The Tricorder X-Prize is a $10M competition to foster innovation in medical diagnostics. The goal of the competition is to create a medical device that can diagnose 15 diseases. The competition guidelines do not state which 15 diseases the tricoder will need to diagnose, however, it seems the competition guidelines will be refined in September. Maybe they will be announced at that point. Maybe they won’t be announced before the competition. For now, it’s fun to speculate which disease should be included.
In 2008, the Center for Disease Control and Prevention did a survey of ambulatory care in the US. They summarized the most prevalent diagnoses at office visits for nearly a million participants. The most common of all diagnoses was essential hypertension.The fourth most common diagnosis was diabetes mellitus. Each of these medical conditions has a fairly well-understood decision tree for diagnosis.
|Primary Diagnosis||Number of Visits||Percentage|
|Routine infant or child health check||43,178||4.52%|
|Acute upper respiratory infections, excluding pharyngitis||29,296||3.06%|
|Arthropathies and related disorders||28,404||2.97%|
|General medical examination||20,913||2.19%|
|Rheumatism, excluding back||18,757||1.96%|
|Specific procedures and aftercare||18,372||1.92%|
|Follow up examination||17,652||1.85%|
|Heart disease, excluding ischemic||17,017||1.78%|
|Otitis media and eustachian tube disorders||15,812||1.65%|
|Disorders of lipoid metabolism||15,274||1.60%|
|Ischemic heart disease||14,448||1.51%|
|All other diagnoses||528,885||55.32%|
Table 1: Primary Diagnosis Groups from NAMCS 2008 Survey 
My understanding — and I am not a doctor — is that hypertension is diagnosed primarily with a high blood pressure reading. You do have to make sure that the reading is repeatable and not primarily influenced by external factors, such as the presence of a doctor. Overall, it sounds like diagnosing hypertension boils down to getting consistently high blood pressure readings for the patient’s profile (gender, age, etc…). Blood pressure is not difficult too measure non-invasively — you see blood pressure monitoring machines in grocery stores. The main design consideration for the Tricorder competition would be is there an even less non-invasive way to do it? One that does not involve requiring the patient to strap a band around themselves. Even using a traditional approach, for the price of a blood pressure monitor, a device could diagnose nearly 5% of all office visits in the US.
Diabetes mellitus is #5 with 2.7% of office visit diagnoses. Again, my understanding is that the decision tree is pretty simple: blood glucose readings outside of the norm for a patients profile. However, blood glucose is traditionally measured very invasively, by taking a small blood sample. While the Tricorder X-Prize guidelines do not rule out devices that use invasive techniques, they strongly encourage noninvasive techniques. In fact, a medical doctor on our board at Chesney Research, described noninvasive blood glucose monitoring to me as one of the “holy grails” of medical device technology. Since one of the stated goals of the competition is to drive sensor technology, I think diagnosing diabetes has to be one of the diseases in the competition.
Another holy grail is characterizing bacterial versus viral upper respiratory tract infection. This disease is the third most prevalent diagnosis in office visits, according the NAMCS survey. Right now, there’s no real way to tell the difference other than waiting; bacterial infections tend to last 7-10 days and viral only 2. However, the course of treatment is very different for each: antibiotics for the bacteria, but not for the virus, since they do not respond to antibodies.
Further down the list is heart disease, the non-ischemic variety, that is, not due to low blood volume. Heart disease is a pretty broad category. However, there are analog integrated circuits on the market aimed at measuring electrocardiogram (ECG) signals. For the price of this chip (typically around $20) and the appropriate interface with the patient, a medical device could take a big step towards diagnosing heart disease. There is also a wealth of information on the links between heart disease and hypertension and heart disease and diabetes. With an ECG, a blood pressure monitor, a glucose meter and some fancy AI, a team may be well on its way to gobbling up a significant portion of heart diseases diagnoses. In fact, those three, hypertension, diabetes and heart disease, would get you nearly one out of every ten (9.24%) of all office visit diagnoses.
If we look at the NACMS top 20 again, and take out routine follow-ups, checkups and pregnancy, we are left with 14 diseases. They are given in Table 2. They accounted for nearly one third of all office visits in 2008.
|Rank||Primary Diagnosis||Number of Visits||Percentage|
|3||Acute upper respiratory infections, excluding pharyngitis||29,296||3.06%|
|4||Arthropathies and related disorders||28,404||2.97%|
|10||Rheumatism, excluding back||18,757||1.96%|
|13||Heart disease, excluding ischemic||17,017||1.78%|
|15||Otitis media and eustachian tube disorders||15,812||1.65%|
|16||Disorders of lipoid metabolism||15,274||1.60%|
|17||Ischemic heart disease||14,448||1.51%|
Table 2: Top 14 Diseases, Including Chronic Conditions from NAMCS 2008 Survey Data
The competition’s 15 diseases will need to be diagnosed on 30 different patients and the Tricoder will be evaluated for its effectiveness and ease of use by a panel of judges. The devices should be able to tell the patient if they need to go see a doctor or not. These 14 diseases are a good place to start.
 National Ambulatory Medical Care Survey: 2008 Summary Tables. The Center for Disease Control and Prevention. http://www.cdc.gov/nchs/ahcd.htm