially when the complexities of healthcare, and the sensitivities involved, are so marked.
Nationwide, the top three reasons for hospital complaints investigated by the ombudsman were poor communication, errors in diagnosis and poor treatment.
Parliamentary and Health Service Ombudsman Julie Mellor, said: “We know that there are many factors that influence the number of complaints hospitals receive, such as organisational size, demographics and whether they actively encourage feedback from patients.
“I strongly believe that NHS leaders should welcome feedback from patients and recognise the opportunities that good complaint handling offers to improve the services they provide.
“We are publishing this data to help hospital trusts identify problems and take action to ensure trust in the healthcare system remains high.”
The report reveals that the number of inquiries the Parliamentary and Health Service Ombudsman has received and investigated about acute trusts, increased year-on-year.
In 2014-15, the service received 21,371 inquiries about the NHS, compared to 18,870 in 2013-14. Of those, 8,853 were about acute trusts, compared to 8,178 in 2013-14.
It completed 1,652 investigations into acute trusts in 2014-15, compared to 852 in 2013-14, a result of a change in the way the service handles complaints, meaning it completed 10 times more investigations as in 2012-13.