Incidence studies that relied solely on clinical diagnosis of DVT will not be reviewed here. Thus, clinical diagnosis may both overestimate and underestimate the true incidence. 1 Conversely, since symptoms can be vague or even absent, DVT may be underdiagnosed, especially among outpatients. This was problematic because less than half of patients suspected of having DVT had the diagnosis confirmed when objective tests were performed. Older community-based studies relied on clinical symptoms and signs to diagnose DVT, without objective testing. It is uncertain how many of these subclinical DVTs would have become symptomatic and reached medical attention.
Most incidence studies have been conducted in hospitalized patients, which overestimates the general incidence for 2 main reasons: hospitalized patients are at higher risk for DVT (which will be illustrated) and, in many of these studies, screening tests were used to diagnose DVT in the absence of symptoms suggestive of DVT. Also, autopsy rates in general are low and overrepresent unusual cases. Autopsy studies have been of little use, since DVT in itself is not often fatal.
The true incidence of DVT in the population is difficult to assess. First, however, it is instructive to review the epidemiological data on DVT incidence and risk factors, because estimation of the probability of DVT is influenced by its incidence in the population from which the patient derives, which in turn is influenced by the prevalence of underlying risk factors for DVT in the same population. The aim of this article is to review the accuracy of clinical examination and of clinical prediction indexes for DVT diagnosis in symptomatic patients with suspected DVT. This, in turn, could help to direct the choice and interpretation of diagnostic tests and subsequent decision making regarding treatment, and could promote the rational and cost-effective use of these tests. Accurate clinical prediction indexes for DVT diagnosis could improve estimation of the pretest probability of DVT in the individual patient with leg symptoms. Their use may improve the efficiency and accuracy of physicans' judgments. 4, 5 Clinical prediction indexes are usually derived from multivariate mathematical models, which are then simplified for use by clinicians in individual patients. There has been interest recently in the use of clinical prediction indexes to help physicians improve their estimates of diagnostic or prognostic outcomes. 1 - 3 Hence, 60% to 80% of referred patients do not have DVT but are nonetheless subjected to diagnostic testing. 1 Studies during the last 30 years have shown that among symptomatic patients with suspected DVT referred by clinicians for diagnostic testing, the diagnosis is usually confirmed in only 20% to 40% of patients, a figure that has not changed with time. With the advent of contrast venography as a means of objectively diagnosing DVT, it became evident that symptoms and clinical signs were extremely inaccurate for the diagnosis of DVT. Symptoms and clinical signs suggestive of deep venous thrombosis (DVT) are common in the general population and have numerous possible causes. Further study is needed to determine whether clinical prediction indexes have a role in improving the diagnostic process in patients with suspected DVT. Symptoms and clinical signs, when combined with other patient information such as the presence or absence of known risk factors for DVT, can improve clinical prediction considerably.
Epidemiological data on DVT incidence and risk factors were reviewed, as were published data on the accuracy of clinical diagnosis of DVT, with the use of both symptoms and signs in isolation and symptoms and signs combined with other clinical information in the form of clinical prediction indexes. However, clinicians have other information at hand, such as data on risk factors for DVT, that may help improve their ability to predict a diagnosis of DVT in the individual patient. Studies have shown that symptoms and clinical signs in themselves are inaccurate for the diagnosis of DVT. Symptoms and clinical signs suggestive of deep venous thrombosis (DVT) are common and have numerous possible causes. Shared Decision Making and Communication.Scientific Discovery and the Future of Medicine.Health Care Economics, Insurance, Payment.Clinical Implications of Basic Neuroscience.Challenges in Clinical Electrocardiography.
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