Assisted conception on the NHS.

EDITOR, -David T Baird wonders why governments have reservations about assisted conception techniques for managing infertility. ' Surely one of the reasons is the poor quality of evidence for the effectiveness of some treatments, which we review in the most recent issue of Effective Health Care.2 Many subfertility treatments have not been evaluated by randomised controlled trials. For example, there is no published report of a randomised controlled trial comparing in vitro fertilisation and embryo transfer with an untreated control group (for example, subjects in whom treatment is delayed). Similarly, the view that medical treatment of amenorrhoea is highly effective is based entirely on retrospective reviews. Estimating the increase in pregnancy rate over the often appreciable spontaneous pregnancy rate that would have occurred in the absence of treatment is often difficult.3 The relative effectiveness of in vitro fertilisation and embryo transfer and other assisted conception techniques is not clear for various reasons. For severe bilateral occlusion of the fallopian tubes in vitro fertilisation and embryo transfer is the only possible treatment, but for women with at least one patent and healthy fallopian tube there is controversy over which technique is best. Well designed randomised controlled trials are needed to answer questions about the best technique for particular indications and patient characteristics.4 Different treatments may have different effects on the monthly fecundity and cumulative pregnancy rates. For example, prednisolone treatment of antibodies to sperm may need longer follow up before improvement in male fertility is observed. With assisted conception the effects are more rapid. Therefore, to compare treatments time must be incorporated into the analysis. Many studies, however, do not report the duration of follow up or number of cycles of treatment. Often life table analysis cannot be used appropriately because of the lack of information about nonrandom drop out of patients. Small studies cannot reliably answer questions of efficacy and may result in potentially effective interventions being dismissed prematurely. To increase the size of their study some authors group together patients with various causes of infertility, but this makes interpreting the results difficult. Another approach is to use meta-analysis to pool the results of small studies. Variability in the selection of patients, treatment, and measurement of outcomes is so great among studies, however, that aggregating results can be misleading. Lack of good quality evidence on the effectiveness of treatment for subfertility has contributed to health authorities' often sceptical stance.5 These treatments must be evaluated thoroughly before they become generally available on the NHS.