[Evaluation of an internal guideline for the diagnostics of deep vein thrombosis]

In line with the application of evidence-based medicine as part of the day-to-day clinical practice of a community hospital internal guidelines concerning relevant diagnostic or therapeutic problems were developed. The authors retrospectively compared all data of patients with the tentative diagnosis of deep vein thrombosis (DVT), who underwent further diagnostics before and after implementation of an internally developed guideline for the diagnostics of DVT. The aim was to evaluate if the internal guideline was applied by the doctors in the daily routine and if the implementation led to a change and rationalization of the diagnostic process, in particular with regard to reducing invasive examinations.

In a retrospective controlled cohort study the medical records of in- and outpatients (n = 371) receiving further diagnostics following a tentative diagnosis of DVT were screened. The kind of examinations, the duration of the diagnostic process and the rate of hospitalization for DVT were compared between the intervention group (n = 185), treated in the initial 10 months following guideline implementation, and the control group (n = 186), treated in the 10 months prior to implementation. Furthermore, the physicians' compliance with the internal guideline was assessed.

After implementation in 114 of 185 cases (62%) the treating doctors based their diagnostic procedure on the internal guideline. There was a significant decrease of phlebographies (45.4% vs. 74.2%; RR 0.61 [95% CI 0.51; 0.73]). By contrast, the number of D-dimer tests (81.6% vs. 33.3%; RR 2.45 [95% CI 1.98; 3.03]) and of duplex sonographies (42.2% vs. 21.5%; RR 1.96 [95% CI 1.42; 2.71]) increased significantly. A reduction of the hospitalization rate for further diagnostics of primary ambulant patients (51.3% vs. 60.4% of the tentative cases; RR 0.85 [95% CI 0.69; 1,04]) without a significant change in the final number of DVT diagnoses (33.3% vs. 27.6%; RR 0,83 [95% CI 0,61; 1,13]) was found. There was a slight increment in the mean length of diagnostic process (2.12 vs. 1.84 days).

The implementation of an internal guideline for the diagnostics of DVT led to a significant reduction of the hospitalization rate and to a considerable change of the diagnostic procedure in favor of noninvasive diagnostic tests, for patients presenting with a diagnosis of suspected DVT.