Media pluckers strike again

Gulf in success rates of IVF clinics, was the predictable headline that greeted the publication this week by the Human Fertilisation and Embryology Authority's annual guide to clinics, both NHS and private. "Some produce babies in more than half of attempts and some are successful in only one in 10," indignantly frothed one report. So as 80,000 people besiege the authority's website thinking they are accessing an in vitro fertilisation shopper's guide, what is the science behind league tables like these?

Er, none as far as I can see. The authority has rightly long resisted producing league tables for success, saying that clinics cannot be directly compared. No, the tables produced in various papers were the result of random media data plucking (a little known branch of the science of journalism), and were not reproductions of actual HFEA league tables.

Although the data supplied by the 85 licensed clinics is broken down by age group (because increasing maternal age is strongly associated with a reduced chance of pregnancy) there is still a great deal of data that is not included. And, as we all know, the devil lies in the detail.

If one clinic has a highly selected population of patients - with, for instance, no previous history of failed treatments or concurrent medical conditions - its success rates cannot be compared with those of a clinic prepared to take on all who walk through the door. It's the old apples and pears argument.

The Cromwell Hospital in London, for instance, lurks in the bottom six yet has a strong reputation for taking on couples who had many failures in previous clinics. These are perforce going to be older, but also demonstrably infertile and therefore much less likely to get pregnant.

This might sound a bizarre thing to say about those attending an infertility clinic, but it is estimated that a third of couples seeking treatment are not infertile, just impatient. This is not a pejorative statement.

One of the greatest design faults in humans is their lack of an external fertility indicator. When you are 38, and the bloke has finally appeared on your horizon, the idea of waiting for two years to see if you can make babies is not an option, given that IVF success after 40 has begun a freefall descent. Even six months of fruitless bonking at this age is enough to send couples rushing headlong to infertility clinics, though conception might have happened by itself in time. Without a crystal ball, there are no other options at this age.

One might say that a clinic that had success with more of these difficult couples was the one to choose, rather than the one that got any old Tom, Harry or Belinda with child.

There is no information about patient lifestyle and in particular smoking history. No doubt it is collected, but it is not shown in the HFEA guide. Knowing whether one or both partners smoke is important. Not only has it been known for some time that smoking can affect a woman's fertility and IVF success, but Canadian research has now suggested that exposure to smoke from a smouldering cigarette is just as damaging.

In work from Warren Foster and colleagues at McMaster University in Hamilton Ontario, published today in Europe's leading reproductive medicine journal, Human Reproduction, a striking difference was found in implantation and pregnancy rates in 225 women, divided into non-smokers undergoing IVF, smokers and "side stream" smokers - women who lived with a partner who regularly smoked (the mean number of cigarettes smoked was 10.8).

The data was startling. Embryo quality and fertilisation rates appeared the same in the three groups, but pregnancy rates per embryo transfer were 48% in non-smokers and about 20% for both smokers and side stream smokers. Non-smokers achieved an implantation rate of 25%, whereas in both those groups exposed to smoke it was 12%.

Nevertheless the 80,000 trying to access the website clearly believe the HFEA data to be critical. Up to a point, Lord Copper. Collection of metrics is essential, especially in this area of medicine, much of which is outside the NHS. Without metrics it is impossible to make comparisons and the authority owes it to patients to use these to root out clinics whose work is sub-standard. Couples need to be discerning and use data to equip them in conversations with clinics. Figures do not say it all but provide a solid foundation of reassurance. You need to like and trust those who will be looking after you. Above all, you need to be sure that this is what you want because what league tables do not reflect is the misery of those that try and fail.