Latest waiting list figures from the National Treatment Purchase Fund show that they continued to climb this month, reaching 558,484 last week.
There were 556,411 people waiting for an outpatient appointment with a consultant at the end of May, but the list increased by a 2,073 a week later.
At the end of April, there were 551,965 people waiting, with 4,446 added to the list last month.
Patient advocate, Stephen McMahon, said the outpatient waiting list needed to be addressed immediately.
Mr McMahon, who is chairman and co-founder of the Irish Patients’ Association, said he was “gravely concerned” about the matter.
The number of patients waiting more than 12 months had almost trebled over the last three years. “This is a frightening trend and a serious patient safety issue,” said Mr McMahon.
“A patient’s right to timely access to care, the avoidance of unnecessary pain and suffering, and to be treated with dignity are being denied.”
Fianna Fáil’s health spokesman, Stephen Donnelly, said there had been an increase of 40,000 in the number of people waiting for an outpatient appointment since the end of last year.
Mr Donnelly recalled that Simon Harris, the health minister, said he hoped to stabilise outpatient waiting lists this year. “He didn’t say what this meant but I doubt that anyone could define it as an increase of almost 8% in five months.”
The real concern was for people waiting a long period, the long waiterswhere there was an even bigger percentage increase —18% over the past 18 months.
“Some 106,145 have been waiting since at least November 2017,” said Mr Donnelly.
According to the NTPF figures, 106,145 people are waiting for more than a year and a half for an outpatient appointment.
However, the number of patients waiting for inpatient or day case treatment fell slightly, from 70,295 to 68,765.
There was also a fall of 107 in the number of patients waiting for a gastrointestinal test over the last two months — from 22,220 to 22,113.
The NTPF points out that 1,363 of the 27,928 waiting 15 to 18 months for an outpatient appointment have an appointment date within the next six weeks.
Also, 4,610 of the 106,145 waiting over 18 months have an appointment date within the next six weeks.