In a climate of evidence based medicine the Mirena intrauterine system is utilised as a treatment for menorrhagia based only on small studies comparing the Mirena system to endometrial ablation1–3. These studies do not have sufficient numbers to demonstrate a clinically meaningful difference and therefore there is a need to perform a large randomised controlled trial to assess the efficacy and tolerance of the Mirena intrauterine system against the established and effective endometrial technique for controlling menorrhagia. The current evidence is insufficient to make robust conclusions about satisfaction rates, discontinuation rates, quality of life outcomes or the health economics of the Mirena system. Further to previous correspondence4 the SMART study (Satisfaction with Mirena and Ablation: a Randomised Trial) was initiated as a multicentre randomised controlled trial based in Leeds. The trial was very well received by gynaecologists throughout the UK. Without exception all centres were enthusiastic and felt that recruitment would not be a problem. Twenty centres were at various stages in the trial process of site selection, ethical approval, initiation and recruitment. The aim was to recruit 300 women in an eighteen month period with approximately 15–20 patients required per centre. Despite extensive efforts by the trial team, however, nine months into the study only 24 women had been registered with 16 women randomised, the majority (16) registered at the principal trial centre at St. James's University Hospital. Clinicians from all centres involved have reported patient preference for treatment (usually endometrial ablation) as the most common barrier to recruitment. One participating clinician approached over 30 eligible women but only one agreed to be randomised!

Patient preferences are known to play an important role in treatment selection for menorrhagia5, so some reluctance to randomisation was anticipated and allowed for. It is the almost universal refusal to accept Mirena in the trial, however that was most surprising and reluctantly the study has now closed. We are disappointed that such a well designed, well received trial was unable to succeed despite very enthusiastic clinicians.

A qualitative study is now being planned to investigate the reasons behind patients'preferences. The Mirena intrauterine system is potentially a therapy with numerous benefits (no need for general anaesthesia, outpatient procedure and low complication rate), but with insufficient evidence to enable clinicians and their patients to assess with any degree of confidence the potential outcomes of treatment with Mirena. Should we therefore withhold such therapies until sufficient evidence is obtained or should we disregard evidence based medicine and prescribe such therapies without proof?


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