Royal College of Obstetricians and Gynaecologists

The levonorgestrel-releasing intrauterine system (LNG-IUS, Mirena^®), although effective at reducing heavy menstrual bleeding, is inferior to endometrial ablation (Novasure^®) for the treatment of heavy menstrual bleeding. Ms Pleun Beelen, a medical student at the University of Maastricht, The Netherlands, presented results from the randomised controlled MIRA trial, comparing the LNG-IUS versus endometrial ablation in women with heavy menstrual bleeding, at the Royal College of Obstetrics and Gynaecologists (RCOG) World Congress 2019.

"If you were my patient, presenting to me because you had heavy menstrual bleeding, I would tell you that with both treatments you have a large chance of symptom relief and of being satisfied. [However,] if you choose the LNG-IUS it is more likely that you will need another intervention to get the same result as if you start with endometrial ablation."

The LNG-IUS and endometrial ablation are both frequently recommended treatments for women with heavy menstrual bleeding; however, to date, there have not been reliable data comparing their effectiveness.

"The LNG-IUS has advantages over endometrial ablation. It is reversible, it is less invasive and it also has a contraceptive effective," said Ms Beelen. "If LNG-IUS is comparable in effectiveness to endometrial ablation, it would be the preferred treatment. Therefore, we decided that a non-inferiority trial was the best design for our study."

This randomised controlled trial, included women with ≥4 years heavy menstrual bleeding (Pictorial Blood Assessment Chart (PBAC) score exceeding 150 points) and no future child wish. Patients came from 26 different hospitals and GP practices in The Netherlands.

Women with intracavitary pathology and abnormal cervix cytology were excluded from the trial.

Women were randomised to a strategy starting either with a LNG-IUS (n=132) or with endometrial ablation (n=138).

The primary outcome was the PBAC score at 24 months of follow up. The non-inferiority margin for the study was 25 PBAC points.

Secondary outcomes were patient satisfaction, complications, number of reinterventions, menstrual bleeding pattern, quality of life, sexual function, sick leave and costs. The team also measured the level of coagulation factors.

The mean age in both groups was 45 years and the mean body mass index in both groups was 28. The PBAC score was similar in both groups: 616 in the LNG-IUS group and 630 in the endometrial ablation group.

"If you assume a menstrual period of around five days, this [a PBAC score >600] is comparable with the use of around 12 fully soaked tampons or six large fully soaked pads during each day of menstruation. As you can imagine, this interferes with a woman's quality of life,” explained Ms Beelen.

After 24 months, 115/132 women in the LNG-IUS arm and 132/138 women in the endometrial ablation arm remained in the trial.

There was a steep decrease in PBAC scores in both groups. At 24 months, there was a PBAC score of 65 in the LNG-IUS group and 14 in the endometrial ablation group, with a difference of 51 (95% confidence interval; P_{non-inferiority}=0.87). "Therefore, non-inferiority [of LNG-IUS to endometrial ablation] could not be demonstrated," explained Ms Beelen.

A total of 39% of women in the LNG-IUS group discontinued treatment versus none in the endometrial ablation group. A further 35% of women in the LNG-IUS group needed reintervention, versus 20% in the endometrial ablation group. Endometrial ablation was the most common reintervention in the LNG-IUS group and hysterectomy rates in both groups were comparable (7% vs 10% in the LNG-IUS group and endometrial ablation group, respectively).

Satisfaction in both groups was comparable (74% vs 84% in the LNG-IUS group and endometrial ablation group, respectively). There was no difference in quality of life and sexual functioning in either group.