The Long and Short of It
Posted by Steve Rauch at 4:12 PM
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Whenever I participate in the New Hire Clinical Orientation, I bring a recent news item on medical research. In preparation for the orientation on December 2, I checked my usual online sources. A story on the NHS Behind the News site caught my eye.
Finger Length Predicts Prostate Cancer. This web site evaluates recent medical research that has attracted media attention. They do a first-rate job summarizing the research, stating what conclusions are possible from the type of research done, and give their own appraisal of the study and often comment on the media headlines and clamor.
This research compared the ratio of the length of a man's index finger to ring finger and compared that to the incidence of prostate cancer to see if this ratio would work as a low-cost marker for prostate cancer. In the study, over half of the men had a shorter index finger than ring finger. Statistically, more men whose index finger is shorter than their ring finger had prostate cancer. This length ratio is linked to the testosterone exposure as the fetus develops in utero.This exposure to the hormone is thought to influence the later likelihood of developing prostate cancer.
The synopses on Behind the News are done by Bazian (their name is a delightful play on "Bayesian" analysis). They have written a case study of their NHS work. I rather expected them to take the finger length study to task. Really, finger length being predictive of cancer?
Instead, they were much more accepting of key parts of the analysis. They accepted the type of study, liked the size of the study. But they had questions about some other aspects of the research. While the percentage of men with indexed fingers shorter than ring fingers in this study is over 50%, fewer than half the men had prostate cancer. Bazian suggests that there is some other cause at work here that likely affects finger length as well as a propensity to develop prostate cancer. They even mention that this study looked only at men's right hands, but some studies looking at both hands don't find a straightforward relationship between finger length and hormone exposure.
Whenever a medical research items makes a big splash, head on over to Behind the Headlines to see what Bazian has to say about it. Besides, it is a fun way to learn about the different study types and improve your evidence-based practice appraisal skills.