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History of Medicine |

The Nomogram Epidemic: Resurgence of a Medical Relic

David A. Grimes, MD
[+] Article and Author Information

From Family Health International, Research Triangle Park, North Carolina.


Disclaimer: The views expressed in this article do not necessarily reflect those of Family Health International or the U.S. Agency for International Development.

Grant Support: By Family Health International, with funds from the U.S. Agency for International Development.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: David A. Grimes, MD, Family Health International, PO Box 13950, Research Triangle Park, NC 27709; e-mail, dgrimes@fhi.org.


Ann Intern Med. 2008;149(4):273-275. doi:10.7326/0003-4819-149-4-200808190-00010
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The obsolete calculators known as nomograms have become epidemic in recent medical literature. The frequency of articles in PubMed retrieved with this search term nearly doubled between 1990 to 1999 and 2000 to 2007. Popular in medicine from about 1925 to 1975, a nomogram is a crude graphical means for solving an equation by placing a straightedge across several scales. Today, most reported nomograms are inconsistent with both established definitions and half a century of clinical use. The need for nomograms disappeared with the advent of personal computing. Instead of constructing nomograms, authors should develop software, such as prediction models, that can either be downloaded to personal digital assistants or be used on the Internet. Modern computing features both accuracy and speed; nomograms offer only the latter.

Figures

Grahic Jump Location
Figure.
Nomogram for posttest probability.

Adapted from reference 4, with permission of the Massachusetts Medical Association.

Grahic Jump Location

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Comments

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Nomograms may be relics, but where is the evidence?
Posted on August 21, 2008
Samuel H Zwillich
No Affiliation
Conflict of Interest: None Declared
Dr. Grimes's review of the history of nomograms was informative. However, his criticism of the "epidemic" of nomogram resurgence was fundamentally unsubstantiated. Grimes states that "...nomograms provided speed in calculation at the cost of precision", without providing any evidence that the lost precision mattered. Where is the evidence, for example, that calculating likelihood ratios to additional decimal places improves clinical decision making? Conversely, where is the evidence that calculating medication doses using a body surface area nomogram adversely impacted patient well-being?

An alternative, testable hypothesis is that contemporary reliance on computer-generated numbers numbs physicians to the meaning of their calculations and blinds them to errors that would have been obvious on a nomogram. Personal computing may be more convenient than nomograms, but inconvenience does not equal inappropriateness ("Hence, the resurgence of this relic is inappropriate").

Conflict of Interest:

None declared

Nostalgia
Posted on September 22, 2008
David A. Grimes
Family Health International
Conflict of Interest: None Declared

Re: Dr. Zwillich complains that my criticism of the "nomogram" epidemic was "fundamentally unsubstantiated." Moreover, he suggests that use of computers "numbs" physicians. I infer that he would prefer to return to the days of slide rules for physics problems and pencil-and-paper arithmetic for completing income tax returns. When slide rules were used, mistakes by a factor of 10 were easy to make, since the placement of the decimal could be unclear. This does not happen with a calculator. While the utility of electronic vs. hand calculations may be a testable hypothesis, some benefits of technology are self-evident(1).

Despite Dr. Zwillich's apparent nostalgia, I do not miss the "good old days" of hand calculations. Judging from the ubiquitous use of computers and calculators in everyday life, I am not alone.

References

1. Smith GC, Pell JP. Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials. BMJ 2003;327:1459-61.

Conflict of Interest:

None declared

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