CLET Trail for PCOS

Clomiphene versus LETrozole for ovulation induction in PCOS

This clinical trial is currently running at Royal Derby Hospital. It compares clomiphene citrate versus letrozole for ovulation induction in infertile women with polycystic ovarian syndrome (PCOS).

Many women with (PCOS) present with subfertility due to lack of ovulation. Clomiphene citrate (CC) is a medicine that has traditionally been used for more than four decades as the standard treatment to induce ovulation in these women. Although CC is very successful in achieving ovulation (75%), the chance of pregnancy with this treatment is low (only 35%). In addition, the chances of miscarriage (about 30%) and multiple births (about 7%) are increased with CC. The lower pregnancy and higher miscarriage rates during CC treatment have been attributed to the negative effects of CC on the neck and on the lining of the womb.

Letrozole is another medicine that has recently been investigated as a promising alternative to CC to induce ovulation in patients with PCOS. It has been used for several years in women for other indications and its safety is well established. Theoretically, letrozole offers several advantages over CC. In contrast to CC, letrozole, which is as successful as CC in inducing ovulation, does not affect the neck or the lining of the womb. Consequently, letrozole treatment may increase the chances of pregnancy and reduce miscarriages. In addition, letrozole has been shown to reduce chances of multiple pregnancies, a risk well known to occur with CC treatment. However, all these advantages of letrozole remain to be proven.

The aim of this study is to prove or disprove the superiority of letrozole over CC in generating better pregnancy rates with fewer miscarriages and fewer multiple pregnancies.

For the full details of the trial please click on this link: CLET Patient information sheet.pdf

The trial is registered with www. - identifier number is NCT00478504:

Saad Amer

Saad Amer MSc., FRCOG, MD
Consultant Gynaecologist

Private sec: 01332 785693
NHS Sec: 01332 786773
Private appointment: 01332 540104