Refining Risk for Deep Vein Thrombosis in Hospitalized Patients

Excerpt

Clinicians often assume that the test characteristics for a diagnostic test are fixed. This allows clinicians to smoothly transition from a pre-test to a post-test probability when considering diagnostic or treatment thresholds. Unfortunately, these “fixed” test characteristics apply best to the derivation group studied and may not always be generalizable to other populations. Applying a diagnostic test outside a derivation population may lead to “spectrum bias,” or the false assumption that a diagnostic test will work well in any population studied.1 An often-taught example of spectrum bias is the use of the outpatient-derived Wells score for the detection of deep venous thrombosis (DVT) in the inpatient setting. Compared to outpatients, hospitalized patients have a higher prevalence of pro-thrombotic characteristics such as immobility, comorbid illness and recent surgery, which makes the Wells score test characteristics less reliable in the inpatient setting. …