Skip Navigation U.S. Department of Health and Human Services
Agency for Healthcare Research Quality
Archive print banner

Clinical Decisionmaking

This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: Let us know the nature of the problem, the Web address of what you want, and your contact information.

Please go to for current information.

Studies offer guidance to help physical therapists identify and refer patients at risk of deep vein thrombosis

Physical therapists often see patients who have just suffered a major trauma or had major orthopedic surgery such as knee or hip replacement. These patients are at high risk of developing deep vein thrombosis (DVT, blood clot in the deep vein of the leg) after hospital discharge. Because DVT, particularly proximal DVT (PDVT, affecting the popliteal and thigh veins) is a potentially life-threatening disorder (the clot can travel to the lung and cause pulmonary embolism), physical therapists should be highly skilled at identifying outpatients who are at risk for the condition.

A recent study suggests how physical therapists can identify high-risk patients who should be immediately referred to a physician. A second study shows that the majority of physical therapists underestimate the probability of DVT in their patients. Both studies, which are summarized here, were supported by the Agency for Healthcare Research and Quality (HS13059) and led by Daniel L. Riddle, P.T., Ph.D., F.A.P.T.A., of Virginia Commonwealth University.

Riddle, D.L., and Wells, P.S. (2004, August). "Diagnosis of lower-extremity deep vein thrombosis in outpatients." Physical Therapy 84(8), pp. 729-735.

Because most physical therapists cannot prescribe formal diagnostic tests for PDVT, such as compression ultrasound, they need a method for determining when a patient with symptoms suggestive of PDVT (lower-extremity pain and swelling or calf tenderness) should be referred to a physician for a diagnostic workup. Researchers recently compiled a clinical decision rule (CDR) to diagnose PDVT from risk factors, signs, and symptoms. They assigned a numerical score to nine factors based on clinical examination or medical history to develop the CDR. These factors ranged from active cancer, paralysis, recently bedridden, lower-extremity swelling, and calf swelling over 3 cm (all given a score of one) to alternative diagnosis as likely or greater than that of PDVT (given a score of -2).

Patients who had a score of 0 or less had a probability of PDVT of 3 percent, those with a score of 1 or 2 had a 17 percent probability, and those with a score of 3 or higher had a 75 percent probability of PDVT. By using the CDR, physical therapists can judge the urgency of referring the patient to a physician. For example, if a patient is found to have a high probability of PDVT (a score of 3 or higher on the CDR), the physical therapist should call the referring physician immediately and encourage a diagnostic workup that day to reduce the risk of pulmonary embolism.

Riddle, D.L., Hillner, B.E., Wells, P.S., and others (2004, August). "Diagnosis of lower-extremity deep vein thrombosis in outpatients with musculoskeletal disorders: A national survey study of physical therapists." Physical Therapy 84(8), pp. 717-728.

In this national survey of physical therapists, the majority of those surveyed underestimated the probability of PDVT in two vignettes (87 and 64 percent, respectively) of outpatients with musculoskeletal disorders who had a high probability of PDVT. The survey results also suggest that about 25 percent of physical therapists would likely not contact the referring physician when seeing a patient with a high probability of PDVT. The survey, which presented six vignettes, was sent to a nationally representative random sample of 1,500 physical therapists (969 completed the survey). The clinical decision rule served as the gold standard for PDVT probability.

In four of six vignettes, a majority of therapists either overestimated or underestimated PDVT probability. Perhaps more troubling was the proportion of therapists (15 to 90 percent depending on the vignette) who reported that they would not have contacted the referring physician about the patient's condition. For the two high-probability cases, 32 percent and 27 percent of the physical therapists reported that they would not have contacted the referring physician. For the two moderate-probability cases, 15 percent and 30 percent of the physical therapists would not have contacted the referring physician.

Physical therapists generally did not agree on which patients were at risk. Overall, 24 percent of them agreed on the two low-probability cases, 16 percent on the two moderate-probability cases, and only 6 percent on the two high-probability cases. Therapist experience, certification status, place of practice, and region of the country did not explain the findings. The researchers conclude that the care of physical therapy outpatients could be improved by use of the clinical decision rule employed in this study to diagnose risk of PDVT in outpatients.

Return to Contents
Proceed to Next Article

The information on this page is archived and provided for reference purposes only.


AHRQ Advancing Excellence in Health Care