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The story of the Cochrane logo

The Cochrane Collaboration logo illustrates both our organisation’s global objectives and key scientific processes. The circle framed by the 'C' of Cochrane and the mirror image 'C' of Collaboration reflects the international collaboration that makes our work relevant globally. The inner part of the logo illustrates a systematic review of data from seven randomised controlled trials (RCTs), comparing one healthcare treatment with a placebo. Each horizontal line represents the results of one trial (the shorter the line, the more certain the result); and the diamond represents their combined results. The vertical line indicates the position around which the horizontal lines would cluster if the two treatments compared in the trials had similar effects; if a horizontal line touches the vertical line, it means that that particular trial found no clear difference between the treatments. The position of the diamond to the left of the vertical line indicates that the treatment studied is beneficial. Horizontal lines or a diamond to the right of the line would show that the treatment did more harm than good.

This diagram shows the results of a systematic review of RCTs of a short, inexpensive course of a corticosteroid given to women about to give birth too early. The first of these RCTs was reported in 1972. The diagram summarises the evidence that would have been revealed had the available RCTs been reviewed systematically. A decade later it indicates strongly that corticosteroids reduce the risk of babies dying from the complications of immaturity. By 1991, seven more trials had been reported, and the picture had become still stronger. This treatment reduces the odds of the babies of these women dying from the complications of immaturity by 30 to 50 per cent. (Observant readers may notice that the painting shown here includes eight horizontal lines, while the official logo includes only seven. This is because the earlier research overlooked one!)

Before a systematic review of these trials was published, most obstetricians had not realised that the treatment was so effective, and it was not very widely used. As a result, tens of thousands of premature babies probably suffered and died unnecessarily (and needed more expensive treatment than was necessary). Following the publication of this research as a Cochrane Review, the NIH released a consensus statement unequivocally recommending that “antenatal corticosteroid therapy is indicated for women at risk of premature delivery with few exceptions and will result in a substantial decrease in neonatal morbidity and mortality as well as substantial savings in health care costs.”

Data collected before and after the review’s publication showed a starting point of about 20% for corticosteroid use at the time of publication. Even before the NIH recommendation, corticosteroid use grew steadily following the review’s publication, climbing to about 65% in relevant cases by 1996. Data collected for the same 1991-1996 period showed a decrease in mortality coinciding with the increased use of corticosteroids.

Thus the Cochrane logo illustrates just one of many examples of the human costs resulting from failure to perform systematic, up-to-date reviews of RCTs of health care – and the powerful impact of evidence on guidelines, on practice, and on mortality rates.

Updated on: January 6, 2013, 10:33

Comments for improvement or correction are welcome.