Definition of the post-thrombotic syndrome, differences between existing classifications.
BACKGROUND
Accepted diagnostic criteria exist for the diagnosis of deep vein thrombosis (DVT). However, no uniform definition for the diagnosis and treatment of the post-thrombotic syndrome (PTS) exists. We examined the various definitions of PTS that are used and their relationships with invasive venous pressure measurement.


METHODS
Patients who had previously suffered a documented DVT underwent clinical evaluation of both lower limbs in which we used five clinical definitions to grade PTS. We included the definition of Widmer, the CEAP classification, the venous clinical severity score (also without compression therapy), and the definitions according to Prandoni and Brandjes in the evaluation. We compared all the clinical scoring systems with invasive ambulatory venous pressure measurement.


RESULTS
In total 124 patients were enrolled in whom both legs were evaluated. Thirteen patients had previously suffered bilateral DVT and nine patients had had an ipsilateral recurrent DVT. In the limbs with DVT, 10 (7%) to 29 (21%) were defined as severe PTS, compared to 0-4 (4%) in the control legs. Mild-to-moderate PTS in the DVT legs ranged from 23 to 49%, compared to 13-34% in the control legs. Overall the presence of any PTS in the DVT legs varied from 30% (VCS without compression) to 66% (Brandjes). The scoring systems of Brandjes and VCS showed a tendency towards more legs to be defined as severe PTS. Absolute frequencies of PTS in DVT legs were highest for the classifications according to Widmer, Prandoni and Brandjes. Differences in proportions of any PTS calculated between DVT and control legs varied from 18 to 39%, while odds ratios varied between 2.2 and 5.2 for the different definitions. The CEAP classification and definition of Brandjes show a moderate relation to Widmer, kappa=0.53 and 0.52, respectively. The VCS shows in all comparisons a poor correlation (kappa 0.22-0.41). Prandoni has a moderate correlation with most definitions (kappa 0.40-0.44).


CONCLUSIONS
All clinical definitions of PTS were highly associated with the reference standard of ambulatory venous pressure, with higher AVPs observed in the more severely affected groups. The ability of the scoring systems to discriminate between DVT and control legs as well as the observed prevalence of PTS differed substantially. In part this is due to the considerable overlap in AVP in the different clinical groups, reflecting the fact that our reference standard has substantial deficiencies. No clear advantage was found in any one system of classification over the rest.
Kolbach
D N
DN
Department of Epidemiology, University Maastricht, Maastricht, The Netherlands. dinanda.kolbach@epid.unimaas.nl
Neumann
H A M
HA
Prins
M H
MH
D001458:Bandages; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D011186:Postphlebitic Syndrome / Q000145:classification* / Q000175:diagnosis* / Q000628:therapy; D012720:Severity of Illness Index; D014690:Venous Pressure; D020246:Venous Thrombosis / Q000175:diagnosis / Q000628:therapy