A blood clot in the leg or lung, or venous thrombosis, is nothing to fool around with. In fact, most blood clots are potentially fatal. Therefore, physicians whose patients might have clots may overtest for them, in order to be absolutely certain before they rule clots out. Obviously, we want our doctors to be this conscientious. But overtesting can be inconvenient for the patient and invasive, in the case of lung clots and it's expensive as well. Therefore, Dr. Philip Wells is working to develop ways to safely reduce unnecessary testing.

In one project, Dr. Wells has developed prediction rules to facilitate the process of diagnosis. These rules can help identify both correct and incorrect results from some diagnostic tests. For example, when ultrasound is used to produce an image of the veins of the leg, a false positive can result in other words, the test may sometimes yield an image of a clot that is not actually there. In this case, if the prediction rules indicate that this particular patient is unlikely to have a clot, the ultrasound's positive result may be false. Similarly, if the ultrasound is negative, but the prediction rules indicate a high probability of a clot, the ultrasound's negative result may be false as well. In either situation, when the prediction rules contradict the diagnostic results, the physician will undertake further diagnostic tests.

Dr. Wells has proven that his prediction rules work, and is now trying to improve their use by combining them with another diagnostic test for venous thrombosis. This second test is based on the fact that the body releases a product known as D-dimer into the bloodstream when a clot forms. Therefore, a patient with no D-dimer in his or her blood probably does not have a clot. Dr. Wells and his team hope that by combining the prediction rules with the D-dimer test, they can reduce the need for ultrasound, which is more cumbersome, more expensive, and more time-consuming to use. In a trial currently under way, Dr. Wells and his team are testing a practice of not sending patients for ultrasound when the prediction rules suggest clots are unlikely and the D-dimer test is negative.

Using a separate set of tests, Dr. Wells and his team are investigating a similar strategy for patients with pulmonary embolism. In both cases, the prediction rules incorporate known risk factors for clotting, specific symptoms and signs that could be caused by a clot, and whether or not there's a likely alternative cause for the symptoms. These ventures also aim to help emergency departments decide what to do at night, when they don't have access to ultrasound.

Some of Dr. Wells's other projects are designed to evaluate the treatments that are prescribed to patients, once a diagnosis has been made. One substance under investigation is a relatively new product, a low-molecular weight heparin, which is now making it possible to treat patients for clots at home. A number of similar products are available, and are also in use for other disorders, such as unstable angina and stroke. However, no one has compared these products to each other. Dr. Wells and his team have therefore set out to determine whether they differ from each other in their safety and effectiveness as a treatment for venous thrombosis. Any differences that may be found may also apply to the other, more common disorders for which these pharmaceuticals are prescribed. About 1,000 patients will be enrolled in this random trial, and followed for about three months to determine which group has a higher rate of complications such as bleeding.

Dr. Wells is also collaborating with a number of other centers on several other studies. One of these will determine the optimal duration of treatment with oral anticoagulants like warfarin or low-molecular weight products. In this randomized trial, treatment over a period of two years is being compared with a three-month treatment period. Another trial involves pregnant women who have had a previous blood clot. Interestingly, it is not known whether or not women in this situation are at risk for a new clot. Dr. Wells and his collaborators have designed a cohort study to confirm or refute the impression given by existing literature that these women are not at risk. In a third project, the use of low-molecular weight heparin is being evaluated in two separate dosage amounts and compared with aspirin to determine whether it might provide better outcomes for stroke victims, as far as continuing disability is concerned.

Dr. Wells has also begun constructing an internet site designed to help community physicians with decision analysis through the incorporation of clinical models and treatment algorithms developed at the Loeb. This site will be an efficient and effective way to disseminate Loeb research and put it into practice.

In yet another project, Dr. Wells is working with a radiologist Dr. Steve Millward at the Civic Hospital to evaluate a new type of inferior vena cava filter. This is a cone-shaped device that is inserted into a patient's vena cava (the primary blood vessel that returns blood to the heart) if he or she is are at risk of having a blood clot travel to the lungs, but for some reason like a tendency toward bleeding cannot take blood thinners. In the past, the only such filter was permanent. In a limited test, Drs. Wells and Millward will investigate the safety and effectiveness of this new filter, which can be removed in ten days.

Cost-reductions are only one element among the many investigated by Dr. Wells, whose focus is on patient safety, comfort, and outcome. But when improving patient care simultaneously reduces costs, everyone benefits. It is through work like his that more medical win-wins will be achieved, combining lower pricetags with superior patient care.