Computer Diagnosis : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 3)

Possible Criteria

Strobos suggested several criteria for determining whether software has the potential to adversely affect human health. Among them:

Is the software intended for critical use, such as pointing out imminent danger in an intensive care unit, or for a less crucial purpose, such as to store diagnostic images such as CT scans?

Is the user aware of the limitations of the program, and whether any of its recommendations depart from conventional medical practice?

How specific is the software to a particular patient? Does it provide general information on a condition, or does it manipulate specific data from a specific patient to develop a specific treatment plan?

How quickly do the software's recommendations need to be implemented? For instance, with an electrocardiogram program, will it recommend defibrillation at the appropriate time, or will it merely point out that a particular rhythm should be checked for abnormalities?

And, as Strobos pointed out, software is constantly being upgraded and improved, and customized. Such revisions need to be checked for their impact on the safety and effectiveness of the device.

"The [evaluation] process should not end when the software leaves the laboratory," Strobos said. "Postmarketing controls, as part of a life-cycle approach to software design, are important and should not be overlooked in developing a new system of agency review."

Rapid Recent Developments

Diagnostic programs have been around since the 1950s. The early programs were not used widely because they were unreliable, ran on bulky mainframes, and required a doctor to double as a data processing clerk. But in the last decade, engineers have put together more accurate and convenient programs. Hardware has shrunk to the size of a desktop, while computer memory has vastly expanded. Modems or network cables can easily link them together.

In most stand-alone diagnostic systems the physician enters the symptoms, test results, and medical history into the program, which then suggests a list of possible diagnoses. Some even provide a probability — in a person with severe, recurring headaches, for instance, the computer might say there is a 97 percent probability that the patient has sinusitis, but only a 6 percent probability of a brain tumor.

The programs can also help by highlighting some of the more likely diagnoses.

"If I see someone with a given set of symptoms, I can usually think of 20 or 30 things that it could be, off the top of my head," Voytovich said. A decision support system "helps me to narrow it down to a few possible diagnoses."

So far, the results of the programs have been mixed. A study by Eta S. Berner, Ph.D., of the University of Alabama, and colleagues from around the country, published in the New England Journal of Medicine, rated four of the most popular computer programs for medical diagnosis. The ratings were based on their ability to diagnose 105 cases chosen by a panel of experts, including some so complex they would not often be seen by the average physician.

The study found the programs correctly diagnosed the conditions between 50 and 75 percent of the time, depending on the complexity of the case, particularly whether more than a single disease was present.

Berner, a specialist in medical education, said that evaluation of the programs must also consider the doctor's rate of accuracy.

"If the physician is making an accurate diagnosis only 30 percent of the time, these programs would be better than a doctor," Berner said. "The consumer expects the doctor to be right 90 percent of the time, and that these programs will help."

Increased Complexity

As the knowledge base expands, the systems become more complex, requiring ever larger amounts of memory. To help overcome that problem, PKC Corp. in Vermont, has begun marketing "Problem Knowledge Couplers," diagnostic software sold in modules that target a specific area. Under current FDA policy the software is not regulated.

The PKC system prompts the physician with on-screen questions until it roots out the possible causes of the symptoms, then directs the physician to couplers, or software packages, that cover the appropriate disciplines.

So far, PKC has developed 50 couplers, covering areas as diverse as hypertension, lung cancer, obesity, and male erectile problems.

A "triage" coupler is used to help physicians determine whether a patient who calls with a problem needs to go to the emergency room, at an average cost of $230, or just make an appointment to come to the office.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.