Tuesday, November 06, 2007

Now your doctor can check your white blood cell count at his office in just 3 minutes!!!

Today, Medscape reported that the FDA has granted three new 510(k) clearances. This means that the companies involved will be allowed to market and sell their respective technologies. One of them, a gadget for surgically stabilizing the cervical spine (the neck), I'll defer to my orthopedic and neurosurgical colleagues to comment on.

The other two are worthy of comments by an internist.

The first one is a point-of-care (POC) assay of a patient's white blood cell count (WBC). This means that this test, which is normally done in a fancy lab will be possible at the doctor's office and the results will be available within three minutes.

WBC's are useful in a variety of clinical settings but I really question whether they need to be available as a POC study. When WBC's are high or low, that usually means infection of some sort or perhaps a malignancy. It's a very nonspecific test because so many things (including some non-disease states) can cause changes.

It is very rare however, that a doctor will need to know a patient's WBC immediately in his office to render a clinical decision. Truthfully, it'll take a doctor more imaginative than me to think of such a situation. If a patient is really sick, I'm going to admit him to the hospital; I don't need a WBC to tell me that. Some of us actually make clinical decisions based on talking to the patient and even examining them if you can believe it!

Don't get me wrong, WBC's are important. I order them all the time from clinic. I just don't need to know the results immediately. A day or two won't make a difference. On the other hand, if I have a sick patient in the emergency room, a "stat" WBC is often essential but hospital labs already are set up to do these quickly. In fact these results are far more useful because then, the WBC is part of a complete blood count which gives me more complete information. But in the E.R., I'm not ordering it to tell me that the patient is sick. I'm getting it because I need to know which diagnostic pathway to travel down next and I need to move fast.

Now there are some useful POC tests. I like getting blood sugar tests right then and there. They help me make immediate decisions on how to modify someone's diabetic care. The same is true with HemoCues (a POC test for anemia). This is sometimes helpful in managing certain problems such as iron deficiency because it allows me to know if therapy is adequate and if I need to modify treatment. There are other examples.

Unfortunately, I don't think WBC's fall into that category. I seriously doubt that most primary care providers (PCP's) will pick up on this subtlety. A lot of them will probably purchase this technology, a lot of them will make money running the test, and a lot more useless WBC's will be performed. Guess what? This will become one more factor in rising healthcare costs and with very little to show for it.

Also, more useless WBC's being ordered means a higher percentage of falsely abnormal test results. This inevitably leads to more clinical testing, more diagnostic dead-ends, more needless patient anxiety, and more wasted healthcare dollars.

Who knows, maybe I'm wrong. Maybe insurance companies will balk at paying for it and when patients are told they'll have to pay out-of-pocket, they'll ask the hard questions that should be asked of all forms of medical technology: "How much does it cost and what will this really do for me?"

I can dream can't I?

I'll try to blog about the third technology approved by the FDA another time (a POC blood test for the virus that causes genital herpes).

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Anonymous Anonymous said...


I have to disagree with you on this one. A case I had today comes to mind.

The patient presented with abdominal pain. Knowing at the time I saw her that her WBC was only 13.8, I would have elected to treat her diverticulitis on an outpatient basis. We admitted her, and she'll get 24 hours of IV antibiotics, when most likely she could (based on the not very elevated WBC and lack of any serious fever) have been treated outpatient with bowel rest, oral antibiotics, and close follow up.

We do POC testing for glucose, strep, mono, and pregnancy. We only run POC tests when they will directly affect our management of the patient.

Having this test available would have saved the healthcare system about $3000. We don't do nearly enough CBC's (as again, we only use them when they will affect our management of the patient) to warrant having the equipment to do this in house. This "useless" test would have come in VERY handy today.


Vincent Meyer, MD

November 10, 2007 7:57 PM  
Blogger The Medicine Man said...

Dear Vincent,

I won't second guess your decision in this case. However, as a general rule, I make the decision to treat diverticulitis in or out of the hospital on strictly clinical grounds.

If I thought the patient didn't look too sick, I wouldn't have bothered with the WBC and I'd have opted for the oral antibiotics (assuming they could take meds by mounth). On the other hand, if he looked toxic, I would admit regardless of the WBC.

Either way, the WBC wouldn't have helped me with that decision.

Again, this is my general approach to diverticulitis, not necessarily the correct one.


November 11, 2007 1:23 PM  

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